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Sample records for biologically effective dose

  1. Biological effect of low dose radiation

    International Nuclear Information System (INIS)

    This document describes the recent findings in studies of low dose radiation effect with those by authors' group. The low dose radiation must be considered in assessment of radiation effects because it induces the biological influence unexpected hitherto; i.e., the bystander effect and genetic instability. The former is a non-targeted effect that non-irradiated cells undergo the influence of directly irradiated cells nearby, which involves cell death, chromosome aberration, micronucleus formation, mutation and carcinogenesis through cellular gap junction and/or by signal factors released. Authors' group has found the radical(s) possessing as long life time as >20 hr released from the targeted cells, a possible mediator of the effect; the generation of aneuploid cells as an early carcinogenetic change; and at dose level <10 Gy, activation of MAPK signal pathway leading to relaxation of chromatin structure. The genetic instability means the loss of stability where replication and conservation of genome are normally maintained, and is also a cause of the late radiation effect. The group has revealed that active oxygen molecules can affect the late effect like delayed cell death, giant cell formation and chromosome aberration, all of which lead to the instability, and is investigating the hypothesis that the telomere instability resulted from the abnormal post-exposure interaction with its nuclear membrane or between chromatin and nuclear matrix, is enhanced by structural distortion of nuclear genes. As well, shown is the possible suppression of carcinogenesis by p53. The group, to elucidate the mechanism underlying the low dose radiation effect, is conducting their studies in consideration of the sequential bases of physical, chemical and biological processes. (R.T.)

  2. Doses and biological effect of ionizing radiation

    International Nuclear Information System (INIS)

    Basic values and their symbols as well as units of physical dosimetry are given. The most important information about biological radiation effects is presented. Polish radiation protection standards are cited. (A.S.)

  3. Biological effects at low irradiation doses

    International Nuclear Information System (INIS)

    Full text: The best scientific evidence of radiation effects in humans initially came from epidemiological studies of atomic bomb survivors in Hiroshima and Nagasaki. While no evidence of genetic effects has been found, these studies showed a roughly linear relationship between the induction of cancer and extremely high dose-rate of atomic bomb radiation. This was consistent with the knowledge that ionizing radiation can damage DNA in linear proportion to high-dose exposures and so produces gene mutations known to be associated with cancer. In the absence of comparable low dose effects it was prudent to propose tentatively the no-threshold hypothesis (LNT) that extrapolates linearly from effects observed at very high doses to the same effects at very low doses. It was accepted by the International Commission on Radiological Protection (ICRP) and afterwards adopted by national radiation protection organizations to guide regulations for the protection of occupationally exposed workers and the public. This hypothesis that all radiation is harmful in linear proportion to the dose is the principle used for collective dose calculations of the number of deaths produced by any radiation, natural of generated, no matter how small (BEIR-2000). The National Council of Radiation Protection and Measurements Report 121, summarizes the basis for adherence to linearity of radiation health effects. Confidence in LNT at low doses is based on our understanding of the basic mechanisms involved. Genetic effects may result from a gene mutation or a chromosome aberration. The activation of a dominant acting oncogene is frequently associated with leukemia and lymphomas, while the loss of suppressor genes appears to be more frequently associated with solid tumors. It is conceptually possible, but with a vanishing small probability, that any of these effects could result from the passage of a single charged particle, causing damage to DNA that could be expressed as a mutation or small

  4. Biological effects of low-dose ionizing radiation exposure

    International Nuclear Information System (INIS)

    The report on the meeting of the Strahlenschutzkommission 2007 concerning biological effects of low-dose ionizing radiation exposure includes the following contributions: Adaptive response. The importance of DNA damage mechanisms for the biological efficiency of low-energy photons. Radiation effects in mammography: the relative biological radiation effects of low-energy photons. Radiation-induced cataracts. Carcinomas following prenatal radiation exposure. Intercellular apoptosis induction and low-dose irradiation: possible consequences for the oncogenesis control. Mechanistic models for the carcinogenesis with radiation-induced cell inactivation: application to all solid tumors in the Japanese atomic bomb survivors. Microarrays at low radiation doses. Mouse models for the analysis of biological effects of low-dose ionizing radiation. The bystander effect: observations, mechanisms and implications. Lung carcinoma risk of Majak workers - modeling of carcinogenesis and the bystander effect. Microbeam studies in radiation biology - an overview. Carcinogenesis models with radiation-induced genomic instability. Application to two epidemiological cohorts.

  5. SWEET CORN CULTIVAR INFLUENCES BIOLOGICALLY EFFECTIVE HERBICIDE DOSE [ABSTRACT

    Science.gov (United States)

    Competitive crop cultivars are considered a component of integrated weed management systems; however specific knowledge of interactions among crop cultivars and other management tactics, such as biologically effective herbicide dose, is limited. Observed variation in crop tolerance and weed supp...

  6. Biological effects and equivalent doses in radiotherapy: a software solution

    CERN Document Server

    Voyant, Cyril; Roustit, Rudy; Biffi, Katia; Marcovici, Celine Lantieri

    2013-01-01

    The limits of TDF (time, dose, and fractionation) and linear quadratic models have been known for a long time. Medical physicists and physicians are required to provide fast and reliable interpretations regarding the delivered doses or any future prescriptions relating to treatment changes. We therefore propose a calculation interface under the GNU license to be used for equivalent doses, biological doses, and normal tumor complication probability (Lyman model). The methodology used draws from several sources: the linear-quadratic-linear model of Astrahan, the repopulation effects of Dale, and the prediction of multi-fractionated treatments of Thames. The results are obtained from an algorithm that minimizes an ad-hoc cost function, and then compared to the equivalent dose computed using standard calculators in seven French radiotherapy centers.

  7. Effective biological dose from occupational exposure during nanoparticle synthesis

    International Nuclear Information System (INIS)

    Nanomaterial and nanotechnology safety require the characterization of occupational exposure levels for completing a risk assessment. However, equally important is the estimation of the effective internal dose via lung deposition, transport and clearance mechanisms. An integrated source-to-biological dose assessment study is presented using real monitoring data collected during nanoparticle synthesis. Experimental monitoring data of airborne exposure levels during nanoparticle synthesis of CaSO4 and BiPO4 nanoparticles in a research laboratory is coupled with a human lung transport and deposition model, which solves in an Eulerian framework the general dynamic equation for polydisperse aerosols using particle specific physical-chemical properties. Subsequently, the lung deposition model is coupled with a mathematical particle clearance model providing the effective biological dose as well as the time course of the biological dose build-up after exposure. The results for the example of BiPO4 demonstrate that even short exposures throughout the day can lead to particle doses of 1.10·E+08/(kg-bw·8h-shift), with the majority accumulating in the pulmonary region. Clearance of particles is slow and is not completed within a working shift following a 1 hour exposure. It mostly occurs via macrophage activity in the alveolar region, with small amounts transported to the interstitium and less to the lymph nodes.

  8. Effective biological dose from occupational exposure during nanoparticle synthesis

    Science.gov (United States)

    Demou, Evangelia; Tran, Lang; Housiadas, Christos

    2009-02-01

    Nanomaterial and nanotechnology safety require the characterization of occupational exposure levels for completing a risk assessment. However, equally important is the estimation of the effective internal dose via lung deposition, transport and clearance mechanisms. An integrated source-to-biological dose assessment study is presented using real monitoring data collected during nanoparticle synthesis. Experimental monitoring data of airborne exposure levels during nanoparticle synthesis of CaSO4 and BiPO4 nanoparticles in a research laboratory is coupled with a human lung transport and deposition model, which solves in an Eulerian framework the general dynamic equation for polydisperse aerosols using particle specific physical-chemical properties. Subsequently, the lung deposition model is coupled with a mathematical particle clearance model providing the effective biological dose as well as the time course of the biological dose build-up after exposure. The results for the example of BiPO4 demonstrate that even short exposures throughout the day can lead to particle doses of 1.10·E+08#/(kg-bw·8h-shift), with the majority accumulating in the pulmonary region. Clearance of particles is slow and is not completed within a working shift following a 1 hour exposure. It mostly occurs via macrophage activity in the alveolar region, with small amounts transported to the interstitium and less to the lymph nodes.

  9. Biologically effective doses of postoperative radiotherapy in the prevention of keloids. Dose-effect relationship

    International Nuclear Information System (INIS)

    Purpose: To review the recurrence rates of keloids after surgical excision followed by radiotherapy, and to answer the question whether after normalization of the dose, a dose-effect relationship could be derived. Material and Methods: A literature search was performed to identify studies dealing with the efficacy of various irradiation regimes for the prevention of keloids after surgery. Biologically effective doses (BEDs) of the various irradiation regimens were calculated using the linear-quadratic concept. A distinction between recurrence rates of keloids in the face and neck region and those in other parts of the body was made. Results: 31 reports were identified with PubMed with the search terms keloids, surgery, radiation therapy, radiotherapy. 13 reports were excluded, because no link could be found between recurrence rate and dose, or if less than ten patients per dose group. The recurrence rate for surgery only was 50-80%. For BED values >10 Gy the recurrence rate decreased as a function of BED. For BED values >30 Gy the recurrence rate was <10%. For a given dose, the recurrence rates of keloids in the sites with high stretch tension were not significantly higher than in sites without stretch tension. Conclusion: The results of this study indicate that for effectively treating keloids postoperatively, a relatively high dose must be applied in a short overall treatment time. The optimal treatment probably is an irradiation scheme resulting in a BED value of at least 30 Gy. A BED value of 30 Gy can be obtained with, for instance, a single acute dose of 13 Gy, two fractions of 8 Gy two fractions of 8 Gy or three fractions of 6 Gy, or a single dose of 27 Gy at low dose rate. The radiation treatment should be administered within 2 days after surgery. (orig.)

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

    International Nuclear Information System (INIS)

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

  11. Biological effects of low doses of ionizing radiation

    International Nuclear Information System (INIS)

    Few weeks ago, when the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) submitted to the U.N. General Assembly the UNSCEAR 1994 report, the international community had at its disposal a broad view of the biological effects of low doses of ionizing radiation. The 1994 report (272 pages) specifically addressed the epidemiological studies of radiation carcinogenesis and the adaptive responses to radiation in cells and organisms. The report was aimed to supplement the UNSCEAR 1993 report to the U.N. General Assembly- an extensive document of 928 pages-which addressed the global levels of radiation exposing the world population, as well as some issues on the effects of ionizing radiation, including: mechanisms of radiation oncogenesis due to radiation exposure, influence of the level of dose and dose rate on stochastic effects of radiation, hereditary effects of radiation effects on the developing human brain, and the late deterministic effects in children. Those two UNSCEAR reports taken together provide an impressive overview of current knowledge on the biological effects of ionizing radiation. This article summarizes the essential issues of both reports, although it cannot cover all available information. (Author)

  12. Modeling of biological doses and mechanical effects on bone transduction

    CERN Document Server

    Rieger, Romain; Jennane, Rachid; 10.1016/j.jtbi.2011.01.003

    2012-01-01

    Shear stress, hormones like parathyroid and mineral elements like calcium mediate the amplitude of stimulus signal which affects the rate of bone remodeling. The current study investigates the theoretical effects of different metabolic doses in stimulus signal level on bone. The model was built considering the osteocyte as the sensing center mediated by coupled mechanical shear stress and some biological factors. The proposed enhanced model was developed based on previously published works dealing with different aspects of bone transduction. It describes the effects of physiological doses variations of Calcium, Parathyroid Hormone, Nitric Oxide and Prostaglandin E2 on the stimulus level sensed by osteocytes in response to applied shear stress generated by interstitial fluid flow. We retained the metabolic factors (Parathyroid Hormone, Nitric Oxide, and Prostaglandin E2) as parameters of bone cell mechanosensitivity because stimulation/inhibition of induced pathways stimulates osteogenic response in vivo. We t...

  13. Biological effective doses in the intracavitary high dose rate brachytherapy of cervical cancer

    Directory of Open Access Journals (Sweden)

    Y. Sobita Devi

    2011-12-01

    Full Text Available Purpose: The aim of this study is to evaluate the decrease of biological equivalent dose and its correlation withlocal/loco-regional control of tumour in the treatment of cervical cancer when the strength of the Ir-192 high dose rate(HDR brachytherapy (BT source is reduced to single, double and triple half life in relation to original strength of10 Ci (~ 4.081 cGy x m2 x h–1. Material and methods: A retrospective study was carried out on 52 cervical cancer patients with stage II and IIItreated with fractionated HDR-BT following external beam radiation therapy (EBRT. International Commission onRadiation Units and Measurement (ICRU points were defined according to ICRU Report 38, using two orthogonal radiographimages taken by Simulator (Simulix HQ. Biologically effective dose (BED was calculated at point A for diffe -rent Ir-192 source strength and its possible correlation with local/loco-regional tumour control was discussed. Result: The increase of treatment time per fraction of dose due to the fall of dose rate especially in HDR-BT of cervicalcancer results in reduction in BED of 2.59%, 7.02% and 13.68% with single, double and triple half life reduction ofsource strength, respectively. The probabilities of disease recurrence (local/loco-regional within 26 months are expectedas 0.12, 0.12, 0.16, 0.39 and 0.80 for source strength of 4.081, 2.041, 1.020, 0.510 and 0.347 cGy x m2 x h–1, respectively.The percentages of dose increase required to maintain the same BED with respect to initial BED were estimated as1.71, 5.00, 11.00 and 15.86 for the dose rate of 24.7, 12.4, 6.2 and 4.2 Gy/hr at point A, respectively. Conclusions: This retrospective study of cervical cancer patients treated with HDR-BT at different Ir-192 sourcestrength shows reduction in disease free survival according to the increase in treatment time duration per fraction.The probable result could be associated with the decrease of biological equivalent dose to point A. Clinical

  14. Biological effects of irradiation on skin and recommended dose limits

    International Nuclear Information System (INIS)

    The range of radiation responses of the skin are reviewed in terms of the time course over which damage is expressed and the likely underlying pathogenesis. Responses of specific concern in radiological protection have been identified; these include acute necrosis/ulceration after exposure to radioactive 'hot' particles, and moist desquamation, late dermal atrophy or telangiectasia after more generalised exposures from intermediate and high energy β emitters. Acute epidermal necrosis is the only endpoint of concern after exposure to low energy β emitters. Dose-effect relationships have been established for each of these responses and on this basis recommendations for dose limitation for the skin can be made along with proposals for the depths at which dose should be assessed in routine monitoring procedures. (author)

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

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

  17. Cytogenetic effects of low ionising radiation doses and biological dosimetry

    OpenAIRE

    Gricienė, Birutė

    2010-01-01

    The intensive use of ionising radiation (IR) sources and development of IR technology is related to increased exposure and adverse health risk to workers and public. The unstable chromosome aberration analysis in the group of nuclear energy workers (N=84) has shown that doses below annual dose limit (50 mSv) can induce chromosome aberrations in human peripheral blood lymphocytes. Significantly higher frequencies of the total chromosome aberrations were determened in the study group when compa...

  18. Biologically effective uniform dose (D) for specification, report and comparison of dose response relations and treatment plans

    International Nuclear Information System (INIS)

    Developments in radiation therapy planning have improved the information about the three-dimensional dose distribution in the patient. Isodose graphs, dose volume histograms and most recently radiobiological models can be used to evaluate the dose distribution delivered to the irradiated organs and volumes of interest. The concept of a biologically effective uniform dose (D) assumes that any two dose distributions are equivalent if they cause the same probability for tumour control or normal tissue complication. In the present paper the D concept both for tumours and normal tissues is presented, making use of the fact that probabilities averaged over both dose distribution and organ radiosensitivity are more relevant to the clinical outcome than the expected number of surviving clonogens or functional subunits. D can be calculated in complex target volumes or organs at risk either from the 3D dose matrix or from the corresponding dose volume histograms of the dose plan. The value of the D concept is demonstrated by applying it to two treatment plans of a cervix cancer. Comparison is made of the D concept with the effective dose (Deff) and equivalent uniform dose (EUD) that have been suggested in the past. The value of the concept for complex targets and fractionation schedules is also pointed out. (author)

  19. Biological effects of low doses of ionising radiation

    International Nuclear Information System (INIS)

    A study was performed with the aim to examine whether the progeny of cells that had been repeatedly irradiated with low doses of gamma rays will change their sensitivity to cytotoxic agents. Four mammalian cell lines were used in the experiment. It was found that the progeny of cells irradiated in this way do not change their sensitivity to gamma rays but would change their sensitivity to various cytostatics drugs. (A.K.)

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

    International Nuclear Information System (INIS)

    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 (Co60 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)

  1. Low doses of ionizing radiation: Biological effects and regulatory control. Contributed papers

    International Nuclear Information System (INIS)

    The International Atomic Energy Agency and the World Health Organization, in cooperation with the United Nations Scientific Committee on the Effects of Atomic Radiation, organized an international conference on Low Doses of Ionizing Radiation: Biological Effects and Regulatory Control, held in seville, Spain, from 17 to 21 November 1997. This technical document contains concise papers submitted to the conference

  2. Metastatic renal cell carcinoma: can it be palliated with radiotherapy? Do higher biologically effective doses help?

    International Nuclear Information System (INIS)

    BACKGROUND: Renal cell carcinoma (RCC) has traditionally been regarded as a 'radioresistant cancer'. Yet controversy exists as to whether dose escalation can overcome the inherent resistance of such tumors when they metastasize. Using a Tumor Dose Factor (TDF) model, Onuffrey et al. (IJROB 11:2007, 1985) showed that TDF >70 was predictive of higher palliative response rates. In contrast, Halperin et al (Cancer 51:614, 1983) could not establish a correlation between TDF equivalent dose and frequency of palliative response. Since that time, the linear quadratic model has emerged as an alternative paradigm for biologically effective dose (BED). The current project was undertaken to determine the ability of radiotherapy to palliate focally metastatic RCC and to assess whether the delivery of higher biologically effective dose was more likely to bring about complete palliative response (CR). METHODS: Between 1966 and 1995, 107 patients with renal cell metastases at 150 sites were irradiated with palliative intent. Sites irradiated included bone (n=89), soft tissue (n=16), brain (n=20), spinal cord (n=9), and pulmonary (n=16). To determine dose effectiveness, the biological effective dose (BED) was calculated according to the following formula Gy10 = Total Dose (1 + fractional dose/α-β) using an α-β of 10. The above table presents univariate comparisons. For the entire series, 94% of patients derived a palliative response after treatment with irradiation. The median duration of palliation was 4 months (range, 2-80 months). With respect to overall response, only patients with metastases to the spinal cord were significantly less likely to derive palliation in multivariate analysis (p70) and the rate of CR (p=0.03). When entered as a dichotomous variable (e.g., relative to 39 Gy 10) increasing biologically effective dose was not associated with an increased rate of complete palliation; however, when entered as a continuous variable, increasing BED was strongly

  3. Radiation biology of low doses

    International Nuclear Information System (INIS)

    Present risk assessments and standards in radiation protection are based on the so-called linear no-threshold (LNT) dose - effect hypothesis, i.e., on a linear, proportional relationship between radiation doses and their effects on biological systems. This concept presupposes that any dose, irrespective of its level and time of occurrence, carries the same risk coefficient and, moreover, that no individual biological effects are taken into account. This contribution presents studies of low energy transfer (LET) radiation which deal with the risk of cancer to individual cells. According to the LNT hypothesis, the relationship for the occurrence of these potential effects should be constant over the dose range: successful repair, cell death, mutation with potential carcinogenesis. The results of the studies presented here indicate more differentiated effects as a function of dose application as far as damage to cellular DNA by ionizing radiation is concerned. At the same overall dose level, multiple exposures to low doses sometimes give rise to much smaller effects than those arising from one single exposure to the total dose. These adaptive effects of cells are known from other studies. The results of the study allow the conclusion to be drawn that non-linear relationships must be assumed to exist for the LET radiation considered. Correspondingly, the linear no-threshold hypothesis model should at least be reconsidered with respect to the low dose range in the light of recent biological findings. The inclusion of other topical research findings also could give rise to a new, revised, risk-oriented approach in radiological protection. (orig.)

  4. Biological effective doses in 300 patients undergoing therapy with 177Lu-octreotate

    International Nuclear Information System (INIS)

    Full text of publication follows. Aim: fractionated therapy with 177Lu-octreotate has been reported to be an effective treatment option for patients with generalized neuroendocrine tumors. The main aim of this study was to calculate the biological effective dose (BED) to the kidneys using an individualized dosimetry protocol, and to assess differences in the number of possible treatment cycles based on BED compared to those based on absorbed dose. Methods: a total of 148 female and 152 male patients with neuroendocrine tumors with high somatostatin receptor expression (grade 3 or 4) were included. After infusion of 7.4 GBq of 177Lu-octreotate SPECT/CT images over the abdomen were acquired at 24, 96 and 168 h after infusion. Absorbed dose to kidneys was calculated based on pharmacokinetic data obtained from SPECT/CT. From this the effective half-life of 177Lu-octreotate in the kidneys was estimated, and BED was calculated using the equation described by Barone et al. (1). Results and discussion: for a single treatment cycle of 7.4 GBq, median (1:st-3:rd quartiles) BED was 5.0 Gy (3.9-6.1) in the right kidney and 4.7 Gy (3.7-5.8) in the left kidney. For the same treatment cycle, BED was 9.0% (7.1-11.3) and 8.7% (7.0-10.9) higher than absorbed dose in right and left kidneys, respectively. In patients with high absorbed doses, BED could be more than 20% higher than absorbed dose. Assuming an absorbed dose limit of 23 Gy and a BED limit of 45 Gy to the kidneys, the possible number of treatment cycles was 5.4 (4.5-6.8) based on absorbed dose while using BED increased the number of possible cycles to 9.8 (8.1-12.5). Conclusions: although biological effective dose to the kidneys is higher than absorbed dose, use of BED to estimate the number of possible treatment cycles in 177Lu-octreotate therapy may allow for more treatment cycles than the use of absorbed dose. Refs: 1) Barone, R. et al. Patient-specific dosimetry in predicting renal toxicity with (90)Y

  5. Biological UV-doses and the effect on an ozone layer depletion

    International Nuclear Information System (INIS)

    Effective UV-doses were calculated based on the integrated product of the biological action spectrum and the solar radiation. The calculations included absorption and scattering of UV-radiation in the atmosphere, both for normal ozone conditions as well as for a depleted ozone layer. The effective annual UV-dose increases by approximately 4% per degree of latitude towards the equator. An ozone depletion of 1% increases the annual UV-dose by approximately 1% at 60o N. A large depletion of 50% over Scandinavia (60o N) would give this region an effective UV-dose similar to that obtained, with normal ozone conditions, at a latitude of 40o N (California or the Mediterranean countries). The Antarctic ozone hole increases the annual UV-dose by 20 to 25% which is a similar increase as that attained by moving 5 to 6 degrees of latitude nearer the equator. The annual UV-dose on higher latitudes is mainly determined by the summer values of ozone. Both the ozone values and the effective UV-doses vary from one year to another (within ±4%). No positive or negative trend is observed for Scandinavia from 1978 to 1988

  6. Biological modelling of the radiation dose escalation effect of regional hyperthermia in cervical cancer

    International Nuclear Information System (INIS)

    Locoregional hyperthermia combined with radiotherapy significantly improves locoregional control and overall survival for cervical tumors compared to radiotherapy alone. In this study biological modelling is applied to quantify the effect of radiosensitization for three cervical cancer patients to evaluate the improvement in equivalent dose for the combination treatment with radiotherapy and hyperthermia. The Linear-Quadratic (LQ) model extended with temperature-dependent LQ-parameters α and β was used to model radiosensitization by hyperthermia and to calculate the conventional radiation dose that is equivalent in biological effect to the combined radiotherapy and hyperthermia treatment. External beam radiotherapy planning was performed based on a prescription dose of 46Gy in 23 fractions of 2Gy. Hyperthermia treatment using the AMC-4 system was simulated based on the actual optimized system settings used during treatment. The simulated hyperthermia treatments for the 3 patients yielded a T50 of 40.1 °C, 40.5 °C, 41.1 °C and a T90 of 39.2 °C, 39.7 °C, 40.4 °C, respectively. The combined radiotherapy and hyperthermia treatment resulted in a D95 of 52.5Gy, 55.5Gy, 56.9Gy in the GTV, a dose escalation of 7.3–11.9Gy compared to radiotherapy alone (D95 = 45.0–45.5Gy). This study applied biological modelling to evaluate radiosensitization by hyperthermia as a radiation-dose escalation for cervical cancer patients. This model is very useful to compare the effectiveness of different treatment schedules for combined radiotherapy and hyperthermia treatments and to guide the design of clinical studies on dose escalation using hyperthermia in a multi-modality setting

  7. Biology responses to low dose radiation

    International Nuclear Information System (INIS)

    Biology responses to low dose radiation is the most important problem of medical radiation and radiation protection. The especial mechanism of low dose or low dose rate induced cell responses, has been found independent with linear no-threshold model. This article emphasize to introduce low dose or low dose rate induced biology responses of adaptive response, by-effect, super-sensitivity and genomic instability. (authors)

  8. Influence of variations in dose and dose rates on biological effects of inhaled beta-emitting radionuclides

    International Nuclear Information System (INIS)

    The biological effects of inhaled β-emitting radionuclides, 90Y, 91Y, 144Ce and 90Sr, are being investigated in beagle dogs that received single acute exposures at 12 to 14 months of age. The aerosols studied have included 91YC13,144CeC13, 90SrC12, and 90Y, 91Y, 144Ce or 90Sr in aluminosilicate particles. Thus, 91YCl3, 144CeCl3 and the aluminosilicate containing radionuclide particles all resulted in significant exposures to lung; 91YC13, 144CeC13 an 90SrC12 resulted in significant exposures to bone; 91YC13 and 144 CeC13 resulted in significant exposures to liver. The higher initial doserate exposures have been more effective than low dose-rate exposures on a per-rad basis in producing early effects. To date (144CeO2, it was observed that, on a μCi initial lung burden per kilogram body weight basis, mice did not develop pulmonary tumours whereas beagle dogs did. To fid out the reason for this observation mice have been repeatedly exposed by inhalation to 144CeO2 to maintain lung burdens of 144Ce that resulted in radiation dose rates similar to that observed in beagle dogs. Several of the repeatedly exposed mice developed malignant pulmonary tumours. Thus, with similar dose rates and cumulative doses to the lung, mice and dogs responded in a similar manner to chronic β radiation

  9. Early biological effects of low doses of ionizing radiation on yeast cells

    International Nuclear Information System (INIS)

    The biological effectiveness of different radiation types for variety organisms requires further study. For fundamental studies of this problem it is worthwhile to use the most thoroughly investigated biological objects, for example, yeasts. The yeast Saccharomyces cerevisiae was used as the test eukaryotic organism which gives the experimenter complete control over its chemical and physical environment. The aim of the study consisted in comparative analysis of early effects induced by low doses of low LET (60Co and 137Cs) and high LET ( α-particles 239Pu, neutrons) radiation on eukaryotic cells (cell survival about 100%). Biological effects of low doses of ionizing radiation were studied by two criteria: 1.delay of cell division and kinetics of yeast cells micro-colonies formation; 2.morphology of micro-colonies at different temperature. The results have shown that only small part of irradiated cell population (∼10%) divided at the same rate as unirradiated cells. Other part of cells had a delayed division. Unirradiated control cells formed typical micro-colonies at the solid nutrient media (YEPD) after 10 15 h of incubation. The fraction of cells population (20- 25%) exposed to low doses of?-particles or neutrons formed spectrum of untypical micro-colonies for the same incubation time, which consisted of small number of larger and more elongated cells. Some of these micro-colonies had 10 50 cells were of exotic forms ('spider'), differed from other micro-colonies in population. Using this method we can reveal an early response of cells at very low doses (survival about 100%) and determine the number non-lethally damaged cells. (author)

  10. Comparison of breast sequential and simultaneous integrated boost using the biologically effective dose volume histogram (BEDVH)

    International Nuclear Information System (INIS)

    A method is presented to radiobiologically compare sequential (SEQ) and simultaneously integrated boost (SIB) breast radiotherapy. The method is based on identically prescribed biologically effective dose (iso-BED) which was achieved by different prescribed doses due to different fractionation schemes. It is performed by converting the calculated three-dimensional dose distribution to the corresponding BED distribution taking into consideration the different number of fractions for generic α/β ratios. A cumulative BED volume histogram (BEDVH) is then derived from the BED distribution and is compared for the two delivery schemes. Ten breast cancer patients (4 right-sided and 6 left-sided) were investigated. Two tangential intensity modulated whole breast beams with two other oblique (with different gantry angles) beams for the boost volume were used. The boost and the breast target volumes with either α/β = 10 or 3 Gy, and ipsi-lateral and contra-lateral lungs, heart, and contra-lateral breast as organs at risk (OARs) with α/β = 3 Gy were compared. Based on the BEDVH comparisons, the use of SIB reduced the biological breast mean dose by about 3 %, the ipsi-lateral lung and heart by about 10 %, and contra-lateral breast and lung by about 7 %. BED based comparisons should always be used in comparing plans that have different fraction sizes. SIB schemes are dosimetrically more advantageous than SEQ in breast target volume and OARs for equal prescribed BEDs for breast and boost

  11. Relative biological effectiveness of 125I seeds for low-dose-rate irradiation of PANC-1

    International Nuclear Information System (INIS)

    Objective: To investigate the relative biological effectiveness(RBE) of National Model 6711 125I seeds and the response patterns of PANC-1 exposed to 125I seeds irradiation. Methods: PANC-1 cells in exponential growth were irradiated at initial dose rate of 2.59 cGy/h in vitro and exposed to 1, 2, 4, 6, 8 and 10 Gy. Meanwhile, the other part of cells were exposed to the same doses by 60Co at dose rate of 2.21 Gy/min. After irradiation, the cells were stained by trypan blue to measure the cellular mortality rate and to compare the changes along with plating times of 12, 24, 48 and 72 h after 4 Gy. The colonies were counted to obtain the plating efficiencies by colony-forming assay and the cell surviving faction was calculated to plot cell survival curves, and RBE of 125I seeds relative to 60Co was determined. Results: The cell death rate for continuous low- dose-rate (LDR) irradiation by 125I seeds was greater than 60Co at the same doses above or equal to 4 Gy. After 4 Gy irradiation, the cellular mortality rates were increased with times. The difference was significant between 125I seeds and 60Co. The survival fractions of 125I were lower than those of 60Co, and the RBE of 125I relative to 60Co was determined to be 1.45. Conclusion: The cell-killing effects for continuous low-dose-rate (LDR) irradiation by 125I seeds are greater than acute high-dose-rate of 60Co. (authors)

  12. The debate about effects of low doses: from epidemiology to biology

    International Nuclear Information System (INIS)

    The validity of the linear no-threshold dose-carcinogenic effect relationship used in radio protection was called into question by the discovery during the past 15 years of three cell mechanisms for protection of the genome: antioxidant systems that react to oxidative stress, DNA repair, and elimination by death of cells with damaged DNA, either when the DNA repair mechanisms were not activated because of the very low dose (or dose rate) or by apoptosis for higher doses because the DNA damage was not appropriately repaired. It is now clear that these mechanisms are more effective for low closes (<100 mSv) than for doses exceeding several hundred mSv, therefore the biological data are no longer compatible with the hypothesis of a linear no-threshold relationship (LNT). This conclusion is consistent with the experimental (both in vivo and in vitro) and epidemiologic data, which reveal no harmful effects for doses less than approximately 100 mSv. Accordingly, the principal conclusion that has been drawn from the LNT, that is, that any close, however low, is carcinogenic, is called into question because it no longer has a scientific basis. This dogma, which has been extended to all carcinogenic agents, causes diffuse anxiety in all those exposed to carcinogenic agents, even at very low concentrations. It has led to the refusal of some to submit to radiologic examinations (such as mammographic screening for breast cancer), with sometimes regrettable medical consequences. After the Chernobyl catastrophe it caused panic and the evacuation of vast territories where natural irradiation was only very slightly increased, with social and medical consequences due to displacement of more than 200,000 people. It is therefore urgent to reconsider it. (author)

  13. The biological effect of large single doses: a possible role for non-targeted effects in cell inactivation.

    Directory of Open Access Journals (Sweden)

    Marlon R Veldwijk

    Full Text Available BACKGROUND AND PURPOSE: Novel radiotherapy techniques increasingly use very large dose fractions. It has been argued that the biological effect of large dose fractions may differ from that of conventional fraction sizes. The purpose was to study the biological effect of large single doses. MATERIAL AND METHODS: Clonogenic cell survival of MCF7 and MDA-MB-231 cells was determined after direct X-ray irradiation, irradiation of feeder cells, or transfer of conditioned medium (CM. Cell-cycle distributions and the apoptotic sub-G1 fraction were measured by flow cytometry. Cytokines in CM were quantified by a cytokine antibody array. γH2AX foci were detected by immunofluorescence microscopy. RESULTS: The surviving fraction of MCF7 cells irradiated in vitro with 12 Gy showed an 8.5-fold decrease (95% c.i.: 4.4-16.3; P<0.0001 when the density of irradiated cells was increased from 10 to 50×10(3 cells per flask. Part of this effect was due to a dose-dependent transferrable factor as shown in CM experiments in the dose range 5-15 Gy. While no effect on apoptosis and cell cycle distribution was observed, and no differentially expressed cytokine could be identified, the transferable factor induced prolonged expression of γH2AX DNA repair foci at 1-12 h. CONCLUSIONS: A dose-dependent non-targeted effect on clonogenic cell survival was found in the dose range 5-15 Gy. The dependence of SF on cell numbers at high doses would represent a "cohort effect" in vivo. These results support the hypothesis that non-targeted effects may contribute to the efficacy of very large dose fractions in radiotherapy.

  14. A perspective on dose limits and biological effects of radiation on the foetus

    International Nuclear Information System (INIS)

    The potential biological effects of radiation doses to pregnant workers consistent with Canadian regulations and ICRP recommendations are reviewed. These hazards are in general very small compared to the normal hazards associated with human development. Potential carcinogenic effects may well be the major biological problem associated with foetal exposures. Radiation hazards to the embryo are essentially zero for exposures occurring during the first four weeks after conception. The new ICRP recommendations on exposures of pregnant women suggest a number of problems to be solved. These include (a) improvements in current methods of measuring both external radiation doses and intakes of certain radionuclides in Canada, (b) further research on the metabolism of radionuclides in pregnant women, including concentrations of certain radionuclides in foetal/embryonic tissues and also in adjacent tissues of the mother; and (c) socio-economic problems that may be involved in the implementation of the recommendations on exposures of pregnant workers, particularly in small facilities such as nuclear medicine departments in hospitals. (Author) 3 tabs., 21 refs

  15. The combined biological effects of low dose radiation, carbon monoxide, benzene and noise on rats

    International Nuclear Information System (INIS)

    Objective: To investigate the combined biological effects of low dose radiation, carbon monoxide,benzene and noise on rats. Methods: Sixteen male SD rats were randomly divided into experiment group and control group. The experiment group was exposed to carbon monoxide, benzene, low dose radiation and noise daily, the control group was in common environment. Peripheral blood, organ index, and marrow DNA content were detected. Two-dimensional electrophoresis (2-DE) was performed on serum protein analysis. Differential expressed proteins were identified by a matrix assisted laser desorption/ionization time of flight mass spectrometry (MAIDI-TOF-MS). Results: Compared to control group, the liver index, spleen index, thymus index, leukocytes, platelets count, and marrow DNA content of the experiment group were decreased significantly (t=2.732, 4.141, 3.053, 2.211, 2.668, 11.592, P<0.05). 12 altered proteins were detected and through identification, 3 proteins were definite in terms of serum amyloid A-4 protein (SAA4), trichoplein keratin filament-binding protein (TCHP) and tubulin alpha-4A chain (TUBA4A). Conclusions: The hematopoietic system and immune system of rats are damaged significantly with the changes of several serum protein expressions by the combined exposure of low dose radiation, carbon monoxide, benzene and noise. This study may provide new information for the mechanism of the combination effects. (authors)

  16. Low-dose neutron dose response of zebrafish embryos obtained from the Neutron exposure Accelerator System for Biological Effect Experiments (NASBEE) facility

    International Nuclear Information System (INIS)

    The dose response of embryos of the zebrafish, Danio rerio, irradiated at 5 h post fertilization (hpf) by 2-MeV neutrons with ≤100 mGy was determined. The neutron irradiations were made at the Neutron exposure Accelerator System for Biological Effect Experiments (NASBEE) facility in the National Institute of Radiological Sciences (NIRS), Chiba, Japan. A total of 10 neutron doses ranging from 0.6 to 100 mGy were employed (with a gamma-ray contribution of 14% to the total dose), and the biological effects were studied through quantification of apoptosis at 25 hpf. The responses for neutron doses of 10, 20, 25, and 50 mGy approximately fitted on a straight line, while those for neutron doses of 0.6, 1 and 2.5 mGy exhibited neutron hormetic effects. As such, hormetic responses were generically developed by different kinds of ionizing radiations with different linear energy transfer (LET) values. The responses for neutron doses of 70 and 100 mGy were significantly below the lower 95% confidence band of the best-fit line, which strongly suggested the presence of gamma-ray hormesis. - Highlights: • Neutron dose response was determined for embryos of the zebrafish, Danio rerio. • Neutron doses of 0.6, 1 and 2.5 mGy led to neutron hormetic effects. • Neutron doses of 70 and 100 mGy accompanied by gamma rays led to gamma-ray hormesis

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

    International Nuclear Information System (INIS)

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

  18. Biological effects

    International Nuclear Information System (INIS)

    Following an introduction into the field of cellular radiation effect considering the most important experimental results, the biological significance of the colony formation ability is brought out. The inactivation concept of stem cells does not only prove to be good, according to the present results, in the interpretation of the pathogenesis of acute radiation effects on moult tissue, it also enables chronicle radiation injuries to be interpreted through changes in the fibrous part of the organs. Radiation therapy of tumours can also be explained to a large extent by the radiation effect on the unlimited reproductiveness of tumour cells. The more or less similar dose effect curves for healthy and tumour tissue in practice lead to intermittent irradiation. The dependence of the intermittent doses and intervals on factors such as Elkind recovery, synchronisation, redistribution, reoxygenation, repopulation and regeneration are reviewed. (ORU/LH)

  19. Biological dosimetry - Dose estimation method using biomakers

    International Nuclear Information System (INIS)

    The individual radiation dose estimation is an important step in the radiation risk assessment. In case of radiation incident or radiation accident, sometime, physical dosimetry method can not be used for calculating the individual radiation dose, the other complement method such as biological dosimetry is very necessary. This method is based on the quantitative specific biomarkers induced by ionizing radiation, such as dicentric chromosomes, translocations, micronuclei... in human peripheral blood lymphocytes. The basis of the biological dosimetry method is the close relationship between the biomarkers and absorbed dose or dose rate; the effects of in vitro and in vivo are similar, so it is able to generate the calibration dose-effect curve in vitro for in vivo assessment. Possibilities and perspectives for performing biological dosimetry method in radiation protection area are presented in this report. (author)

  20. Low doses of ionizing radiation: Biological effects and regulatory control. Invited papers and discussions. Proceedings of an international conference

    International Nuclear Information System (INIS)

    The levels and biological effects resulting from exposure to ionizing radiation are continuously reviewed by the United Nations Committee on the Effects of Atomic Radiation (UNSCEAR). Since its creation in 1928, the International Commission on Radiological Protection (ICRP) has issued recommendations on protection against ionizing radiation. The UNSCEAR estimates and the ICRP recommendations have served as the basis for national and international safety standards on radiation safety, including those developed by the International Atomic Energy Agency (IAEA) and the World Health Organization (WHO). Concerning health effects of low doses of ionizing radiation, the international standards are based on the plausible assumption that, above the unavoidable background radiation dose, the probability of effects increases linearly with dose, i.e. on a 'linear, no threshold' (LNT) assumption. However, in recent years the biological estimates of health effects of low doses of ionizing radiation and the regulatory approach to the control of low level radiation exposure have been much debated. To foster information exchange on the relevant issues, an International Conference on Low Doses of Ionizing Radiation: Biological Effects and Regulatory Control, jointly sponsored by the IAEA and WHO in co-operation with UNSCEAR, was held from 17-21 November 1997 at Seville, Spain. These Proceedings contain the invited special reports, keynote papers, summaries of discussions, session summaries and addresses presented at the opening and closing of the Conference

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

    International Nuclear Information System (INIS)

    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 D2. (author)

  2. Interaction between the biological effects of high- and low-LET radiation dose components in a mixed field exposure

    DEFF Research Database (Denmark)

    Mason, Anna J.; Giusti, Valerio; Green, Stuart;

    2011-01-01

    The relative biological effectiveness of two epithermal neutron sources, a reactor based source at Studsvik, Sweden, and a proton accelerator-based source in Birmingham, UK, was studied in relation to the proportional absorbed dose distribution as a function of neutron energy. Evidence for any...

  3. Radiosensitivity of Nicotiana protoplasts. Action on cell; cycle effects of low dose and fractionated irradiations; biological repair

    International Nuclear Information System (INIS)

    Leaf protoplasts of Nicotiana plumbaginifolia and Nicotiana sylvestris demonstrate five main qualities: they can be maintained as haploid lines; they constitute starting populations with a remarkable cytological homogeneity; they show a transient initial lag-phase; they yield very high plating efficiencies and retain permanently a complete differentiation capacity; being derived of a cell wall, they appear well adapted for fusion experiments or enzymatic dosages. The resumption of mitotic activity was followed by cytophotometric measurements, labelling experiments, nuclear sizing and enzymatic assays. The action of 5 Gy gamma-ray irradiations delayed entrance in the S-phase, provoked an otherwise not verified dependency between transcription, translation and protein synthesis, increased nuclear volumes in the G2-phase, and slightly stimulated the activity of a repair enzyme. The plating efficiency was a sensitive end-point which allowed the evaluation of the biological effectiveness of low to medium radiation-doses after gamma-ray and fast neutron irradiations. The neutron dose-RBE relationship increased from 3 to 25 when the dose decreased from 5 Gy to 5 mGy. When fractionated into low single doses only, a neutron dose of 300 mGy markedly increased its biological effectiveness: this phenomenon could not be explained by cell progression, and necessitated additional hypotheses involving other mechanisms in the specific action of low radiation doses. Radiation-induced UDS was measured in presence of aphidicolin. A beta-like DNA-polymerase was shown to be definitely involved in nuclear repair synthesis

  4. Extension of the biological effective dose to the MIRD schema and possible implications in radionuclide therapy dosimetry

    International Nuclear Information System (INIS)

    In dosimetry-based treatment planning protocols, patients with rapid clearance of the radiopharmaceutical require a larger amount of initial activity than those with slow clearance to match the absorbed dose to the critical organ. As a result, the dose-rate to the critical organ is higher in patients with rapid clearance and may cause unexpected toxicity compared to patients with slow clearance. In order to account for the biological impact of different dose-rates, radiobiological modeling is beginning to be applied to the analysis of radionuclide therapy patient data. To date, the formalism used for these analyses is based on kinetics derived from activity in a single organ, the target. This does not include the influence of other source organs to the dose and dose-rate to the target organ. As a result, only self-dose irradiation in the target organ contributes to the dose-rate. In this work, the biological effective dose (BED) formalism has been extended to include the effect of multiple source organ contributions to the net dose-rate in a target organ. The generalized BED derivation has been based on the Medical Internal Radionuclide Dose Committee (MIRD) schema assuming multiple source organs following exponential effective clearance of the radionuclide. A BED-based approach to determine the largest safe dose to critical organs has also been developed. The extended BED formalism is applied to red marrow dosimetry, as well as kidney dosimetry considering the cortex and the medulla separately, since both those organs are commonly dose limiting in radionuclide therapy. The analysis shows that because the red marrow is an early responding tissue (high α/β), it is less susceptible to unexpected toxicity arising from rapid clearance of high levels of administered activity in the marrow or in the remainder of the body. In kidney dosimetry, the study demonstrates a complex interplay between clearance of activity in the cortex and the medulla, as well as the initial

  5. Compatibility of the Linear-Quadratic Formalism and Biologically Effective Dose Concept to High-Dose-Per-Fraction Irradiation in a Murine Tumor

    International Nuclear Information System (INIS)

    Purpose: To evaluate the compliance of linear-quadratic (LQ) model calculations in the high-dose range as used in stereotactic irradiation in a murine tumor model. Methods and Materials: Female 10-week-old Balb/c mice bearing 1-cm-diameter EMT6 tumors in the hind legs were used. Single doses of 10–25 Gy were compared with 2–5 fractions of 4–13 Gy given at 4-hour intervals. Cell survival after irradiation was determined by an in vivo–in vitro assay. Using an α/β ratio determined for in vitro EMT6 cells and the LQ formalism, equivalent single doses for the hypofractionated doses were calculated. They were then compared with actually measured equivalent single doses for the hypofractionated doses. These fractionation schedules were also compared simultaneously to investigate the concordance/divergence of dose–survival curves plotted against actual radiation doses and biologically effective doses (BED). Results: Equivalent single doses for hypofractionated doses calculated from LQ formalism were lower than actually measured doses by 21%–31% in the 2- or 3-fraction experiments and by 27%–42% in the 4- or 5-fraction experiments. The differences were all significant. When a higher α/β ratio was assumed, the discrepancy became smaller. In direct comparison of the 2- to 5-fraction schedules, respective dose–response curves almost overlapped when cell survival was plotted against actual radiation doses. However, the curves tended to shift downward by increasing the fraction number when cell survival was plotted against BED calculated using an α/β ratio of 3.5 Gy for in vitro EMT6 cells. Conclusion: Conversion of hypofractionated radiation doses to single doses using the LQ formalism underestimated the in vivo effect of hypofractionated radiation by approximately 20%–40%. The discrepancy appeared to be larger than that seen in the previous in vitro study and tended to increase with the fraction number. BED appeared to be an unreliable measure of tumor

  6. Biological effectiveness on live cells of laser driven protons at dose rates exceeding 109 Gy/s

    International Nuclear Information System (INIS)

    The ultrashort duration of laser-driven multi-MeV ion bursts offers the possibility of radiobiological studies at extremely high dose rates. Employing the TARANIS Terawatt laser at Queen's University, the effect of proton irradiation at MeV-range energies on live cells has been investigated at dose rates exceeding 109 Gy/s as a single exposure. A clonogenic assay showed consistent lethal effects on V-79 live cells, which, even at these dose rates, appear to be in line with previously published results employing conventional sources. A Relative Biological Effectiveness (RBE) of 1.4±0.2 at 10% survival is estimated from a comparison with a 225 kVp X-ray source.

  7. A regulatable AAV vector mediating GDNF biological effects at clinically-approved sub-antimicrobial doxycycline doses

    Science.gov (United States)

    Chtarto, Abdelwahed; Humbert-Claude, Marie; Bockstael, Olivier; Das, Atze T; Boutry, Sébastien; Breger, Ludivine S; Klaver, Bep; Melas, Catherine; Barroso-Chinea, Pedro; Gonzalez-Hernandez, Tomas; Muller, Robert N; DeWitte, Olivier; Levivier, Marc; Lundberg, Cecilia; Berkhout, Ben; Tenenbaum, Liliane

    2016-01-01

    Preclinical and clinical data stress the importance of pharmacologically-controlling glial cell line-derived neurotrophic factor (GDNF) intracerebral administration to treat PD. The main challenge is finding a combination of a genetic switch and a drug which, when administered at a clinically-approved dose, reaches the brain in sufficient amounts to induce a therapeutic effect. We describe a highly-sensitive doxycycline-inducible adeno-associated virus (AAV) vector. This vector allowed for the first time a longitudinal analysis of inducible transgene expression in the brain using bioluminescence imaging. To evaluate the dose range of GDNF biological activity, the inducible AAV vector (8.0 × 109 viral genomes) was injected in the rat striatum at four delivery sites and increasing doxycycline doses administered orally. ERK/Akt signaling activation as well as tyrosine hydroxylase downregulation, a consequence of long-term GDNF treatment, were induced at plasmatic doxycycline concentrations of 140 and 320 ng/ml respectively, which are known not to increase antibiotic-resistant microorganisms in patients. In these conditions, GDNF covered the majority of the striatum. No behavioral abnormalities or weight loss were observed. Motor asymmetry resulting from unilateral GDNF treatment only appeared with a 2.5-fold higher vector and a 13-fold higher inducer doses. Our data suggest that using the herein-described inducible AAV vector, biological effects of GDNF can be obtained in response to sub-antimicrobial doxycycline doses. PMID:27069954

  8. BEDVH--A method for evaluating biologically effective dose volume histograms: Application to eye plaque brachytherapy implants

    Energy Technology Data Exchange (ETDEWEB)

    Gagne, Nolan L.; Leonard, Kara L.; Huber, Kathryn E.; Mignano, John E.; Duker, Jay S.; Laver, Nora V.; Rivard, Mark J. [Department of Radiation Oncology, Tufts University School of Medicine, Boston, Massachusetts 02111 (United States); Department of Ophthalmology, Tufts University School of Medicine, Boston, Massachusetts 02111 (United States); Departments of Ophthalmology and Pathology, Tufts University School of Medicine, Boston, Massachusetts 02111 (United States); Department of Radiation Oncology, Tufts University School of Medicine, Boston, Massachusetts 02111 (United States)

    2012-02-15

    Purpose: A method is introduced to examine the influence of implant duration T, radionuclide, and radiobiological parameters on the biologically effective dose (BED) throughout the entire volume of regions of interest for episcleral brachytherapy using available radionuclides. This method is employed to evaluate a particular eye plaque brachytherapy implant in a radiobiological context. Methods: A reference eye geometry and 16 mm COMS eye plaque loaded with {sup 103}Pd, {sup 125}I, or {sup 131}Cs sources were examined with dose distributions accounting for plaque heterogeneities. For a standardized 7 day implant, doses to 90% of the tumor volume ( {sub TUMOR}D{sub 90}) and 10% of the organ at risk volumes ( {sub OAR}D{sub 10}) were calculated. The BED equation from Dale and Jones and published {alpha}/{beta} and {mu} parameters were incorporated with dose volume histograms (DVHs) for various T values such as T = 7 days (i.e., {sub TUMOR} {sup 7}BED{sub 10} and {sub OAR} {sup 7}BED{sub 10}). By calculating BED throughout the volumes, biologically effective dose volume histograms (BEDVHs) were developed for tumor and OARs. Influence of T, radionuclide choice, and radiobiological parameters on {sub TUMOR}BEDVH and {sub OAR}BEDVH were examined. The nominal dose was scaled for shorter implants to achieve biological equivalence. Results: {sub TUMOR}D{sub 90} values were 102, 112, and 110 Gy for {sup 103}Pd, {sup 125}I, and {sup 131}Cs, respectively. Corresponding {sub TUMOR} {sup 7}BED{sub 10} values were 124, 140, and 138 Gy, respectively. As T decreased from 7 to 0.01 days, the isobiologically effective prescription dose decreased by a factor of three. As expected, {sub TUMOR} {sup 7}BEDVH did not significantly change as a function of radionuclide half-life but varied by 10% due to radionuclide dose distribution. Variations in reported radiobiological parameters caused {sub TUMOR} {sup 7}BED{sub 10} to deviate by up to 46%. Over the range of {sub OAR

  9. Dose estimation by biological methods

    International Nuclear Information System (INIS)

    The human being is exposed to strong artificial radiation sources, mainly of two forms: the first is referred to the occupationally exposed personnel (POE) and the second, to the persons that require radiological treatment. A third form less common is by accidents. In all these conditions it is very important to estimate the absorbed dose. The classical biological dosimetry is based in the dicentric analysis. The present work is part of researches to the process to validate the In situ Fluorescent hybridation (FISH) technique which allows to analyse the aberrations on the chromosomes. (Author)

  10. Biological effects of low doses of ionizing radiation: Conflict between assumptions and observations

    International Nuclear Information System (INIS)

    Recent epidemiological data on cancer incidence among the A-bomb survivors and more importantly experimental studies in cell and molecular radiobiology do not lend unequivocal support to the ''linear, no threshold'' (LNT) hypothesis; in fact, the discernible evidence that low and high doses of ionizing radiations induce qualitatively different/opposite effects cannot be summarily rejected. A time has come to examine the mechanistic aspects of ''radiation hormesis'' and ''radioadaptive response'' seriously rather than proclaiming one's profound disbelief about these phenomena. To put the discussion in a serious scientific mode, we briefly catalogue here reports in the literature on gene expression differentially influenced by low and high doses. These are not explicable in terms of the current radiation paradigm. (author)

  11. Influence of dose rate on fast neutron OER and biological effectiveness determined for growth inhibition in Vicia faba

    International Nuclear Information System (INIS)

    The influence of dose rate on the effectiveness of a neutron irradiation was investigated using growth inhibition in Vicia faba bean roots as biological system. d(50)+Be neutron beams produced at the cyclotron CYCLONE of the University of Louvain-la-Neuve were used, at high and low dose rate, by modifying the deuteron beam current. When decreasing the dose rate from 0.14 Gy.min-1 to 0.2 Gy.h-1, the effectiveness of the neutrons decreased down to 0.84+-0.05 (dose ratio, at high and low dose rate, Dsub(high)/Dsub(low), producing equal biological effect). Control irradiation, with 60Co γ-rays, indicated a similar reduction in effectiveness (0.84+-0.03) when decreasing dose rate from 0,6 Gy.min-1 to 0.7 Gy.h-1. In previous experiments, on the same Vicia faba system, higher RBE values were observed for 252Cf neutrons, at low dose rate (RBE=8.3), compared to different neutron beams actually used in external beam therapy (RBE=3.2-3.6 for d(50)+Be, p(75)+Be and 15 MeV (d, T) neutrons). According to present results, this higher RBE has to be related to lower energy of the 252Cf neutron spectrum (2 MeV), since the influence of dose rate was shown to be small. As far as OER is concerned, for d(50)+Be neutrons, it decreases from 1.65+-0.12 to 1.59+-0.09 when decreasing close rate from 0.14 Gy.min-1 to 0.2 Gy.h-1. Control irradiations with 60Co γ-rays have shown an OER decrease from 2.69+-0.08 to 2.55+-0.11 when decreasing dose rate from 0.6 Gy.min-1 to 0.7 Gy.h-1. These rather small OER reductions are within the statistical fluctuations. (orig.)

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

    International Nuclear Information System (INIS)

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

  13. Relative Biological Effectiveness of HZE Fe Ions for Induction ofMicro-Nuclei at Low Doses

    Energy Technology Data Exchange (ETDEWEB)

    Groesser, Torsten; Chun, Eugene; Rydberg, Bjorn

    2007-01-16

    Dose-response curves for induction of micro-nuclei (MN) was measured in Chinese hamster V79 and xrs6 (Ku80-) cells and in human mammary epithelial MCF10A cells in the dose range of 0.05-1 Gy. The Chinese Hamster cells were exposed to 1 GeV/u Fe ions, 600 MeV/u Fe ions, and 300 MeV/u Fe ions (LETs of 151, 176 and 235 keV/{micro}m respectively) as well as with 320 kVp X-rays as reference. Second-order polynomials were fitted to the induction curves and the initial slopes (the alpha values) were used to calculate RBE. For the repair proficient V79 cells the RBE at these low doses increased with LET. The values obtained were 3.1 (LET=151 keV/{micro}m), 4.3 (LET = 176 keV/{micro}m) and 5.7 (LET = 235 keV/{micro}m), while the RBE was close to 1 for the repair deficient xrs6 cells regardless of LET. For the MCF10A cells the RBE was determined for 1 GeV/u Fe ions and found to be 5.4, slightly higher than for V79 cells. To test the effect of shielding, the 1 GeV/u Fe ion beam was intercepted by various thickness of high-density polyethylene plastic absorbers, which resulted in energy loss and fragmentation. It was found that the MN yield for V79 cells placed behind the absorbers decreased in proportion to the decrease in dose both before and after the Fe ion Bragg peak (excluding the area around the Fe-ion Bragg peak itself), indicating that RBE did not change significantly due to shielding. At the Bragg peak the effectiveness for MN formation per unit dose was decreased, indicating an 'overkill' effect by low-energy very high-LET Fe ions.

  14. The debate about effects of low doses: from epidemiology to biology; Le debat sur les effets des faibles doses: de l'epidemiologie a la biologie

    Energy Technology Data Exchange (ETDEWEB)

    Tubiana, M. [Institut Gustave Roussy, 94 - Villejuif (France); Academie de Medecine, 75 - Paris (France); Centre Antoine Beclere, 75 - Paris (France)

    2007-01-15

    The validity of the linear no-threshold dose-carcinogenic effect relationship used in radio protection was called into question by the discovery during the past 15 years of three cell mechanisms for protection of the genome: antioxidant systems that react to oxidative stress, DNA repair, and elimination by death of cells with damaged DNA, either when the DNA repair mechanisms were not activated because of the very low dose (or dose rate) or by apoptosis for higher doses because the DNA damage was not appropriately repaired. It is now clear that these mechanisms are more effective for low closes (<100 mSv) than for doses exceeding several hundred mSv, therefore the biological data are no longer compatible with the hypothesis of a linear no-threshold relationship (LNT). This conclusion is consistent with the experimental (both in vivo and in vitro) and epidemiologic data, which reveal no harmful effects for doses less than approximately 100 mSv. Accordingly, the principal conclusion that has been drawn from the LNT, that is, that any close, however low, is carcinogenic, is called into question because it no longer has a scientific basis. This dogma, which has been extended to all carcinogenic agents, causes diffuse anxiety in all those exposed to carcinogenic agents, even at very low concentrations. It has led to the refusal of some to submit to radiologic examinations (such as mammographic screening for breast cancer), with sometimes regrettable medical consequences. After the Chernobyl catastrophe it caused panic and the evacuation of vast territories where natural irradiation was only very slightly increased, with social and medical consequences due to displacement of more than 200,000 people. It is therefore urgent to reconsider it. (author)

  15. The different biological effects of single, fractionated and continuous low dose rate irradiation on CL187 colorectal cancer cells

    International Nuclear Information System (INIS)

    To determine the biological effectiveness of single, fractionated and continuous low dose rate irradiation on the human colorectal cancer cell line CL187 in vitro and explore the cellular mechanisms. The CL187 cells were exposed to radiation of 6 MV X-ray at a high dose rate of 4Gy/min and 125I seed at a low dose rate of 2.77 cGy/h. Three groups were employed: single dose radiation group (SDR), fractionated dose radiation group (FDR) by 2Gy/f and continuous low dose rate radiation group (CLDR). Four radiation doses 2, 4, 6 and 8Gy were chosen and cells without irradiation as the control. The responses of CL187 cells to distinct modes of radiation were evaluated by the colony-forming assay, cell cycle progression as well as apoptosis analysis. In addition, we detected the expression patterns of DNA-PKcs, Ku70 and Ku80 by Western blotting. The relative biological effect for 125I seeds compared with 6 MV X-ray was 1.42. 48 hrs after 4Gy irradiation, the difference between proportions of cells at G2/M phase of SDR and CLDR groups were statistically significant (p = 0.026), so as the FDR and CLDR groups (p = 0.005). 48 hrs after 4Gy irradiation, the early apoptotic rate of CLDR group was remarkably higher than SDR and FDR groups (CLDR vs. SDR, p = 0.001; CLDR vs. FDR, p = 0.02), whereas the late apoptotic rate of CLDR group increased significantly compared with SDR and FDR group (CLDR vs. SDR, p = 0.004; CLDR vs. FDR, p = 0.007). Moreover, DNA-PKcs and Ku70 expression levels in CLDR-treated cells decreased compared with SDR and FDR groups. Compared with the X-ray high dose rate irradiation, 125I seeds CLDR showed more effective induction of cell apoptosis and G2/M cell cycle arrest. Furthermore, 125I seeds CLDR could impair the DNA repair capability by down-regulating DNA-PKcs and Ku70 expression

  16. European low-dose radiation risk research strategy: future of research on biological effects at low doses

    International Nuclear Information System (INIS)

    In 2009, the European High Level and Expert Group identified key policy and scientific questions to be addressed through a strategic research agenda for low-dose radiation risk. This initiated the establishment of a European Research Platform, called MELODI (Multidisciplinary European Low Dose Research Initiative). In 2010, the DoReMi Network of Excellence was launched in the Euratom 7. Framework Programme. DoReMi has acted as an operational tool for the sustained development of the MELODI platform during its early years. A long-term Strategic Research Agenda for European low-dose radiation risk research has been developed by MELODI. Strategic planning of DoReMi research activities is carried out in close collaboration with MELODI. The research priorities for DoReMi are designed to focus on objectives that are achievable within the 6-y lifetime of the project and that are in areas where stimulus and support can help progress towards the longer-term strategic objectives. (authors)

  17. Low dose irradiation and biological defense mechanisms

    International Nuclear Information System (INIS)

    It has been generally accepted in the context of radiation protection that ionizing radiation has some adverse effect even at low doses. However, epidemiological studies of human populations cannot definitively show its existence or absence. Furthermore, recent studies of populations living in areas of different background radiation levels reported some decrease in adverse health effects at high background levels. Genetic studies of atomic bomb survivors failed to produce statistically significant findings on the mutagenic effects of ionizing radiation. A British study however, suggests that a father's exposure to low dose radiation on the job may increase his children's risk of leukemia. On the other hand, many experimental studies have raised the possibility that low doses of ionizing radiation may not be harmful or may even produce stimulating or adaptive responses. The term 'hormesis' has come to be used to describe these phenomena produced by low doses of ionizing radiation when they were beneficial for the organisms studied. At the end of the International Conference on Low Dose Irradiation one conclusion appeared to be justified: radiation produces an adaptive response, though it is not universally detected yet. The conference failed to obtain any consensus on risk assessment at low doses, but raised many problems to be dealt with by future studies. The editors therefore believe that the Proceedings will be useful for all scientists and people concerned with radiation protection and the biological effects of low-dose irradiation

  18. Local Control Following Permanent Prostate Brachytherapy: Effect of High Biologically Effective Dose on Biopsy Results and Oncologic Outcomes

    International Nuclear Information System (INIS)

    Purpose: To determine factors that influence local control and systemic relapse in patients undergoing permanent prostate brachytherapy (PPB). Methods and Materials: A total of 584 patients receiving PPB alone or PPB with external beam radiation therapy (19.5%) agreed to undergo prostate biopsy (PB) at 2 years postimplantion and yearly if results were positive or if the prostate-specific antigen (PSA) level increased. Short-term hormone therapy was used with 280 (47.9%) patients. Radiation doses were converted to biologically effective doses (BED) (using α/β = 2). Comparisons were made by chi-square analysis and linear regression. Survival was determined by the Kaplan-Meier method. Results: The median PSA concentration was 7.1 ng/ml, and the median follow-up period was 7.1 years. PB results were positive for 48/584 (8.2%) patients. Positive biopsy results by BED group were as follows: 22/121 (18.2%) patients received a BED of ≤150 Gy; 15/244 (6.1%) patients received >150 to 200 Gy; and 6/193 (3.1%; p 200 Gy. Significant associations of positive PB results by risk group were low-risk group BED (p = 0.019), intermediate-risk group hormone therapy (p = 0.011) and BED (p = 0.040), and high-risk group BED (p = 0.004). Biochemical freedom from failure rate at 7 years was 82.7%. Biochemical freedom from failure rate by PB result was 84.7% for negative results vs. 59.2% for positive results (p 200 Gy with an α/β ratio of 2 yields 96.9% local control rate. Failure to establish local control impacts survival.

  19. The role of nuclear reactions in Monte Carlo calculations of absorbed and biological effective dose distributions in hadron therapy

    CERN Document Server

    Brons, S; Elsässer, T; Ferrari, A; Gadioli, E; Mairani, A; Parodi, K; Sala, P; Scholz, M; Sommerer, F

    2010-01-01

    Monte Carlo codes are rapidly spreading among hadron therapy community due to their sophisticated nuclear/electromagnetic models which allow an improved description of the complex mixed radiation field produced by nuclear reactions in therapeutic irradiation. In this contribution results obtained with the Monte Carlo code FLUKA are presented focusing on the production of secondary fragments in carbon ion interaction with water and on CT-based calculations of absorbed and biological effective dose for typical clinical situations. The results of the simulations are compared with the available experimental data and with the predictions of the GSI analytical treatment planning code TRiP.

  20. 3D-personalized Monte Carlo dosimetry in 90Y-microspheres therapies of primary and secondary hepatic cancers: absorbed dose and biological effective dose considerations

    International Nuclear Information System (INIS)

    Full text of publication follows. Purpose: a 3D-Personalized Monte Carlo Dosimetry (PMCD) was developed for treatment planning in nuclear medicine. The method was applied to Selective Internal Radiation Therapy (SIRT) using 90Y-microspheres for unresectable hepatic cancers. Methods: The PMCD method was evaluated for 20 patients treated for hepatic metastases or hepatocellular carcinoma at the European Hospital Georges Pompidou (Paris). First, regions of interest were outlined on the patient CT images. Using the OEDIPE software, patient-specific voxel phantoms were created. 99mTc-MAA SPECT data were then used to generate 3D-matrices of cumulated activity. Absorbed doses and Biologically Effective Dose (BED) were calculated at the voxel scale using the MCNPX Monte Carlo transport code. Finally, OEDIPE was used to determine the maximum injectable activity (MIA) for tolerance criteria on organs at risk (OARs), i.e. the lungs and non tumoral liver (NTL). Tolerance criteria based on mean absorbed doses, mean BED, Dose-Volume Histograms (DVHs) or BED-Volume Histograms (BVHs) were considered. Those MIAs were compared to the Partition Model with tolerance criteria on mean absorbed doses, which is a conventional method applied in clinical practice. Results: compared to Partition Model recommendations, performing dosimetry using the PMCD method enables to increase the activity prescription while ensuring OARs' radiation protection. Moreover, tolerance criteria based on DVHs allow us to enhance treatment planning efficiency by taking advantage of the parallel characteristic of the liver and the lungs, whose functions are not impaired if the level of irradiation to a fraction of the organ is kept sufficiently low. Finally, multi-cycle treatments based on tolerance criteria on mean BED and BVHs, were considered to go further in the dose optimization, taking into account biological considerations such as cell repair or radiosensitivity. Conclusion: besides its feasibility

  1. Biological indicators for radiation dose assessment

    International Nuclear Information System (INIS)

    After an introductory report on the present level of practical experience in using biological indicator systems to identify and assess doses from radiation exposures, the state of the art in the field of biochemical, cytological and immunological indicators was presented as a basis for discussions in working groups. With reference to the type of radiation - gamma radiation, electrons, neutrons - the question was examined how and to which extent body doses could be evaluated on the basis of results from biological indicator systems. The indicator systems were examined and evaluated in working groups under the aspects of practical use, validity of results and demand of research according to uniform criteria. These were, among others, dose effect relationship, detection limit, reproducibility and specificity, interference factors, stress and reasonable inconvenience of the examined person, earliest possible availability of results and the maximum time needed to identify a biological effect after radiation exposure, as well as the possible maximum number of persons examined from a population group of radiation exposed individuals. The results of the working groups discussions were compiled and summarized in recommendations. (orig./MG)

  2. Low dose/low fluence ionizing radiation-induced biological effects: The role of intercellular communication and oxidative metabolism

    Science.gov (United States)

    Azzam, Edouard

    Mechanistic investigations have been considered critical to understanding the health risks of exposure to ionizing radiation. To gain greater insight in the biological effects of exposure to low dose/low fluence space radiations with different linear energy transfer (LET) properties, we examined short and long-term biological responses to energetic protons and high charge (Z) and high energy (E) ions (HZE particles) in human cells maintained in culture and in targeted and non-targeted tissues of irradiated rodents. Particular focus of the studies has been on mod-ulation of gene expression, proliferative capacity, induction of DNA damage and perturbations in oxidative metabolism. Exposure to mean doses of 1000 MeV/nucleon iron ions, by which a small to moderate proportion of cells in an exposed population is targeted through the nucleus by an HZE particle, induced stressful effects in the irradiated and non-irradiated cells in the population. Direct intercellular communication via gap-junctions was a primary mediator of the propagation of stressful effects from irradiated to non-irradiated cells. Compromised prolif-erative capacity, elevated level of DNA damage and oxidative stress evaluated by measurements of protein carbonylation, lipid peroxidation and activity of metabolic enzymes persisted in the progeny of irradiated and non-irradiated cells. In contrast, progeny of cells exposed to high or low doses from 150-1000 MeV protons retained the ability to form colonies and harbored similar levels of micronuclei, a surrogate form of DNA damage, as control, which correlated with normal reactive oxygen species (ROS) levels. Importantly, a significant increase in the spontaneous neoplastic transformation frequency was observed in progeny of bystander mouse embryo fibroblasts (MEFs) co-cultured with MEFs irradiated with energetic iron ions but not protons. Of particular significance, stressful effects were detected in non-targeted tissues of rats that received partial

  3. Effect of low dose radiation (LDR) on biological activity of NK cell

    International Nuclear Information System (INIS)

    Objective: To study the in vitro and in vivo effect of LDR on the proliferation and killing activity of mouse NK cells with exploitation of the related mechanism of signal transduction. The effect of infused NK cells on inhibiton of oncogenesis and tumor burden regression was also studied. Methods: Mononuclear cells extracted from mouse spleen were treated with immunomagnetic bead for the isolation of CD3-/CD16+, CD56+ cells. After verified with flowcytometry, these NK cells were cultured with mice splenic cells (irradiated with 20Gy 60Co gamma ray) as feeder cells and rhIL-2 as induction factor for 3 rounds (5 days each round). Specimens of cultured NK cells were treated with different doses of radiation (25mGy, 75mGy, 200mGy, 500mGy), the proliferation index (PI) with tumoreidal activity on K562 cells (with 3H-TdR) incorporation was examined at 4h, 24h, 48h, 72h after irradiation respectively. The role of P38MAPK signal pathway in the LDR effect was examined with adding either inhibitor (SB203580) or activator (P79350) of P38MAPK into the culture and measuring the PI, Killing activity (as expression of the related factors IFN-gamma, FasL, perforin) of NK cells thereafter. The in vivo test involved exposing mice to whole body 25mGy irradiation, harvesting splenic NK cells at 4h, 24h, 48h, 72h later respectively and performing the above-described in vitro procedures. Inhibition of oncogenesis was examined in vivo with infusion of cultured NK cells (LDR treated vs LDR non-treated) 10 days after infusion of K562 cells into mice and examination of hepatic/splenic CD13+, S-stage cells and peripheral blood tumor cells in the sacrificed animal another 10 days later. Also, K562 cells were innoculated subcutaneously into mice. After tumor nodule formation (2.0 x 2.0 mm), NK cells (LDR treated vs non-treated) were infused and regression of the tumor nodule with the weight of hepatic tumor mass was noticed in sacrificed animals on d 8 and the survival rate on d 40 recorded

  4. Dose rate and biological effects on hydrobionts within the Chernobyl NPP exclusion zone

    International Nuclear Information System (INIS)

    In 2000-2003 the values of the absorbed dose for hydrobionts from reservoirs within the Chernobyl NPP exclusion zone were found to be in the range from 1.8·10-3 to 3.4 Gy/year. The highest value was found for hydrobionts from lakes within the embankment territory on the left-bank flood plain of the Pripyat River, the lowest - for specimens from the running water objects. The chromosome aberration rate in cells of the snail (Limnea stagnalis L.) embryos from the most contaminated reservoirs reached to 25%. (Authors)

  5. Biologically effective dose and definitive radiation treatment for localized prostate cancer. Treatment gaps do affect the risk of biochemical failure

    International Nuclear Information System (INIS)

    It is not clear if prolongation of definitive external radiation therapy for prostate cancer has an effect on biochemical failure. The aim of this work was to evaluate whether the biologically effective dose (BED), and in particular the duration of radiotherapy, intended as overall treatment time, has an effect on biochemical failure rates and to develop a nomogram useful to predict the 6-year probability of biochemical failure. A total of 670 patients with T1-3 N0 prostate cancer were treated with external beam definitive radiotherapy, to a total dose of 72-79.2 Gy in 40-44 fractions. The computed BED values were treated with restricted cubic splines. Variables were checked for colinearity using Spearman's test. The Kaplan-Meier method was used to calculate freedom from biochemical relapse (FFBR) rates. The Cox regression analysis was used to identify prognostic factors of biochemical relapse in the final most performing model and to create a nomogram. Concordance probability estimate and calibration methods were used to validate the nomogram. Neoadjuvant and concomitant androgen deprivation was administered to 475 patients (70 %). The median follow-up was 80 months (range 20-129 months). Overall, the 6-year FFBR rate was 88.3 %. BED values were associated with higher biochemical failure risk. Age, iPSA, risk category, and days of radiotherapy treatment were independent variables of biochemical failure. A prolongation of RT (lower BED values) is associated with an increased risk of biochemical failure. The nomogram may be helpful in decision making for the individual patient. (orig.)

  6. Biologically effective dose in fractionated molecular radiotherapy—application to treatment of neuroblastoma with 131I-mIBG

    Science.gov (United States)

    Mínguez, Pablo; Gustafsson, Johan; Flux, Glenn; Sjögreen Gleisner, Katarina

    2016-03-01

    In this work, the biologically effective dose (BED) is investigated for fractionated molecular radiotherapy (MRT). A formula for the Lea-Catcheside G-factor is derived which takes the possibility of combinations of sub-lethal damage due to radiation from different administrations of activity into account. In contrast to the previous formula, the new G-factor has an explicit dependence on the time interval between administrations. The BED of tumour and liver is analysed in MRT of neuroblastoma with 131I-mIBG, following a common two-administration protocol with a mass-based activity prescription. A BED analysis is also made for modified schedules, when due to local regulations there is a maximum permitted activity for each administration. Modifications include both the simplistic approach of delivering this maximum permitted activity in each of the two administrations, and also the introduction of additional administrations while maintaining the protocol-prescribed total activity. For the cases studied with additional (i.e. more than two) administrations, BED of tumour and liver decreases at most 12% and 29%, respectively. The decrease in BED of the tumour is however modest compared to the two-administration schedule using the maximum permitted activity, where the decrease compared to the original schedule is 47%.

  7. The radiological consequences of notional accidental releases of radioactivity from fast breeder reactors: sensitivity to the dose-effect relationships adopted for early biological effects

    International Nuclear Information System (INIS)

    This study considered the sensitivity to the dose-response relationships adopted for the estimation of early biological effects from notional accidental releases of radioactivity from fast breeder reactors. Two distinct aspects were considered: the sensitivity of the predicted consequences to variation in the dose-mortality relationships for irradiation of the bone marrow and the lung; and the influence of simple supportive medical treatment in reducing the incidence of early deaths in the exposed population. The numbers of early effects estimated in the initial study were relatively insensitive to variation in the dose-mortality relationships within the bounds proposed. The few exceptions concerned releases of particular nuclide composition, and the variation in the predicted consequences could be around an order of magnitude; the absolute numbers of effects however were in general small when the sensitivity was most pronounced. The reduction in the incidence of early deaths when using simple supportive treatment varied markedly with the nuclide composition of the release. Areas of uncertainty were identified where further research and investigation might most profitably be directed with a view to improving the reliability of the dose-effect relationships adopted and hence of the predicted consequences of the release considered. (author)

  8. 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)

  9. Observations on the biological foundations of dose limits

    International Nuclear Information System (INIS)

    In the present article the author examines a certain number of results of biological observations associated to external irradiations and arrives at following conclusions: For γ-radiation the results show an biological efficiency which is below the value of 10-4 rad-1 and which is equally sensitive to lower rates than the minimal dose. For X-radiation at the maximal dose rate of 30 rad/min the observed dose-effect relations are linear according to the CIPR model. For neutrons recently a revision of the estimations of the expositions of the survivants of the nuclear explosions at Japan was performed. The first published results of this revision lead to a dose-effect relationship of D0.7 and a biological efficiency of low doses which is more important than the results of precedent estimations. (orig.)

  10. Pathogenic effects of low dose irradiation: dose-effect relationships

    International Nuclear Information System (INIS)

    There is no evidence of pathogenic effects in human groups exposed to less than 100 mSv at low dose-rate. The attributed effects are therefore the result of extrapolations from higher doses. The validity of such extrapolations is discussed from the point of view of epidemiology as well as cellular and molecular biology. The Chernobyl accident resulted in large excess of thyroid cancers in children; it also raised the point that some actual sanitary effects among distressed populations might be a direct consequence of low doses. Studies under the control of UN have not confirmed this point identifying no dose-effect relationship and 'severe socio-economic and psychological pressures... poverty, poor diet and living conditions, and lifestyle factors' as the main cause for depressed health. Some hypothesis are considered for explaining the dose-dependence and high prevalence of non-cancer causes of death among human groups exposed to more than 300 mSv. (author)

  11. A comparative study of biological effects on tumor cells between low-dose-rate β-irradiation and high- dose-rate γ-irradiation

    International Nuclear Information System (INIS)

    Objective: To elucidate the radiobiological mechanism underlying cancer treatment with low-dose-rate β-irradiation of 32P, by comparing the cell-killing pattern with high-dose-rate γ-irradiation of 60Co. Methods: HeLa cells were exposed to low-dose-rate β-irradiation of 32P or high-dose-rate γ-irradiation of 60Co. Comparisons were made between these two types of radiations, focusing on the cell-killing patterns evaluated by radiation-induced reproductive cell death( senescence) and necrotic cell death through X-gal senescence staining and tRypan blue exclusion method respectively. Results: The results showed that there were different cell-killing patterns in HeLa cells between 32P radiation at dose-rate of 0.375 cGy/min and that of 60Co at dose-rate of 206 cGy/min at 72 h post irradiation. In exposure to 32P, more HeLa cells were lost due to reproductive cell death than to 60Co. X-gal staining showed that senescent cell ratio in HeLa cells after exposure of 32P was higher than after that of 60Co which caused more necrotic cell death. Conclusions: More reproductive and less necrotic cell death contribute to total cell loss in HeLa cells by radiation of 32P than by 60Co. Understanding the underlying mechanism of radiobiology in different radiations is helpful in radiotherapy of malignant tumor by choosing a more reasonable and effective procedure of treatment. (author)

  12. Biologically effective dose and definitive radiation treatment for localized prostate cancer. Treatment gaps do affect the risk of biochemical failure

    Energy Technology Data Exchange (ETDEWEB)

    Sanpaolo, P.; Barbieri, V. [CROB, Rionero in Vulture (Italy). Radiation Oncology Dept.; Genovesi, D. [' ' G. D' Annunzio Univ., Chieti (Italy). Radiation Oncology Dept.

    2014-08-15

    It is not clear if prolongation of definitive external radiation therapy for prostate cancer has an effect on biochemical failure. The aim of this work was to evaluate whether the biologically effective dose (BED), and in particular the duration of radiotherapy, intended as overall treatment time, has an effect on biochemical failure rates and to develop a nomogram useful to predict the 6-year probability of biochemical failure. A total of 670 patients with T1-3 N0 prostate cancer were treated with external beam definitive radiotherapy, to a total dose of 72-79.2 Gy in 40-44 fractions. The computed BED values were treated with restricted cubic splines. Variables were checked for colinearity using Spearman's test. The Kaplan-Meier method was used to calculate freedom from biochemical relapse (FFBR) rates. The Cox regression analysis was used to identify prognostic factors of biochemical relapse in the final most performing model and to create a nomogram. Concordance probability estimate and calibration methods were used to validate the nomogram. Neoadjuvant and concomitant androgen deprivation was administered to 475 patients (70 %). The median follow-up was 80 months (range 20-129 months). Overall, the 6-year FFBR rate was 88.3 %. BED values were associated with higher biochemical failure risk. Age, iPSA, risk category, and days of radiotherapy treatment were independent variables of biochemical failure. A prolongation of RT (lower BED values) is associated with an increased risk of biochemical failure. The nomogram may be helpful in decision making for the individual patient. (orig.) [German] Es ist nicht geklaert, ob die Verlaengerung einer definitiven Strahlentherapie bei der Behandlung von Prostatakarzinompatienten einen Effekt auf das biochemische Versagen hat. Die vorliegende Studie hat das Ziel zu evaluieren, ob biologisch die effektive Dosis und insbesondere die Gesamtdauer der Behandlung eine Wirkung auf das biochemisches Rezidiv haben koennte. Ferner

  13. Are there dangers in biologic dose reduction strategies?

    Science.gov (United States)

    Chan, Christopher K Y; Holroyd, Christopher R; Mason, Alice; Zarroug, Jalaa; Edwards, Christopher J

    2016-07-01

    Biologic dose reduction strategies, for patients with inflammatory rheumatic diseases, have been assessed in multiple studies to assess outcomes compared to ongoing maintenance dosing. Whilst cessation in established disease usually leads to disease flare, dose tapering approaches for those achieving low disease activity often appear to be successful in the short term. However, tapering can be associated with a higher risk of losing disease control and rates of recapture of disease control using the original biologic dose vary between studies. Over relatively short periods of follow-up, a number of studies have shown no statistical difference in radiographic progression in patients tapering or discontinuing biologics. However, a Cochrane review found that radiographic and functional outcomes may be worse after TNF inhibitor discontinuation, and over long-term disease follow-up flares have been associated with radiographic progression and worse patient reported outcomes. To date, no studies of biological therapy dose reduction have specifically investigated the risk of increased immunogenicity or the effects on cardiovascular risk and other co-morbidities, although these remain important potential risks. In addition, whether there are greater dangers in certain dose reduction approaches such as a reduction in dose at the same frequency or a spacing of doses is not established. PMID:26970488

  14. Biological effects of low doses irradiation on human and animal: observations and experiences performed in France and Kazakhstan between 1995 and 2000

    International Nuclear Information System (INIS)

    All the data suggests that low doses of irradiation at low dose rate affects living organisms. All the negative effects that have been observed on the embrittlement of DNA suggest that it is necessary to better quantify the potential risks to the environment and human beings living in such conditions and that the test of comets could be a useful tool for this purpose.The evidence of this instability should be quantified in an even more specific by finer techniques of cyto-genetics or molecular biology techniques. A modelling of irradiation is necessary as it has been begun to do so on a simpler model (plants). In terms of radiation protection it has been demonstrated in animals and in our observing conditions (long-term consequence of irradiation) that the dose-response curve for the low dose and dose rate is neither linear nor infra linear with or without a threshold, but above type linear which means that very low doses of radiation have comparatively at higher doses, a cytogenetic relatively more important.These results are not directly extrapolated to humans, but the question is entirely valid: monitoring of populations currently living in the contaminated areas or exposed in the workplace. Several teams at the international level are beginning to accumulate data in the same direction. (N.C.)

  15. Clinical investigation of the biological effects of a new combination low-dose oral contraceptive ('Ovostat E').

    Science.gov (United States)

    Tarkkila, T; Hulkko, S; Alapiessa, U; Kauraniemi, T

    1977-01-01

    A low-dose contraceptive containing 1 mg of lynestrenol and .05 mg of ethinyl estradiol was studied over 12 cycles in 11 healthy fertile women volunteers. The subjects were aged 20-30 years. Measurements were taken of urinary luteinizing hormone (LH), pregnanediol, and estrogen, and serum progesterone and estradiol values; in addition, on a fixed schedule during treatment, the 3rd, 5th, 7th, and 12th months, vaginal smears and endometrial biopsies were taken, along with SGOT and SGPT determinations. According to determinations, ovulation was inhibited during every cycle tested. A clear estrogenic effect was evident in the karyopyknotic index, during cycle 3, at the beginning of the cycle which became a progestational effect around Day 13 (biphasic). In cycle 6, the indexes of cytology decreased, but during Cycle 12, they rose a bit again. Basal body temperature during treatment was monophasic. Cervical mucus assessed by spinnbarket during treatment was low and arborization absent. The SGOT and SGPT liver function tests were within normal values in all cycles in 7 women; 4 showed clearly higher levels in Cycles 3 and 12. None of the cycles showed the high midcycle urinary excretion of LH. No significant side effects were reported. Examination of the endometrial biopsies showed a drug effect in all cases and there was no secretory activity in any of the samples. These findings confirm clinical results that show this low-dose combination to be an effective contraceptive agent. PMID:162661

  16. Investigations on construction material and construction concepts in order to obtain dose-reducing effects in the dismantling of the biological shield of a 1300 MWe-PWR

    International Nuclear Information System (INIS)

    Numerical values of neutron fluxes, activations, dose rates etc. as a function of characteristic values of materials required for optimization purposes to reduce the radiation effect of the biological shield of a PWR are not available. Design concepts are presented for biological shields of PWRs made of concrete with respect to both the most suitable application of materials and the design principles aiming at reduced radiation exposure as compared to present designs during entering, waste disposal and ultimate storage. To evaluate the present-state design the above values have been calculated. Suggested alternative designs are biological shields with selective material application, built from precast elements with or without boron carbide layer arranged in front of it. (orig./HP)

  17. A Paradigm Shift in Low Dose Radiation Biology

    Directory of Open Access Journals (Sweden)

    Z. Alatas

    2015-08-01

    Full Text Available When ionizing radiation traverses biological material, some energy depositions occur and ionize directly deoxyribonucleic acid (DNA molecules, the critical target. A classical paradigm in radiobiology is that the deposition of energy in the cell nucleus and the resulting damage to DNA are responsible for the detrimental biological effects of radiation. It is presumed that no radiation effect would be expected in cells that receive no direct radiation exposure through nucleus. The risks of exposure to low dose ionizing radiation are estimated by extrapolating from data obtained after exposure to high dose radiation. However, the validity of using this dose-response model is controversial because evidence accumulated over the past decade has indicated that living organisms, including humans, respond differently to low dose radiation than they do to high dose radiation. Moreover, recent experimental evidences from many laboratories reveal the fact that radiation effects also occur in cells that were not exposed to radiation and in the progeny of irradiated cells at delayed times after radiation exposure where cells do not encounter direct DNA damage. Recently, the classical paradigm in radiobiology has been shifted from the nucleus, specifically the DNA, as the principal target for the biological effects of radiation to cells. The universality of target theory has been challenged by phenomena of radiation-induced genomic instability, bystander effect and adaptive response. The new radiation biology paradigm would cover both targeted and non-targeted effects of ionizing radiation. The mechanisms underlying these responses involve biochemical/molecular signals that respond to targeted and non-targeted events. These results brought in understanding that the biological response to low dose radiation at tissue or organism level is a complex process of integrated response of cellular targets as well as extra-cellular factors. Biological understanding of

  18. Biological dosimetry of ionizing radiation in the high dose range

    International Nuclear Information System (INIS)

    The report reviews briefly methods of dose evaluation after exposure to high doses of ionizing radiation. Validation of two methods also is described: micronucleus (Mn) frequency estimation according Muller and Rode and premature chromosome condensation (PCC) combined with painting of 3 pairs of chromosomes in human lymphocytes. According to Muller and Rode, micronucleus frequency per binucleated cells with at least one Mn linearly increases with dose up to 15 Gy and is suitable end-point for biological dosimetry. These authors, however, examined cells from only one donor. The data reported below were obtained for 5 donors; they point to a considerable individual variation of thus measured response to irradiation. Due to the high degree of inter-donor variability, there is no possibility to apply this approach in biological dosimetry in the dose range 5 - 20 Gy gamma 60Co radiation. A linear response up to 10 Gy was observed only in the case of certain donors. In contrast, determination of the dose-effect relationship with the PCC method gave good results (small inter-individual variation, no plateau effect up to dose 10 Gy), so that with a calibration curve it could be used for dose estimation after exposure to doses up to 10 Gy of X or gamma 60Co radiation. (author)

  19. Biological effect of pulsed dose rate brachytherapy with stepping sources if short half-times of repair are present in tissues

    International Nuclear Information System (INIS)

    Purpose: To explore the possible increase of radiation effect in tissues irradiated by pulsed brachytherapy (PDR) for local tissue dose rates between those 'averaged over the whole pulse' and the instantaneous high dose rates close to the dwell positions. Increased effect is more likely for tissues with short half-times of repair of the order of a few minutes, similar to pulse durations. Methods and Materials: Calculations were done assuming the linear quadratic formula for radiation damage, in which only the dose-squared term is subject to exponential repair. The situation with two components of T(1(2)) is addressed. A constant overall time of 140 h and a constant total dose of 70 Gy were assumed throughout, the continuous low dose rate of 0.5 Gy/h (CLDR) providing the unitary standard effects for each PDR condition. Effects of dose rates ranging from 4 Gy/h to 120 Gy/h (HDR at 2 Gy/min) were studied, covering the gap in an earlier publication. Four schedules were examined: doses per pulse of 0.5, 1, 1.5, and 2 Gy given at repetition frequencies of 1, 2, 3, and 4 h, respectively, each with a range of assumed half-times of repair of 4 min to 1.5 h. Results are presented for late-responding tissues, the differences from CLDR being two or three times greater than for early-responding tissues and most tumors. Results: Curves are presented relating the ratio of increased biological effect (proportional to log cell kill) calculated for PDR relative to CLDR. Ratios as high as 1.5 can be found for large doses per pulse (2 Gy) if the half-time of repair in tissues is as short as a few minutes. The major influences on effect are dose per pulse, half-time of repair in tissue, and--when T(1(2)) is short--the instantaneous dose rate. Maximum ratios of PDR/CLDR occur when the dose rate is such that pulse duration is approximately equal to T(1(2)). As dose rate in the pulse is increased, a plateau of effect is reached, for most T(1(2))s, above 10 to 20 Gy/h, which is therefore

  20. Three dimensional biological dose distribution of antiprotons

    International Nuclear Information System (INIS)

    The goal of external beam cancer therapy is to destroy the tumour while sparing the healthy tissue around it. In hadron therapy, the dose profile of heavy charged particles satisfies this request, because most of the energy is deposited at the end of the particle path, in the Bragg peak. Antiprotons are even more promising, thanks to the extra energy released by annihilation when captured in a normal atom at the end of range. The aim of the AD-4/ACE experiment at CERN is to determine the increase in biological dose near the Bragg peak due to densely ionizing particles emanating from the annihilation of antiprotons. Initial experiments showed the damage to cells inflicted at the end of the beam for identical damage at the skin level to be four times higher for antiprotons than for protons. The radiation field in a spread-out Bragg peak produced with antiprotons is highly mixed and for proper dose planning knowledge of linear energy transfer (LET) and relative biological efficiency (RBE) at any point in the target is needed. We are studying a number of detection methods for their response to mixed radiation fields with the goal to obtain a direct measurement of the 3D LET distribution and report on first results.

  1. Differential tolerance to biological and subjective effects of four closely spaced doses of N,N-dimethyltryptamine in humans.

    Science.gov (United States)

    Strassman, R J; Qualls, C R; Berg, L M

    1996-05-01

    Tolerance of the behavioral effects of the short-acting, endogenous hallucinogen, N,N-dimethyltryptamine (DMT) is seen inconsistently in animals, and has not been produced in humans. The nature and time course of responses to repetitive, closely spaced administrations of an hallucinogenic dose of DMT were characterized. Thirteen experienced hallucinogen users received intravenous 0.3 mg/kg DMT fumarate, or saline placebo, four times, at 30 min intervals, on 2 separate days, in a randomized, double-blind, design. Tolerance to "psychedelic" subjective effects did not occur according to either clinical interview or Hallucinogen Rating Scale scores. Adrenocorticotropic hormone (ACTH), prolactin, cortisol, and heart rate responses decreased with repeated DMT administration, although blood pressure did not. These data demonstrate the unique properties of DMT relative to other hallucinogens and underscore the differential regulation of the multiple processes mediating the effects of DMT. PMID:8731519

  2. Biological effects of radiation

    International Nuclear Information System (INIS)

    This fourth chapter presents: cell structure and metabolism; radiation interaction with biological tissues; steps of the production of biological effect of radiation; radiosensitivity of tissues; classification of biological effects; reversibility, transmissivity and influence factors; pre-natal biological effects; biological effects in therapy and syndrome of acute irradiation

  3. Temporal Lobe Reactions After Carbon Ion Radiation Therapy: Comparison of Relative Biological Effectiveness–Weighted Tolerance Doses Predicted by Local Effect Models I and IV

    International Nuclear Information System (INIS)

    Purpose: To compare the relative biological effectiveness (RBE)–weighted tolerance doses for temporal lobe reactions after carbon ion radiation therapy using 2 different versions of the local effect model (LEM I vs LEM IV) for the same patient collective under identical conditions. Methods and Materials: In a previous study, 59 patients were investigated, of whom 10 experienced temporal lobe reactions (TLR) after carbon ion radiation therapy for low-grade skull-base chordoma and chondrosarcoma at Helmholtzzentrum für Schwerionenforschung (GSI) in Darmstadt, Germany in 2002 and 2003. TLR were detected as visible contrast enhancements on T1-weighted MRI images within a median follow-up time of 2.5 years. Although the derived RBE-weighted temporal lobe doses were based on the clinically applied LEM I, we have now recalculated the RBE-weighted dose distributions using LEM IV and derived dose-response curves with Dmax,V-1 cm³ (the RBE-weighted maximum dose in the remaining temporal lobe volume, excluding the volume of 1 cm³ with the highest dose) as an independent dosimetric variable. The resulting RBE-weighted tolerance doses were compared with those of the previous study to assess the clinical impact of LEM IV relative to LEM I. Results: The dose-response curve of LEM IV is shifted toward higher values compared to that of LEM I. The RBE-weighted tolerance dose for a 5% complication probability (TD5) increases from 68.8 ± 3.3 to 78.3 ± 4.3 Gy (RBE) for LEM IV as compared to LEM I. Conclusions: LEM IV predicts a clinically significant increase of the RBE-weighted tolerance doses for the temporal lobe as compared to the currently applied LEM I. The limited available photon data do not allow a final conclusion as to whether RBE predictions of LEM I or LEM IV better fit better clinical experience in photon therapy. The decision about a future clinical application of LEM IV therefore requires additional analysis of temporal lobe reactions in a comparable

  4. Biological dose estimation for accidental supra-high dose gamma-ray exposure

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Y., E-mail: yingchen29@yahoo.com.cn [Department of Radiation Toxicology and Oncology, Beijing Institute of Radiation Medicine, 27 Taiping Road, Haidian District, Beijing 100850 (China); Yan, X.K. [Department of Radiation Toxicology and Oncology, Beijing Institute of Radiation Medicine, 27 Taiping Road, Haidian District, Beijing 100850 (China); Department of Radiation Safety, Beijing Institute of Nuclear and Chemical Safety, 14 Guan-cun, Dongcheng District, Beijing 100077 (China); Du, J.; Wang, Z.D.; Zhang, X.Q.; Zeng, F.G.; Zhou, P.K. [Department of Radiation Toxicology and Oncology, Beijing Institute of Radiation Medicine, 27 Taiping Road, Haidian District, Beijing 100850 (China)

    2011-09-15

    To correctly estimate the biological dose of victims accidentally exposed to a very high dose of {sup 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 {sup 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{sup -3}D{sup 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 {gamma}-irradiation from a supra-high dose {sup 60}Co gamma-ray accident.

  5. Absorbed dose and biologically effective dose in patients with high-risk non-Hodgkin's lymphoma treated with high-activity myeloablative {sup 90}Y-ibritumomab tiuxetan (Zevalin registered)

    Energy Technology Data Exchange (ETDEWEB)

    Chiesa, C.; Coliva, A.; Maccauro, M.; Seregni, E.; Bombardieri, E. [Foundation IRCCS Istituto Nazionale Tumori, Nuclear Medicine Division, Milan (Italy); Botta, F. [University of Milan, Health Physics Postgraduate School, Milan (Italy); Devizzi, L.; Guidetti, A. [Foundation IRCCS Istituto Nazionale Tumori, ' ' Cristina Gandini' ' Medical Oncology, Milan (Italy); Carlo-Stella, C.; Gianni, M.A. [Foundation IRCCS Istituto Nazionale Tumori, ' ' Cristina Gandini' ' Medical Oncology, Milan (Italy); University of Milan, Medical Oncology, Milan (Italy)

    2009-11-15

    The aim of this study was to carry out two different dose estimation approaches in patients with non-Hodgkin's lymphoma (NHL) treated with a myeloablative amount of {sup 90}Y-labelled ibritumomab tiuxetan (Zevalin registered) in an open-label dose escalation study. Twenty-seven patients with relapsed/refractory or de novo high-risk NHL receiving one myeloablative dose of {sup 90}Y-ibritumomab tiuxetan followed by tandem stem cell reinfusion were evaluated for dose estimate. The injected activity was 30 MBq/kg in 12 patients and 45 MBq/kg in 15 patients. Dose estimation was performed 1 week prior to {sup 90}Y-ibritumomab tiuxetan by injection of {sup 111}In-ibritumomab tiuxetan (median activity: 200 MBq). The absorbed dose (D) and the biologically effective dose (BED) were calculated. The absorbed doses per unit activity (Gy/GBq) were [median (range)]: heart wall 4.6 (2.5-9.7), kidneys 5.1 (2.8-10.5), liver 6.1 (3.9-10.4), lungs 2.9 (1.5-6.8), red marrow 1.0 (0.5-1.7), spleen 7.0 (1.5-14.4) and testes 4.9 (2.9-16.7). The absorbed dose (Gy) for the 15 patients treated with 45 MBq/kg were: heart wall 17.0 (8.7-25.4), kidneys 17.1 (7.9-22.4), liver 20.8 (15.4-28.3), lungs 8.1 (5.4-11.4), red marrow 3.1 (2.0-4.0), spleen 26.2 (17.0-35.6) and testes 17.3 (9.0-28.4). At the highest activities the acute haematological toxicity was mild or moderate and of very short duration, and it was independent of the red marrow absorbed dose. No secondary malignancy or treatment-related myelodysplastic syndrome was observed. No non-haematological toxicity (liver, kidney, lung) was observed during a follow-up period of 24-48 months. The use of 45 MBq/kg of {sup 90}Y-ibritumomab tiuxetan in association with stem cell autografting resulted in patients being free of toxicity in non-haematological organs. These clinical findings were in complete agreement with our dose estimations, considering both organ doses and BED values. (orig.)

  6. A graphical user interface (GUI) toolkit for the calculation of three-dimensional (3D) multi-phase biological effective dose (BED) distributions including statistical analyses.

    Science.gov (United States)

    Kauweloa, Kevin I; Gutierrez, Alonso N; Stathakis, Sotirios; Papanikolaou, Niko; Mavroidis, Panayiotis

    2016-07-01

    A toolkit has been developed for calculating the 3-dimensional biological effective dose (BED) distributions in multi-phase, external beam radiotherapy treatments such as those applied in liver stereotactic body radiation therapy (SBRT) and in multi-prescription treatments. This toolkit also provides a wide range of statistical results related to dose and BED distributions. MATLAB 2010a, version 7.10 was used to create this GUI toolkit. The input data consist of the dose distribution matrices, organ contour coordinates, and treatment planning parameters from the treatment planning system (TPS). The toolkit has the capability of calculating the multi-phase BED distributions using different formulas (denoted as true and approximate). Following the calculations of the BED distributions, the dose and BED distributions can be viewed in different projections (e.g. coronal, sagittal and transverse). The different elements of this toolkit are presented and the important steps for the execution of its calculations are illustrated. The toolkit is applied on brain, head & neck and prostate cancer patients, who received primary and boost phases in order to demonstrate its capability in calculating BED distributions, as well as measuring the inaccuracy and imprecision of the approximate BED distributions. Finally, the clinical situations in which the use of the present toolkit would have a significant clinical impact are indicated. PMID:27265044

  7. Biological dose representation for carbon-ion radiotherapy of unconventional fractionation

    OpenAIRE

    Kanematsu, Nobuyuki; Inaniwa, Taku

    2016-01-01

    In carbon-ion radiotherapy, single-beam delivery each day in alternate directions has been commonly practiced for operational efficiency, taking advantage of the Bragg peak and the relative biological effectiveness (RBE) for uniform dose conformation to a tumor. The treatment plans are usually evaluated with total RBE-weighted dose, which is however deficient in relevance to the biological effect in the linear-quadratic model due to its quadratic-dose term, or the dose-fractionation effect. I...

  8. Effects of low doses

    International Nuclear Information System (INIS)

    Actually, even though it is comfortable for the risk management, the hypothesis of the dose-effect relationship linearity is not confirmed for any model. In particular, in the area of low dose rate delivered by low let emitters. this hypothesis is debated at the light of recent observations, notably these ones relative to the mechanisms leading to genetic instability and induction eventuality of DNA repair. The problem of strong let emitters is still to solve. (N.C.)

  9. Biological effects of neutrons

    International Nuclear Information System (INIS)

    Although the occasion to be exposed to neutrons is rare in our life, except for nuclear accidents like in the critical accident at Tokai-mura in 1999, countermeasures against accident should be always prepared. In the Tokai-mura accident, residents received less than 21 mSv of neutrons and gamma rays. The cancer risks and fetal effects of low doses of neutrons were matters of concern among residents. The purpose of this program is to investigate the relative biological effectiveness (RBE) for leukemias, and thereby to assess risks of neutrons. Animal experiments are planed to obtain the following RBEs: (1) RBE for the induction of leukemias in mice and (2) RBE for effects on fetuses. Cyclotron fast neutrons (10 MeV) and electrostatic accelerator-derived neutrons (2 MeV) are used for exposure in this program. Furthermore, cytological and cytogenetic analyses will be performed. (author)

  10. The effects of Myxobolus cerebralis, myxospore dose on triactinomyxon production and biology of Tubifex tubifex from two geographic regions

    Science.gov (United States)

    Stevens, Richard; Kerans, B.L.; Lemmon, J. C.; Rasmussen, Charlotte

    2001-01-01

    The aquatic oligochaete Tubifex tubifex is an obligate host of Myxobolus cerebralis, the causative agent of salmonid whirling disease. Tubifex tubifex can become infected by ingesting myxospores ofM. cerebralis that have been released into sediments upon death and decomposition of infected salmonids. Infected worms release triactinomyxons into the water column that then infect salmonids. How the dose of myxospores ingested by T. tubifex influences parasite proliferation and the worm host are not well understood. Using replicated laboratory experiments, we examined how differing doses of myxospores (50, 500, 1,000 per worm) influenced triactinomyxon production and biomass, abundance, and individual weight of 2 geographically distinct populations of T. tubifex. Worm populations produced differing numbers of triactinomyxons, but, within a population, the production did not differ among myxospore doses. At the lowest myxospore dose, 1 worm population produced 45 times more triactinomyxons than myxospores received, whereas the other produced only 6 times more triactinomyxons than myxospores. Moreover, total T. tubifex biomass, abundance, and individual weight were lower among worms receiving myxospores than in myxospore-free controls. Thus, T. tubifex populations differ in ability to support the replication of M. cerebralis, and infection has measurable consequences on fitness of the worm host. These results suggest that variability in whirling disease severity observed in wild salmonid populations may partially be attributed to differences in T. tubifex populations.

  11. Biological effect of dose distortion by fiducial markers in spot-scanning proton therapy with a limited number of fields: A simulation study

    International Nuclear Information System (INIS)

    Purpose: In accurate proton spot-scanning therapy, continuous target tracking by fluoroscopic x ray during irradiation is beneficial not only for respiratory moving tumors of lung and liver but also for relatively stationary tumors of prostate. Implanted gold markers have been used with great effect for positioning the target volume by a fluoroscopy, especially for the cases of liver and prostate with the targets surrounded by water-equivalent tissues. However, recent studies have revealed that gold markers can cause a significant underdose in proton therapy. This paper focuses on prostate cancer and explores the possibility that multiple-field irradiation improves the underdose effect by markers on tumor-control probability (TCP). Methods: A Monte Carlo simulation was performed to evaluate the dose distortion effect. A spherical gold marker was placed at several characteristic points in a water phantom. The markers were with two different diameters of 2 and 1.5 mm, both visible on fluoroscopy. Three beam arrangements of single-field uniform dose (SFUD) were examined: one lateral field, two opposite lateral fields, and three fields (two opposite lateral fields + anterior field). The relative biological effectiveness (RBE) was set to 1.1 and a dose of 74 Gy (RBE) was delivered to the target of a typical prostate size in 37 fractions. The ratios of TCP to that without the marker (TCPr) were compared with the parameters of the marker sizes, number of fields, and marker positions. To take into account the dependence of biological parameters in TCP model, α/β values of 1.5, 3, and 10 Gy (RBE) were considered. Results: It was found that the marker of 1.5 mm diameter does not affect the TCPs with all α/β values when two or more fields are used. On the other hand, if the marker diameter is 2 mm, more than two irradiation fields are required to suppress the decrease in TCP from TCPr by less than 3%. This is especially true when multiple (two or three) markers are used

  12. Biological effect of dose distortion by fiducial markers in spot-scanning proton therapy with a limited number of fields: A simulation study

    Energy Technology Data Exchange (ETDEWEB)

    Matsuura, Taeko; Maeda, Kenichiro; Sutherland, Kenneth; Takayanagi, Taisuke; Shimizu, Shinichi; Takao, Seishin; Miyamoto, Naoki; Nihongi, Hideaki; Toramatsu, Chie; Nagamine, Yoshihiko; Fujimoto, Rintaro; Suzuki, Ryusuke; Ishikawa, Masayori; Umegaki, Kikuo; Shirato, Hiroki [Department of Medical Physics, Hokkaido University Graduate School of Medicine, Sapporo, Hokkaido, 060-8638 (Japan); Hitachi, Ltd., Hitachi Research Laboratory, 7-2-1 Omika-cho, Hitachi-shi, Ibaraki 319-1221 (Japan); Department of Radiation Medicine, Hokkaido University Graduate School of Medicine, Sapporo, Hokkaido, 060-8638 (Japan); Department of Medical Physics, Hokkaido University Graduate School of Medicine, Sapporo, Hokkaido, 060-8638 (Japan); Hitachi, Ltd., Hitachi Works, 3-1-1 Saiwai-cho, Hitachi-shi, Ibaraki 317-8511 (Japan); Hitachi, Ltd., Hitachi Research Laboratory, 7-2-1 Omika-cho, Hitachi-shi, Ibaraki 319-1221 (Japan); Department of Medical Physics, Hokkaido University Graduate School of Medicine, Sapporo, Hokkaido, 060-8638 (Japan); Department of Radiation Medicine, Hokkaido University Graduate School of Medicine, Sapporo, Hokkaido, 060-8638 (Japan)

    2012-09-15

    Purpose: In accurate proton spot-scanning therapy, continuous target tracking by fluoroscopic x ray during irradiation is beneficial not only for respiratory moving tumors of lung and liver but also for relatively stationary tumors of prostate. Implanted gold markers have been used with great effect for positioning the target volume by a fluoroscopy, especially for the cases of liver and prostate with the targets surrounded by water-equivalent tissues. However, recent studies have revealed that gold markers can cause a significant underdose in proton therapy. This paper focuses on prostate cancer and explores the possibility that multiple-field irradiation improves the underdose effect by markers on tumor-control probability (TCP). Methods: A Monte Carlo simulation was performed to evaluate the dose distortion effect. A spherical gold marker was placed at several characteristic points in a water phantom. The markers were with two different diameters of 2 and 1.5 mm, both visible on fluoroscopy. Three beam arrangements of single-field uniform dose (SFUD) were examined: one lateral field, two opposite lateral fields, and three fields (two opposite lateral fields + anterior field). The relative biological effectiveness (RBE) was set to 1.1 and a dose of 74 Gy (RBE) was delivered to the target of a typical prostate size in 37 fractions. The ratios of TCP to that without the marker (TCP{sub r}) were compared with the parameters of the marker sizes, number of fields, and marker positions. To take into account the dependence of biological parameters in TCP model, {alpha}/{beta} values of 1.5, 3, and 10 Gy (RBE) were considered. Results: It was found that the marker of 1.5 mm diameter does not affect the TCPs with all {alpha}/{beta} values when two or more fields are used. On the other hand, if the marker diameter is 2 mm, more than two irradiation fields are required to suppress the decrease in TCP from TCP{sub r} by less than 3%. This is especially true when multiple

  13. Studies on the biological effects of chemical defense mechanisms in vivo activated by low-dose irradiation

    International Nuclear Information System (INIS)

    Active oxygens produced by low-dose irradiation can induce the synthesis of proteins involved in the active oxygen reduction path and can activate the chemical self-defense mechanisms in vivo, which can alleviate the injuries caused by active oxygens themselves. The following findings suggests that it is not only by low-dose irradiation that can induce the responses described above but also by any physical and/or chemical stresses which can produce small amount of active oxygens in vivo. 1. X-irradiation with 0.5 Gy and/or water immersion and restraint induced heat shock protein (HSP)70 in rat stomach cells. HSP70 was also induced in adrenal cells by paraquat administration. 2. The SOD activity in pancreas of rat significantly increased by γ-irradiation with 0.5 Gy. 0.5 Gy irradiation preceeding the alloxan administration significantly suppressed the increase in pancreatic lipid peroxides and in blood glucose levels, degranulation in β cells, and decrease in blood insulin levels, respectively. 3. Inhalation of radon, which is a radioactive gaseous element and emits an α particle when it decays, significantly prevented the decrease in insulin levels and increase in glucose levels in blood of rabbit, respectively. (author). 85 refs

  14. Biological effect of fast neutrons

    International Nuclear Information System (INIS)

    The efficiency of fast neutrons of the energy range from 1.7 to 5 MeV in reducing the reticulocyte count and in diminishing the spleen weight was studied in male NMRI mice and compared with the effects of 250 kV X-rays. The neutron induced decrease of reticulocyte number in the peripheral blood is complete two days after irradiation. At this time even low doses cause a maximal effect. The relation between the rise of effect and the increase of exposure is great in the range of low doses and small in high doses. The relative biological effectiveness of neutrons in reducing the reticulocyte count is 2.5 after low doses and 1.2 after high doses. The spleen of irradiated mice shows a marked loss of weight, the lowest weight values are observed at the second day after irradiation. The relative effectiveness of neutrons in diminishing the spleen weight is 2.1 at low doses, the RBE decreases to 1.4 and rises again to 1.9 at higher doses. These results are compared with previous findings on mortality response and leucocyte and lymphocyte decrease in mice after neutron irradiation. Reticulocyte and lymphocyte count are found to be useful indicators for the detection and evaluation of neutron damage in the sublethal dose range. (orig.)

  15. Biological effects of ionizing radiation

    International Nuclear Information System (INIS)

    The efficient dose of ionizing radiation (I.R.), expressed in sievert is a weighting of the deposited energy (absorbed dose in grays) by factors that take into account the radiation hazard and tissues radiosensitivity. it is useful in radiation protection because it allows to add exposures to ionizing radiation of different nature. for low doses, it has no probabilistic value. The determinist effects of ionizing radiation are observed from thresholds of several hundred of milli sievert. The seriousness grows with the dose. The whole-body doses exceeding 8 Sv are always lethal. The radio-induced cancers are observed only for doses exceeding 100 to 200 mSv for adults, delivered at a self important dose rate. Their seriousness does not depend on the dose. Their appear fortuity (stochastic effect) with a various individual susceptibility, genetically determined. The number of eventual radio-induced cancers coming from the exposure of a high number of persons to low dose of ionizing radiation (<100 mSv) cannot be evaluated with a linear without threshold model. these models, however usually used, do not take into account the biological reality of cell defense mechanisms, tissues or whole body defense mechanisms, these one being different against low or high doses of ionizing radiation. Against low doses, the preponderant mechanism is the elimination of potentially dangerous damaged cells. Against high doses, the repair of damaged cells is imperative to preserve the tissue functions. It can lead to DNA repair errors (radio-induced mutations) and canceration. The radio-induced congenital malformations are effects with threshold. The radio-induced carcinogenesis in utero is a stochastic effect. The radio-induced hereditary congenital malformations have never been highlighted for man. (N.C.)

  16. Biological optimization of heterogeneous dose distributions in systemic radiotherapy

    International Nuclear Information System (INIS)

    The standard computational method developed for internal radiation dosimetry is the MIRD (medical internal radiation dose) formalism, based on the assumption that tumor control is given by uniform dose and activity distributions. In modern systemic radiotherapy, however, the need for full 3D dose calculations that take into account the heterogeneous distribution of activity in the patient is now understood. When information on nonuniform distribution of activity becomes available from functional imaging, a more patient specific 3D dosimetry can be performed. Application of radiobiological models can be useful to correlate the calculated heterogeneous dose distributions to the current knowledge on tumor control probability of a homogeneous dose distribution. Our contribution to this field is the introduction of a parameter, the F factor, already used by our group in studying external beam radiotherapy treatments. This parameter allows one to write a simplified expression for tumor control probability (TCP) based on the standard linear quadratic (LQ) model and Poisson statistics. The LQ model was extended to include different treatment regimes involving source decay, incorporating the repair 'μ' of sublethal radiation damage, the relative biological effectiveness and the effective 'waste' of dose delivered when repopulation occurs. The sensitivity of the F factor against radiobiological parameters (α,β,μ) and the influence of the dose volume distribution was evaluated. Some test examples for 131I and 90Y labeled pharmaceuticals are described to further explain the properties of the F factor and its potential applications. To demonstrate dosimetric feasibility and advantages of the proposed F factor formalism in systemic radiotherapy, we have performed a retrospective planning study on selected patient case. F factor formalism helps to assess the total activity to be administered to the patient taking into account the heterogeneity in activity uptake and dose

  17. Study on the inhalation dose estimate and biological effects from thoron and its progeny nuclides using mice

    International Nuclear Information System (INIS)

    The present work is aimed to explore the effect of Thoron inhalation on various tissues of Swiss albino mice. Mice were exposed to thoron inside a fabricated thoron chamber containing thorium oxide and various parameters such as extent of cellular DNA damage, levels of tissue antioxidants, serum parameters, blood count, histopathology on selected tissues, expression of NF-κB in lung tissues, etc were carried out

  18. Study on the inhalation dose estimate and biological effects from thoron and its progeny nuclides using mice

    International Nuclear Information System (INIS)

    The present work is aimed to explore the effect of thoron inhalation on various tissues of Swiss albino mice. Mice were exposed to thoron inside a fabricated thoron chamber containing thorium oxide and various parameters such as extent of cellular DNA damage, levels of tissue antioxidants, serum parameters, blood count, histopathology on selected tissues, expression of NF-ĸB in lung tissues etc were carried out

  19. Use of Concept of Chemotherapy-Equivalent Biologically Effective Dose to Provide Quantitative Evaluation of Contribution of Chemotherapy to Local Tumor Control in Chemoradiotherapy Cervical Cancer Trials

    International Nuclear Information System (INIS)

    Purpose: To express the magnitude of the contribution of chemotherapy to local tumor control in chemoradiotherapy cervical cancer trials in terms of the concept of the biologically effective dose. Methods and Materials: The local control rates of both arms of each study (radiotherapy vs. radiotherapy plus chemotherapy) reported from randomized controlled trials of concurrent chemoradiotherapy for cervical cancer were reviewed and expressed using the Poisson model for tumor control probability (TCP) as TCP = exp(-exp E), where E is the logarithm of cell kill. By combining the two TCP values from each study, we calculated the chemotherapy-related log cell kill as Ec = ln[(lnTCPRadiotherapy)/(lnTCPChemoradiotherapy)]. Assuming a range of radiosensitivities (α = 0.1-0.5 Gy-1) and taking the calculated log cell kill, we calculated the chemotherapy-BED, and using the linear quadratic model, the number of 2-Gy fractions corresponding to each BED. The effect of a range of tumor volumes and radiosensitivities (α Gy-1) on the TCP was also explored. Results: The chemotherapy-equivalent number of 2-Gy fractions range was 0.2-4 and was greater in tumors with lower radiosensitivity. In those tumors with intermediate radiosensitivity (α = 0.3 Gy-1), the equivalent number of 2-Gy fractions was 0.6-1.3, corresponding to 120-260 cGy of extra dose. The opportunities for clinically detectable improvement are only available in tumors with intermediate radiosensitivity with α = 0.22-0.28 Gy-1. The dependence of TCP on the tumor volume decreases as the radiosensitivity increases. Conclusion: The results of our study have shown that the contribution of chemotherapy to the TCP in cervical cancer is expected to be clinically detectable in larger and less-radiosensitive tumors

  20. Which Is the Optimal Biologically Effective Dose of Stereotactic Body Radiotherapy for Stage I Non–Small-Cell Lung Cancer? A Meta-Analysis

    International Nuclear Information System (INIS)

    Purpose: To assess the relationship between biologically effective dose (BED) and efficacy of stereotactic body radiation therapy (SBRT) and to explore the optimal BED range for Stage I non–small-cell lung cancer (NSCLC). Methods and Materials: Eligible studies were identified on Medline, Embase, the Cochrane Library, and the proceedings of annual meetings through June 2010. According to the quartile of included studies, BED was divided into four dose groups: low (146 Gy). To obtain pooled estimates of overall survival (OS), cancer-specific survival (CSS), and local control rate (LCR), data were combined in a random effect model. Pooled estimates were corrected for the percentage of small tumors (<3 cm). Results: Thirty-four observational studies with a total of 2,587 patients were included in the meta-analysis. Corrected pooled estimates of 2- or 3-year OS in the medium BED (76.1%, 63.5%) or the medium to high BED (68.3%, 63.2%) groups were higher than in the low (62.3%, 51.9%) or high groups (55.9%, 49.5%), respectively (p ≤ 0.004). Corrected 3-year CSS in the medium (79.5%), medium to high (80.6%), and high groups (90.0%) were higher than in the low group (70.1%, p = 0.016, 0.018, 0.001, respectively). Conclusion: The OS for the medium or medium to high BED groups were higher than those for the low or high BED group for SBRT in Stage I NSCLC. The medium or medium to high BED (range, 83.2 146 Gy) for SBRT may currently be more beneficial and reasonable in Stage I NSCLC.

  1. Clinical Outcomes of Biological Effective Dose-Based Fractionated Stereotactic Radiation Therapy for Metastatic Brain Tumors From Non-Small Cell Lung Cancer

    Energy Technology Data Exchange (ETDEWEB)

    Matsuyama, Tomohiko, E-mail: matsutomo_llp@yahoo.co.jp [Department of Radiation Oncology, Kumamoto University, Kumamoto (Japan); Kogo, Kasei [Kumamoto Radiosurgery Clinic, Kumamoto (Japan); Oya, Natsuo [Department of Radiation Oncology, Kumamoto University, Kumamoto (Japan)

    2013-03-15

    Purpose: To evaluate the efficacy and toxicity of fractionated stereotactic radiation therapy (FSRT) based on biological effective dose (BED), a novel approach to deliver a fixed BED irrespective of dose fractionation, for brain metastases from non-small cell lung cancer (NSCLC). Methods and Materials: Between March 2005 and March 2009 we treated 299 patients with 1 to 5 lesions from NSCLC (573 total brain metastases) with FSRT using Novalis. The dose fractionation schedules were individually determined to deliver a peripheral BED10 (α/β ratio = 10) of approximately 80 Gy{sub 10}. The median number of fractions was 3 (range, 2-10), the median peripheral BED10 was 83.2 Gy (range, 19.1-89.6 Gy). Patients were followed up with magnetic resonance imaging (MRI) studies performed at 1- to 2-month intervals. The local tumor control rate and overall local progression-free and intracranial relapse-free survival were calculated by the Kaplan-Meier method. Results: Local control rates for all 573 lesions at 6 and 12 months were 96.3% and 94.5%, respectively. By multivariate analysis the tumor diameter was the only factor predictive of the local control rate (P=.001). The median overall survival, local progression-free survival, and intracranial relapse-free survival were 17.1, 14.9, and 4.4 months, respectively. The overall survival, local progression-free survival, and intracranial relapse-free survival rates at 6 and 12 months were 78.5% and 63.3%, 74.3% and 57.8%, and 41.0% and 21.8%, respectively. Six patients (2%) manifested progressive radiation injury to the brain even during therapy with corticosteroids; they underwent hyperbaric oxygen therapy, and follow-up MRI showed improvement. Conclusions: This study showed that BED-based FSRT for brain metastases from NSCLC is a promising strategy that may yield excellent outcomes with acceptable toxicity. Criteria must be established to determine the optimal dose fractionation for individual patients.

  2. Increased Biological Effective Dose of Radiation Correlates with Prolonged Survival of Patients with Limited-Stage Small Cell Lung Cancer: A Systematic Review.

    Directory of Open Access Journals (Sweden)

    Lucheng Zhu

    Full Text Available Thoracic radiotherapy (TRT is a critical component of the treatment of limited-stage small cell lung cancer (LS-SCLC. However, the optimal radiation dose/fractionation remains elusive. This study reviewed current evidence and explored the dose-response relationship in patients with LS-SCLC who were treated with radiochemotherapy.A quantitative analysis was performed through a systematic search of PubMed, Web of Science, and the Cochrane Library. The correlations between the biological effective dose (BED and median overall survival (mOS, median progression-free survival (mPFS, 1-, 3-, and 5-year overall survival (OS as well as local relapse (LR were evaluated.In all, 2389 patients in 19 trials were included in this study. Among these 19 trials, seven were conducted in Europe, eight were conducted in Asia and four were conducted in the United States. The 19 trials that were included consisted of 29 arms with 24 concurrent and 5 sequential TRT arms. For all included studies, the results showed that a higher BED prolonged the mOS (R2 = 0.198, p<0.001 and the mPFS (R2 = 0.045, p<0.001. The results also showed that increased BED improved the 1-, 3-, and 5-year OS. A 10-Gy increment added a 6.3%, a 5.1% and a 3.7% benefit for the 1-, 3-, and 5-year OS, respectively. Additionally, BED was negatively correlated with LR (R2 = 0.09, p<0.001. A subgroup analysis of concurrent TRT showed that a high BED prolonged the mOS (p<0.001 and the mPFS (p<0.001, improved the 1-, 3-, and 5-year OS (p<0.001 and decreased the rate of LR (p<0.001.This study showed that an increased BED was associated with improved OS, PFS and decreased LR in patients with LS-SCLC who were treated with combined chemoradiotherapy, which indicates that the strategy of radiation dose escalation over a limited time frame is worth exploring in a prospective clinical trial.

  3. Clinical Outcomes of Biological Effective Dose-Based Fractionated Stereotactic Radiation Therapy for Metastatic Brain Tumors From Non-Small Cell Lung Cancer

    International Nuclear Information System (INIS)

    Purpose: To evaluate the efficacy and toxicity of fractionated stereotactic radiation therapy (FSRT) based on biological effective dose (BED), a novel approach to deliver a fixed BED irrespective of dose fractionation, for brain metastases from non-small cell lung cancer (NSCLC). Methods and Materials: Between March 2005 and March 2009 we treated 299 patients with 1 to 5 lesions from NSCLC (573 total brain metastases) with FSRT using Novalis. The dose fractionation schedules were individually determined to deliver a peripheral BED10 (α/β ratio = 10) of approximately 80 Gy10. The median number of fractions was 3 (range, 2-10), the median peripheral BED10 was 83.2 Gy (range, 19.1-89.6 Gy). Patients were followed up with magnetic resonance imaging (MRI) studies performed at 1- to 2-month intervals. The local tumor control rate and overall local progression-free and intracranial relapse-free survival were calculated by the Kaplan-Meier method. Results: Local control rates for all 573 lesions at 6 and 12 months were 96.3% and 94.5%, respectively. By multivariate analysis the tumor diameter was the only factor predictive of the local control rate (P=.001). The median overall survival, local progression-free survival, and intracranial relapse-free survival were 17.1, 14.9, and 4.4 months, respectively. The overall survival, local progression-free survival, and intracranial relapse-free survival rates at 6 and 12 months were 78.5% and 63.3%, 74.3% and 57.8%, and 41.0% and 21.8%, respectively. Six patients (2%) manifested progressive radiation injury to the brain even during therapy with corticosteroids; they underwent hyperbaric oxygen therapy, and follow-up MRI showed improvement. Conclusions: This study showed that BED-based FSRT for brain metastases from NSCLC is a promising strategy that may yield excellent outcomes with acceptable toxicity. Criteria must be established to determine the optimal dose fractionation for individual patients

  4. Neutron relative biological effectiveness for solid cancer incidence in the Japanese A-bomb survivors: an analysis considering the degree of independent effects from γ-ray and neutron absorbed doses with hierarchical partitioning.

    Science.gov (United States)

    Walsh, Linda

    2013-03-01

    It has generally been assumed that the neutron and γ-ray absorbed doses in the data from the life span study (LSS) of the Japanese A-bomb survivors are too highly correlated for an independent separation of the all solid cancer risks due to neutrons and due to γ-rays. However, with the release of the most recent data for all solid cancer incidence and the increased statistical power over previous datasets, it is instructive to consider alternatives to the usual approaches. Simple excess relative risk (ERR) models for radiation-induced solid cancer incidence fitted to the LSS epidemiological data have been applied with neutron and γ-ray absorbed doses as separate explanatory covariables. A simple evaluation of the degree of independent effects from γ-ray and neutron absorbed doses on the all solid cancer risk with the hierarchical partitioning (HP) technique is presented here. The degree of multi-collinearity between the γ-ray and neutron absorbed doses has also been considered. The results show that, whereas the partial correlation between the neutron and γ-ray colon absorbed doses may be considered to be high at 0.74, this value is just below the level beyond which remedial action, such as adding the doses together, is usually recommended. The resulting variance inflation factor is 2.2. Applying HP indicates that just under half of the drop in deviance resulting from adding the γ-ray and neutron absorbed doses to the baseline risk model comes from the joint effects of the neutrons and γ-rays-leaving a substantial proportion of this deviance drop accounted for by individual effects of the neutrons and γ-rays. The average ERR/Gy γ-ray absorbed dose and the ERR/Gy neutron absorbed dose that have been obtained here directly for the first time, agree well with previous indirect estimates. The average relative biological effectiveness (RBE) of neutrons relative to γ-rays, calculated directly from fit parameters to the all solid cancer ERR model with both

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

    International Nuclear Information System (INIS)

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

  6. Dose-painting IMRT optimization using biological parameters

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Yusung (Dept. of Radiation Oncology, Univ. of Iowa, Iowa City (United States)); Tome, Wolfgang A. (Dept. of Human Oncology Univ. of Wisconsin, Madison (United States)), E-mail: tome@humonc.wisc.edu

    2010-11-15

    Purpose. Our work on dose-painting based on the possible risk characteristics for local recurrence in tumor subvolumes and the optimization of treatment plans using biological objective functions that are region-specific are reviewed. Materials and methods. A series of intensity modulated dose-painting techniques are compared to their corresponding intensity modulated plans in which the entire PTV is treated to a single dose level, delivering the same equivalent uniform dose (EUD) to the entire PTV. Iso-TCP and iso-NTCP maps are introduced as a tool to aid the planner in the evaluation of the resulting non-uniform dose distributions. Iso-TCP and iso-NTCP maps are akin to iso-dose maps in 3D conformal radiotherapy. The impact of the currently limited diagnostic accuracy of functional imaging on a series of dose-painting techniques is also discussed. Results. Utilizing biological parameters (risk-adaptive optimization) in the generation of dose-painting plans results in an increase in the therapeutic ratio as compared to conventional dose-painting plans in which optimization techniques based on physical dose are employed. Conclusion. Dose-painting employing biological parameters appears to be a promising approach for individualized patient- and disease-specific radiotherapy

  7. Dose-painting IMRT optimization using biological parameters

    International Nuclear Information System (INIS)

    Purpose. Our work on dose-painting based on the possible risk characteristics for local recurrence in tumor subvolumes and the optimization of treatment plans using biological objective functions that are region-specific are reviewed. Materials and methods. A series of intensity modulated dose-painting techniques are compared to their corresponding intensity modulated plans in which the entire PTV is treated to a single dose level, delivering the same equivalent uniform dose (EUD) to the entire PTV. Iso-TCP and iso-NTCP maps are introduced as a tool to aid the planner in the evaluation of the resulting non-uniform dose distributions. Iso-TCP and iso-NTCP maps are akin to iso-dose maps in 3D conformal radiotherapy. The impact of the currently limited diagnostic accuracy of functional imaging on a series of dose-painting techniques is also discussed. Results. Utilizing biological parameters (risk-adaptive optimization) in the generation of dose-painting plans results in an increase in the therapeutic ratio as compared to conventional dose-painting plans in which optimization techniques based on physical dose are employed. Conclusion. Dose-painting employing biological parameters appears to be a promising approach for individualized patient- and disease-specific radiotherapy

  8. Biological dose assessment of 15 victims in Haerbin radiation accident

    International Nuclear Information System (INIS)

    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)

  9. Biological effects of inhaled radionuclides

    International Nuclear Information System (INIS)

    This report focuses on various types of radionuclides that may be inhaled and deposited in the respiratory tract. One of the primary goals of this ICRP Task Group is to assess specifically the biological implications of inhaled plutonium. Because other transuranics are becoming more abundant, information on americium, curium and einsteinium is included. Data are also included from studies of polonium and of several beta-gamma emitting isotopes. The Task Group evaluated most of the data on the biological effects of inhaled radionuclides in experimental animals to identify the tissues at risk and to assess possible dose-response relationships. Few data from human cases of inhaled radionuclides are available for this assessment. The biological effects of nonradioactive air pollutants were also considered to provide the perspective that all air pollutants can have a deleterious effect on human life and to emphasize the possibility for combined or synergistic effects of nonradioactive and radioactive substances on the respiratory tract. (orig./HP)

  10. Comparison of Dosimetric and Biologic Effective Dose Parameters for Prostate and Urethra Using 131Cs and 125I for Prostate Permanent Implant Brachytherapy

    International Nuclear Information System (INIS)

    Purpose: To compare the urethral and prostate absolute and biologic effective doses (BEDs) for 131Cs and 125I prostate permanent implant brachytherapy (PPI). Methods and Materials: Eight previously implanted manually planned 125I PPI patients were replanned manually with 131Cs, and re-planned using Inverse Planning Simulated Annealing. 131Cs activity and the prescribed dose (115 Gy) were determined from that recommended by IsoRay. The BED was calculated for the prostate and urethra using an α/β ratio of 2 and was also calculated for the prostate using an α/β ratio of 6 and a urethral α/β ratio of 2. The primary endpoints of this study were the prostate D90 BED (pD90BED) and urethral D30 BED normalized to the maximal potential prostate D90 BED (nuD30BED). Results: The manual plan comparison (α/β = 2) yielded no significant difference in the prostate D90 BED (median, 192 Gy2 for both isotopes). No significant difference was observed for the nuD30BED (median, 199 Gy2 and 202 Gy2 for 125I and 131Cs, respectively). For the inverse planning simulated annealing plan comparisons (α/β 2), the prostate D90 BED was significantly lower with 131Cs than with 125I (median, 177 Gy2 vs. 187 Gy2, respectively; p = 0.01). However, the nuD30BED was significantly greater with 131Cs than with 125I (median, 192 Gy2 vs. 189 Gy2, respectively; p = 0.01). Both the manual and the inverse planning simulated annealing plans resulted in a significantly lower prostate D90 BED (p = 0.01) and significantly greater nuD30BED for 131Cs (p = 0.01), compared with 125I, when the prostate α/β ratio was 6 and the urethral α/β ratio was 2. Conclusion: This report highlights the controversy in comparing the dose to both the prostate and the organs at risk with different radionuclides

  11. Cytogenetic biological dosimetry. Dose estimative in accidental exposure

    International Nuclear Information System (INIS)

    The methodology of cytogenetic biological dosimetry is studied. The application in estimation of dose in five cases of accidental exposure is reported. An hematological study and culture of lymphocytes is presented. (M.A.C.)

  12. Strategies for Biologic Image-Guided Dose Escalation: A Review

    International Nuclear Information System (INIS)

    There is increasing interest in how to incorporate functional and molecular information obtained by noninvasive, three-dimensional tumor imaging into radiotherapy. The key issues are to identify radioresistant regions that can be targeted for dose escalation, and to develop radiation dose prescription and delivery strategies providing optimal treatment for the individual patient. In the present work, we review the proposed strategies for biologic image-guided dose escalation with intensity-modulated radiation therapy. Biologic imaging modalities and the derived images are discussed, as are methods for target volume delineation. Different dose escalation strategies and techniques for treatment delivery and treatment plan evaluation are also addressed. Furthermore, we consider the need for response monitoring during treatment. We conclude with a summary of the current status of biologic image-based dose escalation and of areas where further work is needed for this strategy to become incorporated into clinical practice

  13. PET imaging for the quantification of biologically heterogeneous tumours: measuring the effect of relative position on image-based quantification of dose-painting targets

    Science.gov (United States)

    McCall, Keisha C; Barbee, David L; Kissick, Michael W; Jeraj, Robert

    2010-01-01

    Quantitative imaging of tumours represents the foundation of customized therapies and adaptive patient care. As such, we have investigated the effect of patient positioning errors on the reproducibility of images of biologically heterogeneous tumours generated by a clinical PET/CT system. A commercial multi-slice PET/CT system was used to acquire 2D and 3D PET images of a phantom containing multiple spheres of known volumes and known radioactivity concentrations and suspended in an aqueous medium. The spheres served as surrogates for sub-tumour regions of biological heterogeneities with dimensions of 5–15 mm. Between image acquisitions, a motorized-arm was used to reposition the spheres in 1 mm intervals along either the radial or the axial direction. Images of the phantom were reconstructed using typical diagnostic reconstruction techniques, and these images were analysed to characterize and model the position-dependent changes in contrast recovery. A simulation study was also conducted to investigate the effect of patient position on the reproducibility of PET imaging of biologically heterogeneous head and neck (HN) tumours. For this simulation study, we calculated the changes in image intensity values that would occur with changes in the relative position of the patients at the time of imaging. PET images of two HN patients were used to simulate an imaging study that incorporated set-up errors that are typical for HN patients. One thousand randomized positioning errors were investigated for each patient. As a result of the phantom study, a position-dependent trend was identified for measurements of contrast recovery of small objects. The peak contrast recovery occurred at radial and axial positions that coincide with the centre of the image voxel. Conversely, the minimum contrast recovery occurred when the object was positioned at the edges of the image voxel. Changing the position of high contrast spheres by one-half the voxel dimension lead to errors in the

  14. PET imaging for the quantification of biologically heterogeneous tumours: measuring the effect of relative position on image-based quantification of dose-painting targets

    Energy Technology Data Exchange (ETDEWEB)

    McCall, Keisha C; Barbee, David L; Kissick, Michael W; Jeraj, Robert [Department of Medical Physics, University of Wisconsin, 1111 Highland Ave, Madison, WI 53705 (United States)

    2010-05-21

    Quantitative imaging of tumours represents the foundation of customized therapies and adaptive patient care. As such, we have investigated the effect of patient positioning errors on the reproducibility of images of biologically heterogeneous tumours generated by a clinical PET/CT system. A commercial multi-slice PET/CT system was used to acquire 2D and 3D PET images of a phantom containing multiple spheres of known volumes and known radioactivity concentrations and suspended in an aqueous medium. The spheres served as surrogates for sub-tumour regions of biological heterogeneities with dimensions of 5-15 mm. Between image acquisitions, a motorized-arm was used to reposition the spheres in 1 mm intervals along either the radial or the axial direction. Images of the phantom were reconstructed using typical diagnostic reconstruction techniques, and these images were analysed to characterize and model the position-dependent changes in contrast recovery. A simulation study was also conducted to investigate the effect of patient position on the reproducibility of PET imaging of biologically heterogeneous head and neck (HN) tumours. For this simulation study, we calculated the changes in image intensity values that would occur with changes in the relative position of the patients at the time of imaging. PET images of two HN patients were used to simulate an imaging study that incorporated set-up errors that are typical for HN patients. One thousand randomized positioning errors were investigated for each patient. As a result of the phantom study, a position-dependent trend was identified for measurements of contrast recovery of small objects. The peak contrast recovery occurred at radial and axial positions that coincide with the centre of the image voxel. Conversely, the minimum contrast recovery occurred when the object was positioned at the edges of the image voxel. Changing the position of high contrast spheres by one-half the voxel dimension lead to errors in the

  15. Biological effects of ionizing radiation

    International Nuclear Information System (INIS)

    It has been emphasised the importance of DNA as the main target for ionizing radiation, that can induce damage by its direct action on this molecule or by an indirect effect mediated by free-radicals generated by water radiolysis. Biological effects of ionizing radiation are influenced not only by the dose but also by the dose-rate and the radiation quality. Radiation induced damage, mainly DNA single and double strand breaks, is detected by molecular sensors which in turn trigger signalling cascades leading to cell cycle arrest to allow DNA repair or programmed cell death (apoptosis). Those effects related with cell death, named deterministic, exhibits a dose-threshold below which they are not observed. Acute radiation syndrome and radiological burns are examples of this kind of effects. Other radiation induced effects, called stochastic, are the consequence of cell transformation and do not exhibit a dose-threshold. This is the case of cancer induction and hereditary effects. The aim of this presentation is briefly describe the main aspects of deterministic and stochastic effects from the point of view of radiobiology and radio pathology. (author)

  16. Isoeffective dose: a concept for biological weighting of absorbed dose in proton and heavier-ion therapies

    CERN Document Server

    Wambersie, A; Menzel, H G; Gahbauer, R; DeLuca, P M; Hendry, J H; Jones, D T L

    2011-01-01

    When reporting radiation therapy procedures, International Commission on Radiation Units and Measurements (ICRU) recommends specifying absorbed dose at/in all clinically relevant points and/or volumes. In addition, treatment conditions should be reported as completely as possible in order to allow full understanding and interpretation of the treatment prescription. However, the clinical outcome does not only depend on absorbed dose but also on a number of other factors such as dose per fraction, overall treatment time and radiation quality radiation biology effectiveness (RBE). Therefore, weighting factors have to be applied when different types of treatments are to be compared or to be combined. This had led to the concept of `isoeffective absorbed dose', introduced by ICRU and International Atomic Energy Agency (IAEA). The isoeffective dose D(IsoE) is the dose of a treatment carried out under reference conditions producing the same clinical effects on the target volume as those of the actual treatment. It i...

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

    Directory of Open Access Journals (Sweden)

    Zhongmin Wang

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

  18. A Systems Biology Approach in Therapeutic Response Study for Different Dosing Regimens—a Modeling Study of Drug Effects on Tumor Growth using Hybrid Systems

    OpenAIRE

    Xiangfang Li; Lijun Qian; Bittner, Michale L.; Dougherty, Edward R.

    2012-01-01

    Motivated by the frustration of translation of research advances in the molecular and cellular biology of cancer into treatment, this study calls for cross-disciplinary efforts and proposes a methodology of incorporating drug pharmacology information into drug therapeutic response modeling using a computational systems biology approach. The objectives are two fold. The first one is to involve effective mathematical modeling in the drug development stage to incorporate preclinical and clinical...

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

    Science.gov (United States)

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

    2016-03-01

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

  20. Biological radiation effects and radioprotection standards

    International Nuclear Information System (INIS)

    In this report, after recalling the mode of action of ionizing radiations, the notions of dose, dose equivalents and the values of natural irradiation, the author describes the biological radiation effects. Then he presents the ICRP recommendations and their applications to the french radioprotection system

  1. Biological effectiveness of fission neutrons

    International Nuclear Information System (INIS)

    Human peripheral blood lymphocytes were exposed to the uranium fission neutrons with different energy spectra, and the effects of changing pattern of energy spectrum on the relative biological effectiveness (RBE) were studied by analyzing dose-response relationship of chromosome aberrations. When the contribution of contaminated gamma-rays was subtracted, the efficiency of chromosomal response to the neutron dose was found to be refractory to the difference in the energy spectrum while the mean energy ranged from 2 MeV to 27 keV. This chromosomal refractoriness to energy spectrum may be explained by the similarity of energy spectrum for kerma contribution; most of the doses being given by neutrons with energy above 50 keV. Small doses given by short tracks may be less efficient. A comparison of these observations with chromosome aberration frequencies in lymphocytes of A-bomb survivors leads to somewhat higher estimate of neutron dose in Hiroshima than the estimate by the recently revised dosimetry system, DS86. (author)

  2. Molecular circuits, biological switches, and nonlinear dose-response relationships.

    OpenAIRE

    Andersen, Melvin E.; Yang, Raymond S.H.; French, C. Tenley; Chubb, Laura S; Dennison, James E

    2002-01-01

    Signaling motifs (nuclear transcriptional receptors, kinase/phosphatase cascades, G-coupled protein receptors, etc.) have composite dose-response behaviors in relation to concentrations of protein receptors and endogenous signaling molecules. "Molecular circuits" include the biological components and their interactions that comprise the workings of these signaling motifs. Many of these molecular circuits have nonlinear dose-response behaviors for endogenous ligands and for exogenous toxicants...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2006-07-01

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

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

    International Nuclear Information System (INIS)

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

  5. Biological indicators for radiation absorbed dose: a review

    International Nuclear Information System (INIS)

    Biological dosimetry has an important role to play in assessing the cumulative radiation exposure of persons working with radiation and also in estimating the true dose received during accidents involving external and internal exposure. Various biodosimetric methods have been tried to estimate radiation dose for the above purposes. Biodosimetric methods include cytogenetic, immunological and mutational assays. Each technique has certain advantages and disadvantages. We present here a review of each technique, the actual method used for detection of dose, the sensitivity of detection and its use in long term studies. (author)

  6. Methemoglobin-Based Biological Dose Assessment for Human Blood.

    Science.gov (United States)

    Zhang, Xiao-Hong; Hu, Xiao-Dan; Zhao, Su-Ying; Xie, Li-Hua; Miao, Yu-Ji; Li, Qun; Min, Rui; Liu, Pei-Dang; Zhang, Hai-Qian

    2016-07-01

    Methemoglobin is an oxidative form of hemoglobin in erythrocytes. The authors' aim was to develop a new biological dosimeter based on a methemoglobin assay. Methemoglobin in peripheral blood (of females or males) that was exposed to a Co source (0.20 Gy min) was quantified using an enzyme-linked immunosorbent assay. The dose range was 0.5-8.0 Gy. In a time-course experiment, the time points 0, 0.02, 1, 2, 3, 7, 15, 21, and 30 d after 4-Gy irradiation of heparinized peripheral blood were used. Methemoglobin levels in a lysed erythrocyte pellet from the irradiated blood of females and males increased with the increasing dose. Methemoglobin levels in female blood irradiated with γ-doses more than 4 Gy were significantly higher than those in male samples at the same doses. Two dose-response relations were fitted to the straight line: one is with the correlation coefficient of 0.98 for females, and the other is with the correlation coefficient of 0.99 for males. The lower limit of dose assessment based on methemoglobin is about 1 Gy. Methemoglobin levels in blood as a result of auto-oxidation increase after 7-d storage at -20 °C. The upregulation of methemoglobin induced by γ-radiation persists for ∼3 d. The absorbed doses that were estimated using the two dose-response relations were close to the actual doses. The results suggest that methemoglobin can be used as a rapid and accurate biological dosimeter for early assessment of absorbed γ-dose in human blood. PMID:27218292

  7. The origins of radiotherapy: Discovery of biological effects of X-rays by Freund in 1897, Kienböck’s crucial experiments in 1900, and still it is the dose

    International Nuclear Information System (INIS)

    The discovery of X-rays by Wilhelm Conrad Röntgen (1845–1923) was triggered by pursuing an anomalous phenomenon: arousal of fluorescence at a distance from tubes in which cathode rays were elicited, a phenomenon which suggested the existence of a new kind of ray other than cathode rays. The discovery of biological effects of these X-rays by Leopold Freund (1868–1943) was triggered by pursuit of the purportedly useless phenomenon of epilation and dermatitis ensuing from X-ray-diagnostic experiments that others had reported. The crucial experiments performed by Robert Kienböck (1871–1953) entailed the proof that X-ray-dose, not electric phenomena, was the active agent of biological effects ensuing when illuminating the skin using Röntgen tubes. For both the discovery of X-rays and the discovery of their biological effectiveness, priority did not matter, but understanding the physical and medico-biological significance of phenomena that others had ignored as a nuisance. Present discussions about the clinical relevance of improving the dose distribution including protons and other charged particles resemble those around 1900 to a certain degree

  8. Biological dosimetry: chromosomal aberration analysis for dose assessment

    International Nuclear Information System (INIS)

    In view of the growing importance of chromosomal aberration analysis as a biological dosimeter, the present report provides a concise summary of the scientific background of the subject and a comprehensive source of information at the technical level. After a review of the basic principles of radiation dosimetry and radiation biology basic information on the biology of lymphocytes, the structure of chromosomes and the classification of chromosomal aberrations are presented. This is followed by a presentation of techniques for collecting blood, storing, transporting, culturing, making chromosomal preparations and scaring of aberrations. The physical and statistical parameters involved in dose assessment are discussed and examples of actual dose assessments taken from the scientific literature are given

  9. Radiation induced damage to the cells of pig hairs: a biological indicator of radiation dose and dose distribution in skin

    International Nuclear Information System (INIS)

    Radiation damage to the matrix cells of actively growing pig hairs resulted in a transient reduction in diameter. This was clearly dose dependent for doses in the range 0.5-5 Gy for 250 kV X rays and 3-8 Gy surface dose for 90Sr β rays. While the relationship between the percentage reduction in hair diameter and the X ray dose was linear between 0.5 and 5 Gy, the skin surface dose for β rays and the percentage reduction in hair diameter was found to be best fitted by a quadratic equation. Differences in the effect produced by X and β ray irradiation can be attributed to the absorption of β rays with depth in the dermis and a correction for this has been applied. This system would appear to have considerable potential for use as a biological dosemeter. (author)

  10. The maximum tolerated dose and biologic effects of 3-aminopyridine-2-carboxaldehyde thiosemicarbazone (3-AP) in combination with irinotecan for patients with refractory solid tumors

    Science.gov (United States)

    Choi, Brian S.; Alberti, Dona B.; Schelman, William R.; Kolesar, Jill M.; Thomas, James P.; Marnocha, Rebecca; Eickhoff, Jens C.; Ivy, S. Percy; Wilding, George; Holen, Kyle D.

    2010-01-01

    Purpose 3-AP is a ribonucleotide reductase inhibitor and has been postulated to act synergistically with other chemotherapeutic agents. This study was conducted to determine the toxicity and antitumor activity of 3-AP with irinotecan. Correlative studies included pharmacokinetics and the effects of ABCB1 and UGT1A1 polymorphisms. Methods The treatment plan consisted of irinotecan on day 1 with 3-AP on days 1-3 of a 21-day cycle. Starting dose was irinotecan 150 mg/m2 and 3-AP 85 mg/m2/d. Polymorphisms of ABCB1 were evaluated by pyrosequencing. Drug concentrations were determined by HPLC. Results Twenty-three patients were enrolled, 10 men and 13 women. Tumor types included 7 patients with pancreatic cancer, 4 with lung cancer, 2 with cholangiocarcinoma, 2 with mesothelioma, 2 with ovarian cancer, and 6 with other malignancies. Two patients experienced dose-limiting toxicity (DLT) at dose level 1, requiring amendment of the dose escalation scheme. Maximal tolerated dose (MTD) was determined to be 3-AP 60 mg/m2/d and irinotecan 200 mg/m2. DLTs consisted of hypoxia, leukopenia, fatigue, infection, thrombocytopenia, dehydration and ALT elevation. One partial response in a patient with refractory non-small cell lung cancer was seen. Genotyping suggests that patients with wild-type ABCB1 have a higher rate of grade 3 or 4 toxicity than those with ABCB1 mutations. Conclusions The MTD for this combination was 3-AP 60 mg/m2/d on days 1-3 and irinotecan 200 mg/m2 on day 1 every 21 days. Antitumor activity in a patient with refractory non-small cell lung cancer was noted at level 1. PMID:20127092

  11. Effective doses in paediatric radiology

    International Nuclear Information System (INIS)

    Because of their longer life expectancy, the risk of late manifestations of detrimental radiation effects is greater in children than in adults and, consequently, paediatric radiology gives ground for more concern regarding radiation protection than radiology of adults. The purpose of our study is to assess in terms of effective doses the magnitude of paediatric patient exposure during conventional X-ray examinations, selected for their high frequency or their relatively high doses to the patient. Effective doses have been derived from measurements of dose-area product (DAP) carried out on over 900 patients undergoing X-ray examinations, in five paediatric units. The conversion coefficients for estimating effective doses are those calculated by the NRPB using Monte-Carlo technique on a series of 5 mathematical phantoms representing 0, 1, 5, 10 and 15 year old children. The annual frequency of X-ray examinations necessary for collective dose calculation are those reported in our last national study on medical exposure, conducted in 1995. The annual effective doses from all medical examinations for the average paediatric patient are as follows: 1.05 mSv for 0 year old, 0.98 mSv for 1 year old, 0.53 mSv for 5 year old, 0.65 mSv for 10 year old and 0.70 mSv for 15 year old. The resulting annual collective effective dose was evaluated at 625 man Sv with the largest contribution of pelvis and hip examinations (34%). The annual collective effective associated with paediatric radiology in Romania represent 5% of the annual value resulting from all diagnostic radiology. Examination of the chest is by far the most frequent procedure for children, accounting for about 60 per cent of all annually performed X-ray conventional examinations. Knowledge of real level of patient dose is an essential component of quality assurance programs in paediatric radiology. (authors)

  12. Therapeutic effects of low radiation doses

    International Nuclear Information System (INIS)

    This editorial explores the scientific basis of radiotherapy with doses of < 1 Gy for various non-malignant conditions, in particular dose-effect relationships, risk-benefit considerations and biological mechanisms. A review of the literature, particularly clinical and experimental reports published more than 50 years ago was conducted to clarify the following problems. 1. The dose-response relationships for the therapeutic effects on three groups of conditions: non-malignant skin disease, arthrosis and other painful degenerative joint disorders and anti-inflammatory radiotherapy; 2. risks after radiotherapy and after the best alternative treatments; 3. the biological mechanisms of the different therapeutic effects. Radiotherapy is very effective in all three groups of disease. Few dose-finding studies have been performed, all demonstrating that the optimal doses are considerable lower than the generally recommended doses, yet few of these studies meet the required standard. In different conditions, risk-benefit analysis of radiotherapy versus the best alternative treatment yields very different results: whereas radiotherapy for acute postpartum mastitis may not be justified any more, the risk-benefit ratio of radiotherapy of other conditions and particularly so in dermatology and some anti-inflammatory radiotherapy appears to be more favourable than the risk-benefit ratio of the best alternative treatments. Radiotherapy can be very effective treatment for various non-malignant conditions such as eczema, psoriasis, periarthritis humeroscapularis, epicondylitis, knee arthrosis, hydradenitis, parotitis and panaritium and probably be associated with less acute and long-term side effects than similarly effective other treatments. Randomized clinical studies are required to find the optimal dosage which, at present, may be unnecessarily high. Since no adequate experimental studies have been performed nothing is known about the mechanisms of these therapeutic radiation

  13. Biological Effects of Ionizing Radiation

    Science.gov (United States)

    Ingram, M.; Mason, W. B.; Whipple, G. H.; Howland, J. W.

    1952-04-07

    This report presents a review of present knowledge and concepts of the biological effects of ionizing radiations. Among the topics discussed are the physical and chemical effects of ionizing radiation on biological systems, morphological and physiological changes observed in biological systems subjected to ionizing radiations, physiological changes in the intact animal, latent changes following exposure of biological systems to ionizing radiations, factors influencing the biological response to ionizing radiation, relative effects of various ionizing radiations, and biological dosimetry.

  14. Therapeutic effects of low radiation doses

    Energy Technology Data Exchange (ETDEWEB)

    Trott, K.R. (Dept. of Radiation Biology, St. Bartholomew' s Medical College, London (United Kingdom))

    1994-01-01

    This editorial explores the scientific basis of radiotherapy with doses of < 1 Gy for various non-malignant conditions, in particular dose-effect relationships, risk-benefit considerations and biological mechanisms. A review of the literature, particularly clinical and experimental reports published more than 50 years ago was conducted to clarify the following problems. 1. The dose-response relationships for the therapeutic effects on three groups of conditions: non-malignant skin disease, arthrosis and other painful degenerative joint disorders and anti-inflammatory radiotherapy; 2. risks after radiotherapy and after the best alternative treatments; 3. the biological mechanisms of the different therapeutic effects. Radiotherapy is very effective in all three groups of disease. Few dose-finding studies have been performed, all demonstrating that the optimal doses are considerable lower than the generally recommended doses. In different conditions, risk-benefit analysis of radiotherapy versus the best alternative treatment yields very different results: whereas radiotherapy for acute postpartum mastitis may not be justified any more, the risk-benefit ratio of radiotherapy of other conditions and particularly so in dermatology and some anti-inflammatory radiotherapy appears to be more favourable than the risk-benefit ratio of the best alternative treatments. Radiotherapy can be very effective treatment for various non-malignant conditions such as eczema, psoriasis, periarthritis humeroscapularis, epicondylitis, knee arthrosis, hydradenitis, parotitis and panaritium and probably be associated with less acute and long-term side effects than similarly effective other treatments. Randomized clinical studies are required to find the optimal dosage which, at present, may be unnecessarily high.

  15. Modelling the Influence of Shielding on Physical and Biological Organ Doses

    CERN Document Server

    Ballarini, Francesca; Ferrari, Alfredo; Ottolenghi, Andrea; Pelliccioni, Maurizio; Scannicchio, Domenico

    2002-01-01

    Distributions of "physical" and "biological" dose in different organs were calculated by coupling the FLUKA MC transport code with a geometrical human phantom inserted into a shielding box of variable shape, thickness and material. While the expression "physical dose" refers to the amount of deposited energy per unit mass (in Gy), "biological dose" was modelled with "Complex Lesions" (CL), clustered DNA strand breaks calculated in a previous work based on "event-by-event" track-structure simulations. The yields of complex lesions per cell and per unit dose were calculated for different radiation types and energies, and integrated into a version of FLUKA modified for this purpose, allowing us to estimate the effects of mixed fields. As an initial test simulation, the phantom was inserted into an aluminium parallelepiped and was isotropically irradiated with 500 MeV protons. Dose distributions were calculated for different values of the shielding thickness. The results were found to be organ-dependent. In most ...

  16. Quantum Effects in Biology

    Science.gov (United States)

    Mohseni, Masoud; Omar, Yasser; Engel, Gregory S.; Plenio, Martin B.

    2014-08-01

    List of contributors; Preface; Part I. Introduction: 1. Quantum biology: introduction Graham R. Fleming and Gregory D. Scholes; 2. Open quantum system approaches to biological systems Alireza Shabani, Masoud Mohseni, Seogjoo Jang, Akihito Ishizaki, Martin Plenio, Patrick Rebentrost, Alàn Aspuru-Guzik, Jianshu Cao, Seth Lloyd and Robert Silbey; 3. Generalized Förster resonance energy transfer Seogjoo Jang, Hoda Hossein-Nejad and Gregory D. Scholes; 4. Multidimensional electronic spectroscopy Tomáš Mančal; Part II. Quantum Effects in Bacterial Photosynthetic Energy Transfer: 5. Structure, function, and quantum dynamics of pigment protein complexes Ioan Kosztin and Klaus Schulten; 6. Direct observation of quantum coherence Gregory S. Engel; 7. Environment-assisted quantum transport Masoud Mohseni, Alàn Aspuru-Guzik, Patrick Rebentrost, Alireza Shabani, Seth Lloyd, Susana F. Huelga and Martin B. Plenio; Part III. Quantum Effects in Higher Organisms and Applications: 8. Excitation energy transfer in higher plants Elisabet Romero, Vladimir I. Novoderezhkin and Rienk van Grondelle; 9. Electron transfer in proteins Spiros S. Skourtis; 10. A chemical compass for bird navigation Ilia A. Solov'yov, Thorsten Ritz, Klaus Schulten and Peter J. Hore; 11. Quantum biology of retinal Klaus Schulten and Shigehiko Hayashi; 12. Quantum vibrational effects on sense of smell A. M. Stoneham, L. Turin, J. C. Brookes and A. P. Horsfield; 13. A perspective on possible manifestations of entanglement in biological systems Hans J. Briegel and Sandu Popescu; 14. Design and applications of bio-inspired quantum materials Mohan Sarovar, Dörthe M. Eisele and K. Birgitta Whaley; 15. Coherent excitons in carbon nanotubes Leonas Valkunas and Darius Abramavicius; Glossary; References; Index.

  17. Medical exposure and effective dose

    International Nuclear Information System (INIS)

    The frequency of radiological diagnosis in Japan and individual population effective dose are reported. Questionnaire on radiological practice was delivered to selected medical facilities. The total number of X-ray diagnosis performed in 1991 was 180,000,000, being age-dependent in both men and women. The chest was the most common site to be examined. The number of X-ray films per examination was the highest for the stomach. The spread of ultrasound has decreased radiological practice in the obstetric field (approximately one sixth between 1979 and 1986). There was an 8-fold increase in the number of X-ray CT as of 1989 during the past decade. The total number of CT scanning in 1989 reached nearly 14,850,000 (about 16 times as much as that of 1979). The number of stomach X-ray screening increased to 7,800,000 which is twice as much as that in 1975. In the dental field, panoramic method brought about a 7-fold increase between 1974 and 1985. The frequency of nuclear medicine diagnosis has slightly increased, reaching 1,400,000 cases in 1992, and 99mTc was the most common nuclide. The total population effective dose of radiography and fluoroscopy was 179,000 mSv. The highest effective dose was associated with gastric X-ray. The effective dose equivalent per diagnosis was estimated to be 1.02 mSv (the total population/total number of radiological diagnosis). The population effective dose per person was 2.3 mSv (population effective dose equivalent/national population), which was equal to the world average of yearly effective dose equivalent of natural radiation. (S.Y.)

  18. Biological dose representation for carbon-ion radiotherapy of unconventional fractionation

    CERN Document Server

    Kanematsu, Nobuyuki

    2016-01-01

    In carbon-ion radiotherapy, single-beam delivery each day in alternate directions has been commonly practiced for operational efficiency, taking advantage of the Bragg peak and the relative biological effectiveness (RBE) for uniform dose conformation to a tumor. The treatment plans are usually evaluated with total RBE-weighted dose, which is however deficient in relevance to the biological effect in the linear-quadratic model due to its quadratic-dose term, or the dose-fractionation effect. In this study, we reformulate the extrapolated response dose (ERD), or synonymously BED, which normalizes the dose-fractionation and cell-repopulation effects as well as the RBE of treating radiation, based on inactivation of a single model cell system and a typical treating radiation in carbon-ion RT. The ERD distribution virtually represents the biological effect of the treatment regardless of radiation modality or fractionation scheme. We applied the ERD formulation to simplistic model treatments and to a preclinical su...

  19. Physics must join with biology in better assessing risk from low-dose irradiation

    International Nuclear Information System (INIS)

    This review summarises the complex response of mammalian cells and tissues to low doses of ionising radiation. This thesis encompasses induction of DNA damage, and adaptive protection against both renewed damage and against propagation of damage from the basic level of biological organisation to the clinical expression of detriment. The induction of DNA damage at low radiation doses apparently is proportional to absorbed dose at the physical/chemical level. However, any propagation of such damage to higher levels of biological organisation inherently follows a sigmoid function. Moreover, low-dose-induced inhibition of damage propagation is not linear, but instead follows a dose-effect function typical for adaptive protection, after an initial rapid rise it disappears at doses higher than ∼0.1-0.2 Gy to cells. The particular biological response duality at low radiation doses precludes the validity of the linear-no-threshold hypothesis in the attempt to relate absorbed dose to cancer. In fact, theory and observation support not only a lower cancer incidence than expected from the linear-no-threshold hypothesis, but also a reduction of spontaneously occurring cancer, a hormetic response, in the healthy individual. (authors)

  20. Low Doses of Ionizing Radiation: Biological Effects and Regulatory Control. Invited papers and discussions from a conference in Seville, Spain, 17-21 November 1997

    International Nuclear Information System (INIS)

    Radiological protection is concerned with the limitation of the consequential risks from exposure to ionising radiation. In recent years, there has been much debate about the validity of one of the fundamental bases of the present system for the limitation of these risks, i.e., at the low dose rates with which we are usually concerned in routine activities, the incremental increase in the risk of stochastic effects (primarily cancer) is linearly related to the additional radiation dose above that from the natural background. This is the linear, no-threshold (LNT) dose-response paradigm adopted by the ICRP in developing its recommendations. Re-analysis and interpretation of existing data, and new data on effects that may (or may not) be of relevance to cancer induction, have led to proposals for contrary supralinear, threshold and hormetic (beneficial) response relationships at low doses. It was the purpose of this conference to provide a forum to examine the latest information and debate the issues. A detailed meeting report has been given in an earlier issue of this journal (Wakeford R and Tawn E J 1998 J. Radiol. Prot. 18 52-6), and the majority of the short papers presented at the conference were issued, at that time, as an IAEA Technical Document (IAEA TECDOC-976, available free of charge from the IAEA in Vienna). This publication provides the keynote papers, summaries of the discussions and the session chairmen's summaries for each of the set of ten fora, a special session and a final round-table discussion that constituted the main body of the conference. Also included are the papers presented in two introductory background sessions that provided some context for the conference. All of the keynote papers provide, as might be expected, useful summaries of the state of the art in the respective fields. This is particularly so for the fora 8-10 that introduced the discussion of control measures and criteria for intervention, in which circumstance there is, at

  1. Biological radiation effects

    International Nuclear Information System (INIS)

    The book covers all aspects of biological radiation effects and provides the fundamental basis for understanding the necessity of radiation protection as well as applications in radiotherapy. The physical basis is dealt with in some detail, and the effects at the subcellular and the cellular level are thoroughly discussed, taking into account modern developments and techniques. The effects on the human organism are reviewed, both from the point of view of applications in medicine as well as with regard to radiation hazards (teratogenic, gonadal and carcinogenic effects). It can be used by graduate students as an introduction and as a source book for all who want to become acquainted with this important field. It is an extended version of the original German book containing updated information and new material. (orig.) With 273 figs

  2. Biological Effects after Prenatal Irradiation

    International Nuclear Information System (INIS)

    A Task Group of the International Commission on Radiological Protection (ICRP) has finished a report Biological Effects after Prenatal Irradiation (Embryo and Fetus) which has been approved by the Main Commission and Will be Published. Some new important scientific data shall be discussed in this contribution. During the preimplantation period lethality of the mammalian embryo is the dominating radiation effect. However, in mouse strains with genetic predispositions it has been shown that also malformations can be caused. This effect is genetically determined and its mechanisms is different from the induction of malformations during major organogenesis. Radiation exposures during this prenatal period leads ato an increase of genomic instability of cells in the normal appearing fetuses. These radiation effects can be transmitted to the next generation. A renewed analysis of individuals with severe mental retardation after exposures during the 8th to 15th week post conception in Hiroshima and Nagasaki gives evidence that a threshold dose exists for this effect around 300 mGy. This is supported by a number of experimental animal data which have been obtained from cellular and molecular investigations during the brain development. The data show the high radiosensitivity of the developing brain but also the various compensatory mechanisms and the enormous plasticity of these processes. The radiosensitivity varies strongly during the prenatal development. The highest sensitivity is found during the early and mid fetal period which is coinciding with weeks 8-15 post conception in humans. The lowest doses causing persistent damage are in the range of 100 to 300 mGy. For intelligence quotient scores a linear dose response model provides a satisfactory fit. From the experimental data it can be concluded that the fetal stage is most sensitive to the carcinogenic effect in comparison to the other prenatal stages. Such as clear situation cannot be obtained from the

  3. Low level radiation: biological effects

    International Nuclear Information System (INIS)

    It is imperative that physicians and scientists using radiations in health care delivery continue to assess the benefits derived, vs. potential risk, to patients and radiation workers being exposed to radiation in its various forms as part of our health delivery system. Insofar as possible we should assure our patients and ourselves that the benefits outweigh the potential hazards involved. Inferences as to the possible biological effects of low level radiation are generally based on extrapolations from those effects observed and measured following acute exposures to considerably higher doses of radiation. Thus, in order to shed light on the question of the possible biological effects of low level radiation, a wide variety of studies have been carried out using cells in culture and various species of plant and animal life. This manuscript makes reference to some of those studies with indications as to how and why the studies were done and the conclusions that might be drawn there from. In addition reference is made to the handling of this information by scientists, by environmentalists, and by the news media. Unfortunately, in many instances the public has been misled by what has been said and/or written. It is hoped that this presentation will provide an understandable and reasonable perspective on the various appropriate uses of radiation in our lives and how such uses do provide significant improvement in our health and in our quality of life

  4. Stimulation of biological activities using low radiation doses

    International Nuclear Information System (INIS)

    Hormesis is the excitation, or stimulation, by low doses of any agent in any system; high doses inhibit but low doses stimulate. Don Luckey from the University of Florida identified the phenomenon of radiation hormesis, in 1982. After nearly ten years of data surveys and animal tests in many universities to examine the truth about radiation hormesis, we realized the scientific significance of the stimulating effects caused by low levels of radiation exposure. Stimulation with Ionizing radiation presented evidence of increased vigor in plants, bacteria, invertebrates and vertebrates. Most physiologic reactions in living cells are stimulated by low doses of ionizing radiation. This stimulating effect includes enzyme induction, photosynthesis, respiration and growth. Radiation stimulation to the immune system decreases infection and premature death in radiation exposed individuals. (author)

  5. Relationship between biologic tissue heterogeneity and absorbed dose distribution in therapy of oncologic patients with cyclotron U-120 fast neutrons

    International Nuclear Information System (INIS)

    Effect of biological tissue heterogeneity on the absorbed dose distribution of U-120 cyclotron fast neutron beam was studied by estimation and experimental method. It was found that adipose and bone tissues significantly changes the pattern of neutron absorbed dose distribution in patient body. Absorbed dose in adipose layer increase by 20% as compared to the dose in soft biological tissue. Approximation method for estimation of the absorbed dose distribution of fast neutrons in heterogeneities was proposed which could be applied in the dosimetric planning of U-120 cyclotron neutron therapy of neoplasms

  6. The biological effectiveness of antiproton irradiation

    DEFF Research Database (Denmark)

    Holzscheiter, Michael H.; Bassler, Niels; Agazaryan, Nzhde;

    2006-01-01

    Background and purpose: Antiprotons travel through tissue in a manner similar to that for protons until they reach the end of their range where they annihilate and deposit additional energy. This makes them potentially interesting for radiotherapy. The aim of this study was to conduct the first...... ever measurements of the biological effectiveness of antiprotons. Materials and methods: V79 cells were suspended in a semi-solid matrix and irradiated with 46.7 MeV antiprotons, 48 MeV protons, or 60Co c-rays. Clonogenic survival was determined as a function of depth along the particle beams. Dose and...... particle fluence response relationships were constructed from data in the plateau and Bragg peak regions of the beams and used to assess the biological effectiveness. Results: Due to uncertainties in antiproton dosimetry we defined a new term, called the biologically effective dose ratio (BEDR), which...

  7. Low doses effects and gamma radiations low dose rates

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

  9. Dose inhomogeneities at various levels of biological organization

    International Nuclear Information System (INIS)

    Dose inhomogeneities in both tumor and normal tissue, inherent to the application of boron neutron capture therapy (BNCT), can be the result not only of ununiform distribution of 10B at various levels of biological organization, but also of the distribution of the thermal neutrons and of the energy depositions from more energetic neutrons and other radiations comprising the externally-applied beams. The severity of the problems resulting from such inhomogeneities, and approaches to evaluating them, are illustrated by three examples, at the macro, micro and intermediate levels

  10. The impact of different dose response parameters on biologically optimized IMRT in breast cancer

    Science.gov (United States)

    Costa Ferreira, Brigida; Mavroidis, Panayiotis; Adamus-Górka, Magdalena; Svensson, Roger; Lind, Bengt K.

    2008-05-01

    The full potential of biologically optimized radiation therapy can only be maximized with the prediction of individual patient radiosensitivity prior to treatment. Unfortunately, the available biological parameters, derived from clinical trials, reflect an average radiosensitivity of the examined populations. In the present study, a breast cancer patient of stage I II with positive lymph nodes was chosen in order to analyse the effect of the variation of individual radiosensitivity on the optimal dose distribution. Thus, deviations from the average biological parameters, describing tumour, heart and lung response, were introduced covering the range of patient radiosensitivity reported in the literature. Two treatment configurations of three and seven biologically optimized intensity-modulated beams were employed. The different dose distributions were analysed using biological and physical parameters such as the complication-free tumour control probability (P+), the biologically effective uniform dose (\\bar{\\bar{D}} ), dose volume histograms, mean doses, standard deviations, maximum and minimum doses. In the three-beam plan, the difference in P+ between the optimal dose distribution (when the individual patient radiosensitivity is known) and the reference dose distribution, which is optimal for the average patient biology, ranges up to 13.9% when varying the radiosensitivity of the target volume, up to 0.9% when varying the radiosensitivity of the heart and up to 1.3% when varying the radiosensitivity of the lung. Similarly, in the seven-beam plan, the differences in P+ are up to 13.1% for the target, up to 1.6% for the heart and up to 0.9% for the left lung. When the radiosensitivity of the most important tissues in breast cancer radiation therapy was simultaneously changed, the maximum gain in outcome was as high as 7.7%. The impact of the dose response uncertainties on the treatment outcome was clinically insignificant for the majority of the simulated patients

  11. The impact of different dose-response parameters on biologically optimized IMRT in breast cancer

    International Nuclear Information System (INIS)

    The full potential of biologically optimized radiation therapy can only be maximized with the prediction of individual patient radiosensitivity prior to treatment. Unfortunately, the available biological parameters, derived from clinical trials, reflect an average radiosensitivity of the examined populations. In the present study, a breast cancer patient of stage I-II with positive lymph nodes was chosen in order to analyse the effect of the variation of individual radiosensitivity on the optimal dose distribution. Thus, deviations from the average biological parameters, describing tumour, heart and lung response, were introduced covering the range of patient radiosensitivity reported in the literature. Two treatment configurations of three and seven biologically optimized intensity-modulated beams were employed. The different dose distributions were analysed using biological and physical parameters such as the complication-free tumour control probability (P+), the biologically effective uniform dose, dose volume histograms, mean doses, standard deviations, maximum and minimum doses. In the three-beam plan, the difference in P+ between the optimal dose distribution (when the individual patient radiosensitivity is known) and the reference dose distribution, which is optimal for the average patient biology, ranges up to 13.9% when varying the radiosensitivity of the target volume, up to 0.9% when varying the radiosensitivity of the heart and up to 1.3% when varying the radiosensitivity of the lung. Similarly, in the seven-beam plan, the differences in P+ are up to 13.1% for the target, up to 1.6% for the heart and up to 0.9% for the left lung. When the radiosensitivity of the most important tissues in breast cancer radiation therapy was simultaneously changed, the maximum gain in outcome was as high as 7.7%. The impact of the dose-response uncertainties on the treatment outcome was clinically insignificant for the majority of the simulated patients. However, the jump

  12. Biological Effects of Ionizing Radiation

    International Nuclear Information System (INIS)

    The aim of this work is to verify the existence of the adaptive response phenomenon induced by low doses of ionizing radiation in living cells.A wild-type yeast Saccharomyces cerevisiae (Baker's yeast) was chosen as the biological target.As a parameter to quantify the sensibility of the target to radiation, the Lethal Dose 50 (LD50 ) was observed. In our experimental condition a value of (60 ± 1) Gy was measured for LD50 with Dose Rate of (0.44 ± 0.03) Gy/min. The method employed to show up the adaptive response phenomenon consisted in exposing the sample to low ''conditioning'' doses, which would initiate these mechanisms. Later the samples with and without conditioning were exposed to higher ''challenging'' doses (such as LD50), and the surviving fractions were compared. In order to maximize the differences, the doses and the time between irradiations were varied. The best results were obtained with both a conditioning dose of (0.44 ± 0.03) Gy and a waiting time of 2 hs until the application of the challenging dose. Following this procedures the 80% of the conditioned samples has survived, after receiving the application of the LD50. The adaptive response phenomenon was also verified for a wide range of challenging doses

  13. Near-term and late biological effects of acute and low-dose-rate continuous gamma-ray exposure in dogs and monkeys

    International Nuclear Information System (INIS)

    Monkeys (Macaca mulatta) and dogs (beagle) were given thirteen 100-rad gamma-ray doses at 28-day intervals. The comparative response (inury and recovery) of the hematopoietic system of the two species was observed at 7-day intervals during the exposure regime. At 84 days after the thirteenth gamma-ray dose, the 1300-rad conditioned and control dogs and monkeys were challenged continuously with gamma rays at 35 r/day until death to determine the amount of radiation-induced injry remaining in conditioned animals as a reduction in mean survival time. Dogs (50%) and monkeys (8%) died from injury incurred during conditioning exposures. Thus, the comparative response (in terms of lethality) of dogs and monkeys to dose protraction by acute dose fractionation was similar to what we would expect from a single acute dose. The mean survival times for nonconditioned dogs and monkeys during continuous exposure at 35 R/day were the same (approx. 1400 h). Thus, the hematopoietic response of the two species by this method of dose protraction was not significantly different. Mean survival times of conditioned dogs and monkeys during the continuous 35-R/day gamma-ray challenge exposure were greater (significant in dogs but not in monkeys) than for their control counterparts. Thus, long-term radiation-induced injury was not measurable by this method. Conditioning doses of more than 4 times the acute LD5030 in dogs and approximately 2 times that in monkeys served only to increase both mean survival time and variance in a gamma-ray stress environment with a dose rate of 35 Rat/day

  14. Low dose effects. Adaptive response

    International Nuclear Information System (INIS)

    The purpose of this work was to evaluate if there are disturbancies in adaptive response when lymphocytes of people living on the polluted with radionuclides area after Chernobyl disaster and liquidators suffered from accident have been investigated. The level of lymphocytes with micronuclei have been scored in Moscow donors and people living in Bryansk region with the degree of contamination 15 - 40 Ci/km. The doses that liquidators have been obtained were not higher then 25 cGy. The mean spontaneous level of MN in control people and people from Chernobyl zones does't differ significantly but the individual variability in the mean value between two populations does not differ significantly too. And in this case it seems that persons of exposed areas. Then another important fact in lymphocytes of people living on polluted areas the chronic low dose irradiation does not induce the adaptive response. In Moscow people in most cases (≅ 59 %) the adaptive response is observed and in some cases the demonstration of adaptive response is not significant (≅1%). In Chernobyl population exposed to chronic low level, low dose rate irradiation there are fewer people here with distinct adaptive response (≅38%). And there appear beings with increased radiosensitivity after conditioned dose. Such population with enhanced radiosensitivity have not observed in Moscow. In liquidators the same types of effects have been registered. These results have been obtained on adults. Adaptive response in children 8 - 14 old population living in Moscow and in Chernobyl zone have been investigated too. In this case the spontaneous level of MN is higher in children living in polluted areas, after the 1.0 Gy irradiation the individual variability is very large. Only 5 % of children have distinct is very large. Only 5 % of children have distinct adaptive response, the enhancement of radiosensitivity after conditioned dose is observed. (authors)

  15. Effects of low doses of ionizing radiation

    International Nuclear Information System (INIS)

    Several groups of human have been irradiated by accidental or medical exposure, if no gene defect has been associated to these exposures, some radioinduced cancers interesting several organs are observed among persons exposed over 100 to 200 mSv delivered at high dose rate. Numerous steps are now identified between the initial energy deposit in tissue and the aberrations of cell that lead to tumors but the sequence of events and the specific character of some of them are the subject of controversy. The stake of this controversy is the risk assessment. From the hypothesis called linear relationship without threshold is developed an approach that leads to predict cancers at any tiny dose without real scientific foundation. The nature and the intensity of biological effects depend on the quantity of energy absorbed in tissue and the modality of its distribution in space and time. The probability to reach a target (a gene) associated to the cancerating of tissue is directly proportional to the dose without any other threshold than the quantity of energy necessary to the effect, its probability of effect can be a more complex function and depends on the quality of the damage produced as well as the ability of the cell to repair the damage. These two parameters are influenced by the concentration of initial injuries in the target so by the quality of radiation and by the dose rate. The mechanisms of defence explain the low efficiency of radiation as carcinogen and then the linearity of effects in the area of low doses is certainly the least defensible scientific hypothesis for the prediction of the risks. (N.C.)

  16. Biological radiation effects

    International Nuclear Information System (INIS)

    This work examines ionizing radiations: what they are, where they come from, their actions and consequences, finally the norms and preventive measures necessary to avoid serious contamination, whether the individual or the population in general is involved. Man has always been exposed to natural irradiation, but owing to the growing use of ionizing radiations both in medicine and in industry, not to mention nuclear tests and their use as an argument of dissuasion, the irradiation of human beings is increasing daily. Radioactive contamination does remain latent, apart from acute cases, but this is where the danger lies since the consequences may not appear until long after the irradiation. Of all biological effects due to the action of radioelements the genetic risk is one of the most important, affecting the entire population and especially the generations to come. The risk of cancer and leukemia induction plays a substantial part also since a large number of people may be concerned, depending on the mode of contamination involved. All these long-term dangers do not of course exclude the various general or local effects to which the individual alone may be exposed and which sometimes constitute a threat to life. As a result the use of ionizing radiations must be limited and should only be involved if no other process can serve instead. The regulations governing radioelements must be stringent and their application strictly supervised for the better protection of man. This protection must be not only individual but also collective since pollution exists in air, water and land passes to plants and animals and finally reaches the last link in the food chain, man

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-09-01

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

  18. The biological basis for dose limitation to the skin

    International Nuclear Information System (INIS)

    Ionizing radiation may cause deterministic effects and cancer. It has been the policy to base dose limits for radiation protection of the skin on the prevention of deterministic effects (1). In the case of cancer in general, dose limitation for radiation protection is based on limiting excess cancer mortality to low levels of radiation. Since skin cancers are seldom lethal, the general radiation protection standards will protect against an increase in excess mortality from skin cancer. However, with the dose limits selected to prevent deterministic effects, there is a significant probability of an excess incidence of skin cancer occurring as a result of exposure during a working lifetime. The induction of skin cancer by radiation is influenced significantly by subsequent exposure to ultraviolet radiation (UVR) from sunlight. This finding raises not only interesting questions about the mechanisms involved, but also about the differences in risk of skin cancer in different populations. The amount and distribution of melanin in the skin determines the degree of the effect of UVR. This paper discusses the mechanisms of the induction of both deterministic and stochastic effects in skin exposed to radiation in relation to radiation protection. (author)

  19. The influence of low doses of ionizing radiation on biological systems

    International Nuclear Information System (INIS)

    Recent results concerning possible beneficial effects of low doses of ionizing radiation on biological systems are summarized. It is also pointed out on the basis of existing evidence that harmful effects on living organisms take place not only in the case of excess but also in the case of deficiency of ionizing radiation. Possibility of using radio-enhanced ultralow luminescence for studying hormesis phenomena is discussed. 24 refs., 4 figs. (author)

  20. Current issues in carcinogenic effect of low-dose radiation

    International Nuclear Information System (INIS)

    A review of publications dealing with study of radiation sources and biological evaluation of increasing doses of people irradiation under occupational and usual living conditions is presented. The existing natural and artifial irradiation sources are considered. It is noted that all types of ionizing radiations are characterized by high carcinogenic efficiency and can induce benign and malignant tumors practically in all organs. Statistically reliable data in experimental and epidemiological investigations were recorded under the effect of large and mean doses. Minor radiation doses not responsible for visible functional and morphological changes in early periods can cause pathological changes in delayed periods. The data on carcinogenic effect of relatively small radiation doses are available

  1. Complex damage, low doses and Bystander effects

    International Nuclear Information System (INIS)

    Ionizing radiations of all types can produce a wide array of biological effects that overlap with those produced by many other genotoxic agents. Ionizing radiation, however, has unique features that sets it apart and these features are likely to dominate its modes of action and consequences, especially at low doses. Radiation insult is always in the form of highly structured 'tracks' along the paths of moving charged particles. This feature largely determines the spectrum of initial DNA damage produced in cells or people, the repairability of the damage by cellular processes, and its spatial and temporal distribution in the irradiated material. At the DNA level a substantial proportion of the initial damage is clustered over a few base pairs within a few nanometres of the track, thereby forming local complex damage consisting of several strand breaks and/or damaged bases. Simple double-strand breaks are in the minority compared to more complex combinations, even from so-called sparsely-ionizing (or low-LET) radiations. At low doses, the nature of the radiation tracks determines also the distributions of the primary complex lesions over the larger subcellular, cellular and tissue scales. At exposure levels of natural background radiation and also in most situations of occupational or diagnostic medical exposure, cells are traversed by single isolated individual tracks, so it is the biological capabilities of these single tracks that must determine the probability of harmful effects, if any. Thus, questions relating to the linear no-threshold hypothesis versus thresholds, hormesis, hypersensitivity, and so on, reduce at the low-dose end to understanding the capabilities and consequences of a single track, or a small number, and the persistence and range of its influence in tissue. Much is now understood about the nature and consequences of immediate 'targeted' radiation damage in cells from radiation tracks in them and near their DNA. However, over the last decade

  2. A Systems Biology Approach Reveals the Dose- and Time-Dependent Effect of Primary Human Airway Epithelium Tissue Culture After Exposure to Cigarette Smoke In Vitro

    OpenAIRE

    Carole Mathis; Stephan Gebel; Carine Poussin; Vincenzo Belcastro; Alain Sewer; Dirk Weisensee; Arnd Hengstermann; Sam Ansari; Sandra Wagner; Peitsch, Manuel C; Julia Hoeng

    2015-01-01

    To establish a relevant in vitro model for systems toxicology-based mechanistic assessment of environmental stressors such as cigarette smoke (CS), we exposed human organotypic bronchial epithelial tissue cultures at the air liquid interface (ALI) to various CS doses. Previously, we compared in vitro gene expression changes with published human airway epithelia in vivo data to assess their similarities. Here, we present a follow-up evaluation of these in vitro transcriptomics data, using comp...

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

    OpenAIRE

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

    2010-01-01

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

  4. From body burden to effective dose equivalent

    International Nuclear Information System (INIS)

    The necessary data to calculate the effective committed dose equivalent and the effective dose-equivalent rate from measured body burdens are presented. Both ingestion and inhalation intakes are considered, for single intake as well as for continuous exposure

  5. Quantum Effects in Biological Systems

    CERN Document Server

    2016-01-01

    Since the last decade the study of quantum mechanical phenomena in biological systems has become a vibrant field of research. Initially sparked by evidence of quantum effects in energy transport that is instrumental for photosynthesis, quantum biology asks the question of how methods and models from quantum theory can help us to understand fundamental mechanisms in living organisms. This approach entails a paradigm change challenging the related disciplines: The successful framework of quantum theory is taken out of its low-temperature, microscopic regimes and applied to hot and dense macroscopic environments, thereby extending the toolbox of biology and biochemistry at the same time. The Quantum Effects in Biological Systems conference is a platform for researchers from biology, chemistry and physics to present and discuss the latest developments in the field of quantum biology. After meetings in Lisbon (2009), Harvard (2010), Ulm (2011), Berkeley (2012), Vienna (2013), Singapore (2014) and Florence (2015),...

  6. Non-Linear Dose Response Relationships in Biology, Toxicology, and Medicine (June 8-10, 2004). Final Report

    International Nuclear Information System (INIS)

    The conference attracts approximately 500 scientists researching in the area of non-linear low dose effects. These scientists represent a wide range of biological/medical fields and technical disciplines. Observations that biphasic dose responses are frequently reported in each of these areas but that the recognition of similar dose response relationships across disciplines is very rarely appreciated and exploited. By bringing scientist of such diverse backgrounds together who are working on the common area of non-linear dose response relationships this will enhance our understanding of the occurrence, origin, mechanism, significance and practical applications of such dose response relationships

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

    International Nuclear Information System (INIS)

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

  8. Biological monitoring to determine worker dose in a butadiene processing plant

    Energy Technology Data Exchange (ETDEWEB)

    Bechtold, W.E.; Hayes, R.B. [National Cancer Inst., Bethesda, MD (United States)

    1995-12-01

    Butadiene (BD) is a reactive gas used extensively in the rubber industry and is also found in combustion products. Although BD is genotoxic and acts as an animal carcinogen, the evidence for carcinogenicity in humans is limited. Extrapolation from animal studies on BD carcinogenicity to risk in humans has been controversial because of uncertainties regarding relative biologic exposure and related effects in humans vs. experimental animals. To reduce this uncertainty, a study was designed to characterize exposure to BD at a polymer production facility and to relate this exposure to mutational and cytogenetic effects. Biological monitoring was used to better assess the internal dose of BD received by the workers. Measurement of 1,2-dihydroxy-4-(N-acetylcysteinyl) butane (M1) in urine served as the biomarker in this study. M1 has been shown to correlate with area monitoring in previous studies. Most studies that relate exposure to a toxic chemical with its biological effects rely on exposure concentration as the dose metric; however, exposure concentration may or may not reflect the actual internal dose of the chemical.

  9. Higher Biologically Effective Dose of Radiotherapy Is Associated With Improved Outcomes for Locally Advanced Non–Small Cell Lung Carcinoma Treated With Chemoradiation: An Analysis of the Radiation Therapy Oncology Group

    International Nuclear Information System (INIS)

    Purpose: Patients treated with chemoradiotherapy for locally advanced non–small-cell lung carcinoma (LA-NSCLC) were analyzed for local-regional failure (LRF) and overall survival (OS) with respect to radiotherapy dose intensity. Methods and Materials: This study combined data from seven Radiation Therapy Oncology Group (RTOG) trials in which chemoradiotherapy was used for LA-NSCLC: RTOG 88-08 (chemoradiation arm only), 90-15, 91-06, 92-04, 93-09 (nonoperative arm only), 94-10, and 98-01. The radiotherapeutic biologically effective dose (BED) received by each individual patient was calculated, as was the overall treatment time-adjusted BED (tBED) using standard formulae. Heterogeneity testing was done with chi-squared statistics, and weighted pooled hazard ratio estimates were used. Cox and Fine and Gray’s proportional hazard models were used for OS and LRF, respectively, to test the associations between BED and tBED adjusted for other covariates. Results: A total of 1,356 patients were analyzed for BED (1,348 for tBED). The 2-year and 5-year OS rates were 38% and 15%, respectively. The 2-year and 5-year LRF rates were 46% and 52%, respectively. The BED (and tBED) were highly significantly associated with both OS and LRF, with or without adjustment for other covariates on multivariate analysis (p < 0.0001). A 1-Gy BED increase in radiotherapy dose intensity was statistically significantly associated with approximately 4% relative improvement in survival; this is another way of expressing the finding that the pool-adjusted hazard ratio for survival as a function of BED was 0.96. Similarly, a 1-Gy tBED increase in radiotherapy dose intensity was statistically significantly associated with approximately 3% relative improvement in local-regional control; this is another way of expressing the finding that the pool-adjusted hazard ratio as a function of tBED was 0.97. Conclusions: Higher radiotherapy dose intensity is associated with improved local-regional control

  10. Ion irradiation and the biological effect of immune system

    International Nuclear Information System (INIS)

    Ion irradiation exists broadly in the people's life. It can induce a series of the biological effect in body depending on the different type and dose of ionization. This article expound the effect of ion irradiation on the biological function of immune system, affording the theorial guide in the appreciation, precaution and treatment of irradiation injury. (authors)

  11. Chronic radionuclide low dose exposure for non-human biota: challenges in establishing links between speciation in the exposure sources, bioaccumulation and biological effects. Uranium in aquatic ecosystems: A case-study

    International Nuclear Information System (INIS)

    In the field of environmental radioprotection, the knowledge gaps concern situations leading to chronic exposure at the lower doses typical of the living conditions of organisms influenced by radioactive releases. For any radionuclide and ecosystem, the specificities of these situations are as followed: (i) various chemical forms occur in the environment as a function of the physico-chemical conditions of the medium; (ii) each transfer from one component to another can lead to a modification of these forms with a 'chemical form-specific' mobility and bioavailability; (iii) different categories of non-radioactive toxicants are simultaneously present. In this multipollution context, the biological effects of ionising radiation may be exacerbated or reduced with the potential for action or interaction of all the pollutants present simultaneously. These situations of chronic exposure at low levels are likely to cause toxic responses distinct from those observed after acute exposure at high doses since long-term accumulation mechanisms in cells and tissues may lead to microlocalised accumulation in some target cells or subcellular components. The assessment of these mechanisms is primordial with regard to internal exposure to radionuclides since they increase locally both the radionuclide concentration and the delivered dose, coupling radiological and chemical toxicity. This is the main purpose of the ENVIRHOM research programme, recently launched at IRSN. After a global overview of the experimental strategy and of the first results obtained for phytoplankton and uranium, this paper scans the state of art for uranium within freshwaters and underlines inconsistency encountered when one wants to carry out an Ecological Risk Assessment (ERA) on the chemical or on the radiological standpoint. This example argues for future research needs in order to establish well-defined relationship between chemo-toxicity and radiotoxicity for internal contamination. The operational aim

  12. Biological radiation effects

    International Nuclear Information System (INIS)

    The stages of processes leading to radiation damage are studied, as well as, the direct and indirect mechanics of its production. The radiation effects on nucleic acid and protein macro moleculas are treated. The physical and chemical factors that modify radiosensibility are analysed, in particular the oxygen effects, the sensibilization by analogues of nitrogen bases, post-effects, chemical protection and inherent cell factors. Consideration is given to restoration processes by excision of injured fragments, the bloching of the excision restoration processes, the restoration of lesions caused by ionizing radiations and to the restoration by genetic recombination. Referring to somatic effects of radiation, the early ones and the acute syndrome of radiation are discussed. The difference of radiosensibility observed in mammalian cells and main observable alterations in tissues and organs are commented. Referring to delayed radiation effects, carcinogeneses, alterations of life span, effects on growth and development, as well as localized effects, are also discussed

  13. A review of in vitro dose-effect relationships

    International Nuclear Information System (INIS)

    One of the principal reasons for investigating the relationship between absorbed dose and the number of chromosome aberrations per cell in lymphocytes taken from samples of human peripheral blood is to obtain a calibration curve for biological dosimetry. Factors affecting the radiation-induced aberration yield in vitro of T lymphocytes are reviewed under the following heads: temperature, oxygen effect, inter-mitotic death, mitotic delay, dose rate background of aberrations in normal humans, mathematical representation. (U.K.)

  14. Low doses of ionizing radiation: Relationship between biological benefit and damage induction. A synopsis

    International Nuclear Information System (INIS)

    Absorption of ionizing radiation in biological tissue stochastically interacts with constituent atoms and molecules and always generates energy deposition (track) events accompanied by bursts of reactive oxygen species (ROS). These ROS are quite similar to those ROS that arise abundantly and constantly by normal oxidative metabolism. ROS effects from either source need attention when assessing radiation-induced alterations in biological structure and function. Endogenous ROS alone induce about 106 DNA oxyadducts per cell per day compared to about 5x10-3 total DNA damage per average cell per day from background radiation exposure (1 mGy per year). At this background level, the corresponding ratio of probabilities of endogenous versus radiogenic DNA double strand breaks (DSBs) per cell per day is about 103 with some 25-40 % of low-LET caused radiogenic DNA-DSBs being of the multi-damage-site type. Radiogenic DNA damage increases in proportion to absorbed dose over a certain dose range. By evolution, tissues possess physiological mechanisms of protection against an array of potentially toxic agents, externally from the environment and endogenously from metabolism, mainly against the abundantly and constantly produced ROS. Ad hoc protection operates at a level that is genetically determined. Following small to moderate perturbation of cell-tissue homeostasis by a toxic impact, adaptive responses develop with a delay and may last from hours to weeks, even months, and aim at protecting the system against renewed insults. Protective responses encompass defense by scavenging mechanisms, DNA repair, damage removal largely by apoptosis and immune responses, as well as changes in cell proliferation. Acute low-dose irradiation below about 0.2 Gy can not only disturb cell-tissue homeostasis but also initiate adaptived protection that appears with a delay of hours and may last from less than a day to months. The balance between damage production and adaptive protection favors

  15. Climatic and biological effects

    International Nuclear Information System (INIS)

    The ozone-climate problem has received considerable attention since concern was raised regarding possible threats to stratospheric ozone. Early climatic assessments of reduced ozone focused on the direct solar and longwave effects. Now a number of important feedback mechanisms are recognized as contributing significantly to indirect climatic effects. Although the focus in this chapter is on the climatic effect of reduced ozone, the discussion must include other trace gases as well. Many of the trace gases that interact photochemically to reduce ozone also have important radiative properties. Examples are chlorofluorocarbons (CFCl3 and CF2Cl2), nitrous oxide (N2O), and methane (CH4). Other gases, such as CO2, affect the temperature profile in the atmosphere, which can have an indirect effect on ozone through temperature-dependent reaction rates. The change in ozone, in turn, alters the change in temperature. The direct radiative effect of gases comes about through absorption of solar radiation and absorption and emission of longwave radiation (also referred to as thermal, terrestrial, or infrared radiation). The spectral distribution of solar and longwave radiation is shown. The principal gaseous absorbers of solar radiation are O2 and O3 in the stratosphere and H2O in the troposphere. As discussed in Chapter 2, ozone has absorption bands in the ultraviolet (uv) and visible regions of the solar spectrum. Water vapor absorbs primarily in the near-infrared spectral region

  16. A Bayesian Dose-finding Design for Oncology Clinical Trials of Combinational Biological Agents.

    Science.gov (United States)

    Cai, Chunyan; Yuan, Ying; Ji, Yuan

    2014-01-01

    Treating patients with novel biological agents is becoming a leading trend in oncology. Unlike cytotoxic agents, for which efficacy and toxicity monotonically increase with dose, biological agents may exhibit non-monotonic patterns in their dose-response relationships. Using a trial with two biological agents as an example, we propose a dose-finding design to identify the biologically optimal dose combination (BODC), which is defined as the dose combination of the two agents with the highest efficacy and tolerable toxicity. A change-point model is used to reflect the fact that the dose-toxicity surface of the combinational agents may plateau at higher dose levels, and a flexible logistic model is proposed to accommodate the possible non-monotonic pattern for the dose-efficacy relationship. During the trial, we continuously update the posterior estimates of toxicity and efficacy and assign patients to the most appropriate dose combination. We propose a novel dose-finding algorithm to encourage sufficient exploration of untried dose combinations in the two-dimensional space. Extensive simulation studies show that the proposed design has desirable operating characteristics in identifying the BODC under various patterns of dose-toxicity and dose-efficacy relationships. PMID:24511160

  17. Cytogenetic effects of low-dose radiation

    International Nuclear Information System (INIS)

    The effects of ionizing radiation on chromosomes have been known for several decades and dose-effect relationships are also fairly well established in the mid- and high-dose and dose-rate range for chromosomes of mammalian cells. In the range of low doses and dose rates of different types of radiation few data are available for direct analysis of the dose-effect relationships, and extrapolation from high to low doses is still the unavoidable approach in many cases of interest for risk assessment. A review is presented of the data actually available and of the attempts that have been made to obtain possible generalizations. Attention is focused on some specific chromosomal anomalies experimentally induced by radiation (such as reciprocal translocations and aneuploidies in germinal cells) and on their relevance for the human situation. (author)

  18. Low Dose Effects: Testing the Assumptions

    International Nuclear Information System (INIS)

    Our work is to investigate the biological responses of cells and animals to low doses and low dose rates of low linear energy transfer radiation and to compare the results to the predictions of the Linear No-Threshold (LNT) hypothesis. These experiments indicate that at low dose, none of the assumptions of the LNT hypothesis were supported by the data, either in cells or in animals. If these results from human and rodent cells, and from other animals, are applicable to humans, the data further indicate that the use of the LNT hypothesis for radiation protection purposes is not conservative but may actually increase the overall risk of cancer

  19. Radiobiological impact of dose calculation algorithms on biologically optimized IMRT lung stereotactic body radiation therapy plans

    OpenAIRE

    Liang, X.; Penagaricano, J.; Zheng, D.; Morrill, S.; Zhang, X; Corry, P.; Griffin, R. J.; Han, E. Y.; Hardee, M.; Ratanatharathom, V.

    2016-01-01

    Background The aim of this study is to evaluate the radiobiological impact of Acuros XB (AXB) vs. Anisotropic Analytic Algorithm (AAA) dose calculation algorithms in combined dose-volume and biological optimized IMRT plans of SBRT treatments for non-small-cell lung cancer (NSCLC) patients. Methods Twenty eight patients with NSCLC previously treated SBRT were re-planned using Varian Eclipse (V11) with combined dose-volume and biological optimization IMRT sliding window technique. The total dos...

  20. Biological radiation effects

    International Nuclear Information System (INIS)

    Everyone is exposed to a complex mix of electromagnetic fields (EMF) of different frequencies that permeate our environment. Exposures to these EMF are increasing significantly as technology advances unabated and new applications are found. Technological progress in the broadest sense of the word has always been associated with various hazards and risks, both perceived and real. The industrial, commercial and household application on EMF is no exception. Throughout the world, the general public is concerned that exposure to EMF from such sources as high voltage power lines, broadcasting networks, mobile telephones and their base stations could lead to adverse health consequences, especially in children. As a result, the construction of new power lines and broadcasting and mobile telephone network has met with considerable opposition in many countries. Public exposure to EMF is regulated by a variety of voluntary and legal limits, together with various national safety standards. Guidelines are designed to avoid all identified hazards, from short and long term exposure, recommended limits. The aim of this paper is to report the summary of the actual scientific knowledge about the potential health effects and hazards due to man made EMF and the new tendencies of the social and political choices

  1. Biological effects of mutagenic agents

    International Nuclear Information System (INIS)

    There is an increasing body of evidence that mutagenic agents (biological, chemical and physical) play an important role in the etiology of human diseases. Mutations may occur in the germinal as well as in the somatic cells. Mutations of the germ cells may result on infertility or fertilization of damaged cells, the later leading to abortion or birth of a malformed fetus. Somatic-cells mutations may have various biological effects, depending on the period of the human life at which the mutation occurs. If it occurs during the prenatal life, a teratogenic or carcinogenic effect will be observed. If the somatic cell is damaged during the postnatal life, this will lead to neoplastic transformation. Therefore it is extremely important to know the mutagenic, teratogenic and carcinogenic effects of various biological, chemical and physical agents in order to eliminate them from our environment. (author). 13 refs, 4 figs, 1 tab

  2. The concept of the effective dose

    International Nuclear Information System (INIS)

    Irradiation of the human body by external or internal sources leads mostly to a simultaneous exposure of several organs. However, so far no clear and consistent recommendations for the combination of organ doses and the assessment of an exposure limit under such irradiation conditions are available. Following a proposal described in ICRP-publication 14 one possible concept for the combination of organ doses is discussed in this paper. This concept is based on the assumption that at low doses the total radiation detriment to the exposed person is given by the sum of radiation detriments to the single organs. Taking into account a linear dose-risk relationship, the sum of weighted organ doses leads to the definition of an 'Effective Dose'. The applicability and consequences of this 'Effective Dose Concept' are discussed especially with regard to the assessment of the maximum permissible intake of radionuclides into the human body and the combination of external and internal exposure. (orig.)

  3. Dose Rate Effects in Linear Bipolar Transistors

    Science.gov (United States)

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

    2011-01-01

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

  4. Application of Benchmark Dose (BMD) in Estimating Biological Exposure Limit (BEL) to Cadmium

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Objective To estimate the biological exposure limit (BEL) using benchmark dose (BMD) based on two sets of data from occupational epidemiology. Methods Cadmium-exposed workers were selected from a cadmium smelting factory and a zinc product factory. Doctors, nurses or shop assistants living in the same area served as a control group. Urinary cadmium (UCd) was used as an exposure biomarker and urinary β2-microgloburin (B2M), N-acetyl-β-D-glucosaminidase (NAG) and albumin (ALB) as effect biomarkers. All urine parameters were adjusted by urinary creatinine. Software of BMDS (Version 1.3.2, EPA.U.S.A) was used to calculate BMD. Results The cut-off point (abnormal values) was determined based on the upper limit of 95% of effect biomarkers in control group. There was a significant dose response relationship between the effect biomarkers (urinary B2M, NAG, and ALB) and exposure biomarker (UCd). BEL value was 5 μg/g creatinine for UB2M as an effect biomarker, consistent with the recommendation of WHO. BEL could be estimated by using the method of BMD. BEL value was 3 μg/g creatinine for UNAG as an effect biomarker. The more sensitive the used biomarker is, the more occupational population will be protected. Conclusion BMD can be used in estimating the biological exposure limit (BEL). UNAG is a sensitive biomarker for estimating BEL after cadmium exposure.

  5. Effects of low doses: Proof and inferences

    International Nuclear Information System (INIS)

    It is essential to discuss the plausibility of 'low-dose' effects from environmental exposures. The question, nonetheless, is wrongly labelled, for it is not the magnitude of the dose that matters, but rather the effect. The question thus concerns 'doses with low effects'. More precisely, because the low effects on large populations are not that small, even when epidemiological tools fail to detect them, it would be more accurate to talk about 'doses with undetectable or barely detectable effects'. Hereafter, we describe this 'low-effect dose' concept from the viewpoint of toxicology and epidemiology and discuss the fragile boundary line for these low-effect doses. Next, we review the different types of inference from observed situations (i.e., with high effects) to situations relevant to public health, to characterize the level of confidence to be accorded them. The first type is extrapolation - from higher to lower doses or from higher to lower dose rates. The second type is transposition - from humans to other humans or from animals to humans. The third type can be called 'analogy' as in 'read across' approaches, where QSAR (Quantitative Structure Activity Relationship) methodology can be used. These three types of inferences can be based on an estimate of the 'distance' between observed and predicted areas, but can also rely on knowledge and theories of the relevant mechanisms. The new tools of predictive toxicology are helpful both in deriving quantitative estimates and grounding inferences on sound bases. (author)

  6. Biological dose volume histograms during conformal hypofractionated accelerated radiotherapy for prostate cancer

    International Nuclear Information System (INIS)

    Radiobiological data suggest that prostate cancer has a low α/β ratio. Large radiotherapy fractions may, therefore, prove more efficacious than standard radiotherapy, while radiotherapy acceleration should further improve control rates. This study describes the radiobiology of a conformal hypofractionated accelerated radiotherapy scheme for the treatment of high risk prostate cancer. Anteroposterior fields to the pelvis deliver a daily dose of 2.7 Gy, while lateral fields confined to the prostate and seminal vesicles deliver an additional daily dose of 0.7 Gy. Radiotherapy is accomplished within 19 days (15 fractions). Dose volume histograms, calculated for tissue specific α/β ratios and time factors, predict a high biological dose to the prostate and seminal vesicles (77-93 Gy). The biological dose to normal pelvic tissues is maintained at standard levels. Radiobiological dosimetry suggests that, using hypofractionated and accelerated radiotherapy, high biological radiation dose can be given to the prostate without overdosing normal tissues

  7. Biological radiation effects of Radon in Drosophila

    International Nuclear Information System (INIS)

    In order to contribute to the knowledge on the effects of radon and its decay products, the aim of this investigation is to study the biological effects of radon using Drosophila melanogaster throught the somatic mutation and recombination test (SMART) and the analysis of some adaptative factors exposing larvaes to controlled radon atmosphers, considering that this insect could be used as biological monitor. Using the somatic mutation test a mutagenic effect was observed proportional to radon concentration, into an interval of 1 ± 0.3 to 111 ± 7.4 KBq/m3 equivalent to doses under 0.0106 Gy. The correlation analysis gives a linear (r=0.80) relationship with a positive slope of 0.2217. The same happens when gamma rays are used in the interval of 1 to 20 Gy, given a linear dose-dependent effect (r=0.878) is obtained; nevetheless the slop is smaller (m=0.003) than for radon. Analysing the results of adaptative factors of the nine exposed generations, it was found that probably radon exposition induced dominant lethals during gametogenesis or/and a selection of the more component gamets of the treated individuals in larval state. It was reflected in the significant decrease on fecundity of the generation exposed. Nevertheless the laying eggs had an increase in egg-to-adult viability and the develop velocity was higher than in control for 3 KBq/m3, this suggest that radon concentrations used were able to induce repair mechanisms. These data agree with the Hormesis hypothesis that says: low doses have positive effects on health. It was not possible to obtain a dose-effect relationship except with the develop velocity where it was found a dose-effect inverse proportion. In conclusion, Drosophila melanogaster could be a good system to obtain in vivo damaged induction concentration dependent of radon and its decay products, as well as to study the effects in an exposed population by the analysis of adaptative factors. (Author)

  8. Biological effectiveness of antiproton annihilation

    CERN Document Server

    Holzscheiter, Michael H.; Bassler, Niels; Beyer, Gerd; De Marco, John J.; Doser, Michael; Ichioka, Toshiyasu; Iwamoto, Keisuke S.; Knudsen, Helge V.; Landua, Rolf; Maggiore, Carl; McBride, William H.; Møller, Søren Pape; Petersen, Jorgen; Smathers, James B.; Skarsgard, Lloyd D.; Solberg, Timothy D.; Uggerhøj, Ulrik I.; Withers, H.Rodney; Vranjes, Sanja; Wong, Michelle; Wouters, Bradly G.

    2004-01-01

    We describe an experiment designed to determine whether or not the densely ionizing particles emanating from the annihilation of antiprotons produce an increase in “biological dose” in the vicinity of the narrow Bragg peak for antiprotons compared to protons. This experiment is the first direct measurement of the biological effects of antiproton annihilation. The experiment has been approved by the CERN Research Board for running at the CERN Antiproton Decelerator (AD) as AD-4/ACE (Antiproton Cell Experiment) and has begun data taking in June of 2003. The background, description and the current status of the experiment are given.

  9. Abstracts of papers of international scientific conference 'Fundamental and applied aspects of radiobiology: Biological effects of low doses and radioactive contamination of environment (Radioecological and medical biological consequences of the Chernobyl NPP accident)'

    International Nuclear Information System (INIS)

    The results of research works executed in Belarus, as well as in Ukraine and Russia, on various aspects of the Chernobyl problematic are given: radiation medicine and risks, radiobiological effects and their forecasting, radioecology and agricultural radiology, decontamination and radioactive wastes management, socio economic and psychological problems caused by the Chernobyl NPP accident

  10. Dosimetry in Interventional Radiology - Effective Dose Estimation

    International Nuclear Information System (INIS)

    Interventional radiological procedures can lead to significant radiation doses to patients and to staff members. In order to evaluate the personal doses with respect to the regulatory dose limits, doses measured by dosimeters have to be converted to effective doses (E). Measurement of personal dose equivalent Hp(10) using a single unshielded dosimeter above the lead apron can lead to significant overestimation of the effective dose, while the measurement with dosimeter under the apron can lead to underestimation. To improve the accuracy, measurements with two dosimeters, one above and the other under the apron have been suggested (double dosimetry). The ICRP has recommended that interventional radiology departments develop a policy that staff should wear two dosimeters. The aim of this study was to review the double dosimetry algorithms for the calculation of effective dose in high dose interventional radiology procedures. The results will be used to develop general guidelines for personal dosimetry in interventional radiology procedures. This work has been carried out by Working Group 9 (Radiation protection dosimetry of medical staff) of the CONRAD project, which is a Coordination Action supported by the European Commission within its 6th Framework Program.(author)

  11. Radiation doses and correlated late effects in diagnostic radiology

    International Nuclear Information System (INIS)

    Patient irradiation in diagnostic radiology was estimated from measurements of absorbed doses in different organs, assessment of the energy imparted and retrospective calculations based on literature data. Possible late biological effects, with special aspects on children, were surveyed. The dose to the lens of the eye and the possibility of shielding in carotid angiography was studied as was the absorbed dose to the thyroid gland at cardiac catheterization and angiocardiography in children. Calculations of the mean bone marrow dose and gonad doses were performed in children with chronic skeletal disease revealing large contributions from examinations of organs other than the skeleton. The dose distribution in the breast in mammography was investigated. Comparison of the energy imparted in common roentgen examinations in 1960 and 1975 showed an unexpected low decrease in spite of technical improvements. Reasons for the failing decrease are discussed. The energy imparted to children in urological examinations was reduced significantly due to introduction of high sensitivity screens and omission of dose demanding projections. Contributions to the possible late effects were estimated on the basis of the organ doses assessed. (author)

  12. The mean effective dose for Finn

    International Nuclear Information System (INIS)

    The Finnish population is exposed to ionising radiation from number of sources, both natural and man-made. In this report the updated mean annual effective dose for Finnish people is presented together with the methods used in the dose estimation. The minimum and maximum values of the doses from different sources of ionising radiation are also reported. In 2004, the mean effective dose for a Finn was 3.7 millisievert (mSv). More than half of the dose, 2.0 mSv, is from indoor radon exposure. The dose from indoor radon is estimated using the mean radon concentration in Finnish dwellings (120 Bq/m3) determined in a random sampling study in 1990-1991. Individual annual doses from radon may reach a few hundred millisieverts. Roughly one fourth of the annual effective dose, 1.1 mSv, is caused by the natural background radiation. The internal dose from ingestion and inhalation of terrestrial radionuclides is 0.36 mSv. The estimated annual effective dose due to external radiation from the ground and materials of construction is 0.45 mSv. The dose rate inside Finnish dwellings was determined in 1990-1991, at the same time as the mean radon concentration The dose outdoors is based on the gamma-ray measurements done in 1978-1982. Cosmic radiation also contributes to the natural background radiation which causes annually an effective dose of 0.33 mSv in Finland. Medical uses of radiation account for the largest man-made contribution to the overall total. The estimated mean dose to a Finn from diagnostic nuclear medicine procedures was 0.03 mSv in 2003. The new estimation is based on the study of the usage of diagnostic nuclear medicine in Finland done by the Radiation and Nuclear Safety Authority in 2003. The mean annual effective dose from medical x-rays has been determined the previous time in the middle of 1990s. The result of the review was 0.5 mSv/a. (orig.)

  13. Biological effects of radon in Drosophila

    International Nuclear Information System (INIS)

    The main objective of this investigation, is to study the biological effects of the Radon-222 at low dose in 'Drosophila melanogaster'. It is necessary to mention that these effects will analyze from the genetic point of view for: 1) To evaluate in which form the Radon-222 to low dose it influences in some genetic components of the adaptation in Drosophila, such as: fecundity, viability egg-adult and sex proportion. 2) To evaluate which is the genetic effect that induces the Radon to low dose by means of the SMART technique in Drosophila melanogaster, and this way to try of to identify which is the possible mechanism that causes the genetic damage to somatic level. The carried out investigation was divided in three stages: 1. Tests to the vacuum resistance. 2. Test of somatic mutation, and 3. Determination of the presence of radon daughters on the adult of Drosophila. It is necessary to point out that all the experiments were made by triplicate and in each one of them was placed detectors in preset places. Those obtained results are presented inside the 4 charts included in the present work. (Author)

  14. Activation of chemical biological defense mechanisms and remission of vital oxidative injury by low dose radiation

    Energy Technology Data Exchange (ETDEWEB)

    Yamaoka, K. [Okayama University Medical School, Okayama (Japan); Nomura, T. [Central Research Institute of Electric Power Industry, Tokyo (Japan); Kojima, S. [Science University of Tokyo, Chiba (Japan)

    2000-05-01

    Excessive active oxygen produced in vivo by various causes is toxic. Accumulation of oxidation injuries due to excessive active causes cell and tissue injuries, inducing various pathologic conditions such as aging and carcinogenesis. On the other hand, there are chemical defense mechanisms in the body that eliminate active oxygen or repair damaged molecules, defending against resultant injury. It is interesting reports that appropriate oxidation stress activate the chemical biological defense mechanisms. In this study, to elucidate these phenomena and its mechanism by low dose radiation, we studied on the below subjects. Activation of chemical biological defense mechanisms by low dose radiation: (1) The effects radiation on lipid peroxide (LPO) levels in the organs, membrane fluidity and the superoxide dismutase (SOD) activity were examined in rats and rabbits. Rats were irradiated with low dose X-ray over their entire bodies, and rabbits inhaled vaporized radon spring water, which primarily emitted {alpha}-ray. The following results were obtained. Unlike high dose X-ray, low dose X-ray and radon inhalation both reduced LPO levels and made the state of the SH-group on membrane-bound proteins closer to that of juvenile animals, although the sensitivity to radioactivity varied depending on the age of the animals and among different organs and tissues. The SOD activity was elevated, suggesting that low dose X-ray and radon both activate the host defensive function. Those changes were particularly marked in the organs related to immune functions of the animals which received low dose X-ray, while they were particularly marked in the brain after radon inhalation. It was also found that those changes continued for longer periods after low dose X-irradiation. (2) Since SOD is an enzyme that mediates the dismutation of O{sub 2}- to H{sub 2}O{sub 2}, the question as to whether the resultant H{sub 2}O{sub 2} is further detoxicated into H{sub 2}O and O{sub 2} or not must

  15. Activation of chemical biological defense mechanisms and remission of vital oxidative injury by low dose radiation

    International Nuclear Information System (INIS)

    Excessive active oxygen produced in vivo by various causes is toxic. Accumulation of oxidation injuries due to excessive active causes cell and tissue injuries, inducing various pathologic conditions such as aging and carcinogenesis. On the other hand, there are chemical defense mechanisms in the body that eliminate active oxygen or repair damaged molecules, defending against resultant injury. It is interesting reports that appropriate oxidation stress activate the chemical biological defense mechanisms. In this study, to elucidate these phenomena and its mechanism by low dose radiation, we studied on the below subjects. Activation of chemical biological defense mechanisms by low dose radiation: (1) The effects radiation on lipid peroxide (LPO) levels in the organs, membrane fluidity and the superoxide dismutase (SOD) activity were examined in rats and rabbits. Rats were irradiated with low dose X-ray over their entire bodies, and rabbits inhaled vaporized radon spring water, which primarily emitted α-ray. The following results were obtained. Unlike high dose X-ray, low dose X-ray and radon inhalation both reduced LPO levels and made the state of the SH-group on membrane-bound proteins closer to that of juvenile animals, although the sensitivity to radioactivity varied depending on the age of the animals and among different organs and tissues. The SOD activity was elevated, suggesting that low dose X-ray and radon both activate the host defensive function. Those changes were particularly marked in the organs related to immune functions of the animals which received low dose X-ray, while they were particularly marked in the brain after radon inhalation. It was also found that those changes continued for longer periods after low dose X-irradiation. (2) Since SOD is an enzyme that mediates the dismutation of O2- to H2O2, the question as to whether the resultant H2O2 is further detoxicated into H2O and O2 or not must still be evaluated. Hence, we studied the effect of

  16. Comparison of Personal Dose Equivalent and Effective Dose

    International Nuclear Information System (INIS)

    Some of the work of the Joint ICRP/ICRU Task Group in providing conversion coefficients for personal dose equivalent Hp(10) and in making comparisons with the protection quantity effective dose, E, for monoenergetic photons, neutrons and electrons is described. Because Hp(d) is defined in soft tissue in the body and, at the time of writing the Task Group Report, there were few available calculations of dose equivalent in soft tissue in human phantoms, some approximations were required to examine the behaviour of the quantity. The calibration quantity in the ICRU tissue equivalent slab, Hp.slab(d), has also been examined. In general Hp(10) can provide a good measure of E without underestimation or excessive overestimation, but there are exceptions to this in some circumstances, especially for neutron radiations. Such problems can be alleviated by suitable positioning of personal dosemeters, appropriate to the radiation field to which people are exposed, and ensuring the dosemeters are designed and calibrated to measure Hp(10). (author)

  17. Use of the Concept of Equivalent Biologically Effective Dose (BED) to Quantify the Contribution of Hyperthermia to Local Tumor Control in Radiohyperthermia Cervical Cancer Trials, and Comparison With Radiochemotherapy Results

    International Nuclear Information System (INIS)

    Purpose: To express the magnitude of contribution of hyperthermia to local tumor control in radiohyperthermia (RT/HT) cervical cancer trials, in terms of the radiation-equivalent biologically effective dose (BED) and to explore the potential of the combined modalities in the treatment of this neoplasm. Materials and Methods: Local control rates of both arms of each study (RT vs. RT+HT) reported from randomized controlled trials (RCT) on concurrent RT/HT for cervical cancer were reviewed. By comparing the two tumor control probabilities (TCPs) from each study, we calculated the HT-related log cell-kill and then expressed it in terms of the number of 2 Gy fraction equivalents, for a range of tumor volumes and radiosensitivities. We have compared the contribution of each modality and made some exploratory calculations on the TCPs that might be expected from a combined trimodality treatment (RT+CT+HT). Results: The HT-equivalent number of 2-Gy fractions ranges from 0.6 to 4.8 depending on radiosensitivity. Opportunities for clinically detectable improvement by the addition of HT are only available in tumors with an alpha value in the approximate range of 0.22-0.28 Gy-1. A combined treatment (RT+CT+HT) is not expected to improve prognosis in radioresistant tumors. Conclusion: The most significant improvements in TCP, which may result from the combination of RT/CT/HT for locally advanced cervical carcinomas, are likely to be limited only to those patients with tumors of relatively low-intermediate radiosensitivity.

  18. Biological effects of ionizing radiation

    International Nuclear Information System (INIS)

    In this review radiation produced by the nuclear industry is placed into context with other sources of radiation in our world. Human health effects of radiation, derivation of standards and risk estimates are reviewed in this document. The implications of exposing the worker and the general population to radiation generated by nuclear power are assessed. Effects of radiation are also reviewed. Finally, gaps in our knowledge concerning radiation are identified and current research on biological effects, on environmental aspects, and on dosimetry of radiation within AECL and Canada is documented in this report. (author)

  19. 低剂量辐射复合CO、苯和噪声对大鼠的生物效应研究%The combined biological effects of low dose radiation, carbon monoxide, benzene and noise on rats

    Institute of Scientific and Technical Information of China (English)

    陈伟; 何颖; 侯登勇; 钱甜甜; 莫琳芳; 蒋定文; 王庆蓉; 沈先荣

    2012-01-01

    目的 探讨低剂量辐射复合CO、苯和噪声等复合因素对大鼠生物效应的影响.方法 16只雄性SD大鼠随机分成实验组及对照组.实验组采用CO和苯染毒,并进行低剂量辐射和噪声暴露,对照组正常环境饲养.计数大鼠外周血细胞,检测各脏器指数、骨髓DNA含量,利用双向凝胶电泳和基质辅助激光解析飞行时间串联质谱技术分离、鉴定复合因素导致的大鼠血清差异表达蛋白.结果 与对照组相比,实验组大鼠的肝指数、脾指数、胸腺指数显著降低(t=2.732、4.141、3.053,P<0.05),外周血白细胞、血小板和骨髓DNA含量均显著降低(t=2.211、2.668、11.592,P<0.05).获得了血清蛋白凝胶电泳图谱,软件分析结合手工筛选出12个差异表达蛋白质点,鉴定血浆淀粉样蛋白A4(SAA4),Trichoplein角质细丝结合蛋白(TCHP)和α微管蛋白4A(TUBA4A)3个蛋白质点.结论 低剂量辐射复合CO、苯和噪声对大鼠造血系统、免疫系统损伤明显,导致大鼠血清中某些蛋白表达发生变化,发现差异表达的蛋白与复合因素损伤作用密切相关.%Objective To investigate the combined biological effects of low dose radiation,carbon monoxide,benzene and noise on rats.Methods Sixteen male SD rats were randomly divided into experiment group and control group.The experiment group was exposed to carbon monoxide,benzene,low dose radiation and noise daily,the control group was in common environment.Peripheral blood,organ index,and marrow DNA content were detected.Two-dimensional electrophoresis (2-DE) was performed on serum protein analysis.Differential expressed proteins were identified by a matrix assisted laser desorption/ionization time of flight mass spectrometry (MAIDI-TOF-MS).Results Compared to control group,the liver index,spleen index,thymus index,leukocytes,platelets count,and marrow DNA content of the experiment group were decreased significantly (t =2.732,4.141,3.053,2.211,2.668,11.592,P

  20. Standards in biological dosimetry: A requirement to perform an appropriate dose assessment.

    Science.gov (United States)

    Voisin, Philippe

    2015-11-01

    Every year, many countries perform a significant number of investigations based on biological radiation dose assessment to check suspected or true overexposure by irradiation of radiation workers and individuals of the general population. The scoring of dicentrics in peripheral blood lymphocytes has gradually become the "gold standard" for the biodosimetry-based assessment of accidental situations. Nevertheless, other "classical" biodosimetric methods such as micronuclei, prematurely condensed chromosomes (PCC) and FISH translocations are relevant in some exposure situations, also for surveillance of groups of populations at risk. Historical international intercomparison studies have shown discrepancies among dose-effect curves used to estimate doses from blood samples irradiated between 0 and 4Gy. Recent experimental work performed by the biological dosimetry laboratory of the French Institute for Radiation Protection and Nuclear Safety (IRSN) has shown the impact of some blood harvesting parameters on the mitotic index, and consequently on the quality of dose assessment. Therefore, it was relevant to define the best Quality Assurance (QA) and Quality Control (QC) criteria to harmonize protocols among biodosimetry laboratories. Complementary with several editions of an IAEA technical manual, ISO standards were written with the view of considering the most used chromosome aberrations assays: dicentrics and micronuclei. An important feature of these standards is to address the organization of population triage and laboratories networking that would be required in case of a large nuclear event or malicious act involving radioactive material. These ISO standards are relevant and helpful to implement a coordinated response of several biodosimetry networks in Europe, Japan, Canada, and to support European programs such as MULTIBIODOSE and RENEB. A new important ISO standard on the use of FISH translocations in retrospective dosimetry is now being drafted. PMID:26520381

  1. Effective dose from chest tomosynthesis in children

    International Nuclear Information System (INIS)

    Tomosynthesis (digital tomography) is a recently introduced low-dose alternative to CT in the evaluation of the lungs in patients with cystic fibrosis and pulmonary nodules. Previous studies have reported an adult effective dose of 0.12-0.13 mSv for chest tomosynthesis. The aim of this study was to determine the paediatric effective dose from the dose-area-product. During a 3-y period, 38 children with cystic fibrosis and 36 paediatric oncology patients were examined with chest tomosynthesis, totally 169 posteroanterior and 17 anteroposterior examinations (40 boys and 34 girls, mean age 13.7 y, range 7-20 y). Using recently reported paediatric chest tomosynthesis conversion factors (0.23-1.09 mSv Gy cm-2) corrected for sex, age and energy, the mean posteroanterior effective dose calculated was 0.17 mSv; using the proposed simplified conversion factors of 0.6 (8-10 y), 0.4 (11-14 y) and 0.3 mSv Gy cm-2 (15-19 y), the mean posteroanterior effective dose calculated was 0.15 mSv. As the difference in the calculated effective dose was minor, it is recommendable to use the simplified conversion factors. Using the conversion factor for adult chest tomosynthesis (0.26 mSv Gy cm-2), the mean effective dose was 0.11 mSv. Anteroposterior exposures had considerably higher effective dose. By using conversion factors adapted for children, the calculated risks from radiologic procedures will be more accurate. (authors)

  2. Can results from animal studies be used to estimate dose or low dose effects in humans

    International Nuclear Information System (INIS)

    We have devised a method to extrapolate biological equilibrium levels between animal species and subsequently to humans. Our initial premise was based on the observation that radionuclide retention is normally a function of metabolism so that direct or indirect measures could be described by a power law based on body weights of test animal species. However, we found that such interspecies comparisons ought to be based on the coefficient of the power equation rather than on the exponential parameter. The method is illustrated using retention data obtained from five non-ruminant species (including humans) that were fed radionuclides with different properties. It appears that biological equilibrium level for radionuclides in man can be estimated using data from mice, rats and dogs. The need to extrapolate low-dose effects data obtained from small animals (usually rodents) to humans is not unique to radiation dosimetry or radiation protection problems. Therefore, researchers have reviewed some quantitative problems connected with estimating low-dose effects from other disciplines, both because of the concern about effects induced by the radionuclide moiety of a radiopharmaceutical and those of the nonradioactive component. The possibility of extrapolating low-dose effects calculated from animal studies to humans is discussed

  3. Can results from animal studies be used to estimate dose or low dose effects in humans

    International Nuclear Information System (INIS)

    A method has been devised to extrapolate biological equilibrium levels between animal species and subsequently to humans. Our initial premise was based on the observation that radionuclide retention is normally a function of metabolism so that direct or indirect measures could be described by a power law based on body weights of test animal species. However, we found that such interspecies comparisons ought to be based on the coefficient of the power equation rather than on the exponential parameter. The method is illustrated using retention data obtained from five non-ruminant species (including humans) that were fed radionuclides with different properties. It appears that biological equilibrium level for radionuclides in man can be estimated using data from mice, rats, and dogs. The need to extrapolate low-dose effects data obtained from small animals (usually rodents) to humans is not unique to radiation dosimetry or radiation protection problems. Therefore, some quantitative problems connected with estimating low-dose effects from other disciplines have been reviewed, both because of the concern about effects induced by the radionuclide moiety of a radiopharmaceutical and those of the nonradioactive component. The possibility of extrapolating low-dose effects calculated from animal studies to human is discussed

  4. Development of an inverse optimization package to plan nonuniform dose distributions based on spatially inhomogeneous radiosensitivity extracted from biological images

    International Nuclear Information System (INIS)

    An inverse optimization package which is capable of generating nonuniform dose distribution with subregional dose escalation is developed to achieve maximum equivalent uniform dose (EUD) for target while keeping the critical structure doses as low as possible. Relative cerebral blood volume (rCBV) maps obtained with a dynamic susceptibility contrast-enhanced MRI technique were used to delineate spatial radiosensitivity distributions. The voxel rCBV was converted to voxel radiosensitivity parameters (e.g., α and α/β) based on previously reported correlations between rCBV, tumor grade, and radiosensitivity. A software package, DOSEPAINT, developed using MATLAB, optimizes the beamlet weights to achieve maximum EUD for target while limiting doses to critical structures. Using DOSEPAINT, we have generated nonuniform 3D-dose distributions for selected patient cases. Depending on the variation of the pixel radiosensitivity, the subregional dose escalation can be as high as 35% of the uniform dose as planned conventionally. The target dose escalation comes from both the inhomogeneous radiosensitivities and the elimination of integral target dose constraint. The target EUDs are found to be higher than those for the uniform dose planned ignoring the spatial inhomogeneous radiosensitivity. The EUDs for organs at risk are found to be approximately equal to or lower than those for the uniform dose plans. In conclusion, we have developed a package that is capable of generating nonuniform dose distributions optimized for spatially inhomogeneous radiosensitivity. Subregional dose escalation may lead to increased treatment effectiveness as indicated by higher EUDs. The current development will impact biological image guided radiotherapy

  5. E. Biological effects of radiation on man

    International Nuclear Information System (INIS)

    This report firstly summarises information on the biological hazards of radiation and their relation to radiation dose, and hence estimates the biological risks associated with nuclear power production. Secondly, it describes the basis and present status of radiation protection standards in the nuclear power industry

  6. Biologically based multistage modeling of radiation effects

    Energy Technology Data Exchange (ETDEWEB)

    William Hazelton; Suresh Moolgavkar; E. Georg Luebeck

    2005-08-30

    This past year we have made substantial progress in modeling the contribution of homeostatic regulation to low-dose radiation effects and carcinogenesis. We have worked to refine and apply our multistage carcinogenesis models to explicitly incorporate cell cycle states, simple and complex damage, checkpoint delay, slow and fast repair, differentiation, and apoptosis to study the effects of low-dose ionizing radiation in mouse intestinal crypts, as well as in other tissues. We have one paper accepted for publication in ''Advances in Space Research'', and another manuscript in preparation describing this work. I also wrote a chapter describing our combined cell-cycle and multistage carcinogenesis model that will be published in a book on stochastic carcinogenesis models edited by Wei-Yuan Tan. In addition, we organized and held a workshop on ''Biologically Based Modeling of Human Health Effects of Low dose Ionizing Radiation'', July 28-29, 2005 at Fred Hutchinson Cancer Research Center in Seattle, Washington. We had over 20 participants, including Mary Helen Barcellos-Hoff as keynote speaker, talks by most of the low-dose modelers in the DOE low-dose program, experimentalists including Les Redpath (and Mary Helen), Noelle Metting from DOE, and Tony Brooks. It appears that homeostatic regulation may be central to understanding low-dose radiation phenomena. The primary effects of ionizing radiation (IR) are cell killing, delayed cell cycling, and induction of mutations. However, homeostatic regulation causes cells that are killed or damaged by IR to eventually be replaced. Cells with an initiating mutation may have a replacement advantage, leading to clonal expansion of these initiated cells. Thus we have focused particularly on modeling effects that disturb homeostatic regulation as early steps in the carcinogenic process. There are two primary considerations that support our focus on homeostatic regulation. First, a number of

  7. Biological effects of prenatal irradiation

    International Nuclear Information System (INIS)

    After large releases of radionuclides, exposure of the embryo or fetus can take place by external irradiation or uptake of radionuclies. The embryo and fetus are radiosensitive throughout prenatal development. The quality and extent of radiation effects depend on the development stage. During the preimplantation period (one to 10 days postconception, p.c.) a radiation exposure of at least 0.2 Gy can cause the death of the embryo. Malformations are only observed in rare cases when genetic predisposition exist. Macroscopic, anatomical malformations are induced only after irradiation during the major organogenesis (two to eight weeks p.c.). A radiation dose of about 0.2 Gy is a doubling dose for the malformation risks as extrapolated from experiments with rodents. The human embryo may be more radioresistant. During early fetogenesis (8-15 weeks p.c.) a high radiosensitivity exists for the developmental of the brain. Radiation doses of 1.0 Gy cause severe mental retardation in about 40% of the exposed fetuses. It must be taken into account that a radiation exposure during the fetal period can also induce cancer. It is generally assumed that the risk exists at about the same level as for children. (Author)

  8. Biological effect of radioprotectors. 2. Biological effect of aminothiol radioprotectors

    International Nuclear Information System (INIS)

    The section describes about radio-protective effects on cells and animals, and suppressive effects of mutagenesis and carcinogenesis of aminothiols. Amifostine, NH2-(CH2)3-NH-(CH2)2-SPO3H2 (WR-2721, prodrug), WR-1065 (amifostine-SH form, active principle of WR-2721) and WR-33278 (S-S oxidized form of WR-1065) are mainly discussed. In cells exposed in vitro to 4 mM WR-1065, their survival rates are usually elevated regardless of their types after radiation treatment. In vivo, the author employs the administration dose of 400 mg/kg, which is 2/3 LD50 of amifostine. The prodrug is less toxic than the active form in vivo and reduces the mortality by radiation. Amifostine is an FDA-registered medical for reduction of xerostomia during radiotherapy of head and neck cancer, and of renal toxicity of cisplatin during chemotherapy of advanced ovarian cancer. Hypoxanthine phosphoribosyl transferase (HPRT) mutagenic assay in vitro has revealed anti-mutagenic effect of WR-1065 at 40 M, and also in vivo, the effect is seen in mice after irradiation of X-ray and neutron beam at lower administration doses than that used for lethality test mentioned above. WR-2721 at 400 mg/kg and another aminothiol (WR-151327) have anti-caricinogenic effects in mice against lymphoreticular tumors induced by γ-ray or neutron beam and in rats, at 100 mg/kg WR-2721, against hepatoma development and at 50 mg/kg, against mammary cancer. The compounds are shown to suppress the tumor metastasis in animal models. In vitro, WR-1065 has been shown to reduce the frequency of cell transformation after X-ray or neutron exposure. (T.I.)

  9. Dose-rate effect on chromosomal aberrations induced by 60Co γ-rays irradiation in human peripheral blood lymphocyte

    International Nuclear Information System (INIS)

    To estimate exactly the biological dose of persons exposed to different dose rate, human peripheral blood was exposed to 60Co γ-rays in vitro at low, middle and high dose rates respectively and chromosome samples were prepared, then dose-response curves were established according to the dicentrics and ring frequencies. The result showed that the aberration frequency at same dose level increased with dose rate and there was an obvious dose-rate effect. Absorbed dose estimated with low dose-rate dose-response curve was higher markedly than that with high dose-rate dose-response curve. So, considering the effect of dose-rate, approximate dose-rate dose-response curve should be chosen when absorbed dose estimation and the result will be credible. (authors)

  10. Quantum Effects in Biological Systems

    Science.gov (United States)

    Roy, Sisir

    2014-07-01

    The debates about the trivial and non-trivial effects in biological systems have drawn much attention during the last decade or so. What might these non-trivial sorts of quantum effects be? There is no consensus so far among the physicists and biologists regarding the meaning of "non-trivial quantum effects". However, there is no doubt about the implications of the challenging research into quantum effects relevant to biology such as coherent excitations of biomolecules and photosynthesis, quantum tunneling of protons, van der Waals forces, ultrafast dynamics through conical intersections, and phonon-assisted electron tunneling as the basis for our sense of smell, environment assisted transport of ions and entanglement in ion channels, role of quantum vacuum in consciousness. Several authors have discussed the non-trivial quantum effects and classified them into four broad categories: (a) Quantum life principle; (b) Quantum computing in the brain; (c) Quantum computing in genetics; and (d) Quantum consciousness. First, I will review the above developments. I will then discuss in detail the ion transport in the ion channel and the relevance of quantum theory in brain function. The ion transport in the ion channel plays a key role in information processing by the brain.

  11. The calculation of radial dose from heavy ions: predictions of biological action cross sections

    Science.gov (United States)

    Katz, R.; Cucinotta, F. A.; Zhang, C. X.; Wilson, J. W. (Principal Investigator)

    1996-01-01

    The track structure model of heavy ion cross sections was developed by Katz and co-workers in the 1960s. In this model the action cross section is evaluated by mapping the dose-response of a detector to gamma rays (modeled from biological target theory) onto the radial dose distribution from delta rays about the path of the ion. This is taken to yield the radial distribution of probability for a "hit" (an interaction leading to an observable end-point). Radial integration of the probability yields the cross section. When different response from ions of different Z having the same stopping power is observed this model may be indicated. Since the 1960s there have been several developments in the computation of the radial dose distribution, in the measurement of these distributions, and in new radiobiological data against which to test the model. The earliest model, by Butts and Katz made use of simplified delta ray distribution functions, of simplified electron range-energy relations, and neglected angular distributions. Nevertheless it made possible the calculation of cross sections for the inactivation of enzymes and viruses, and allowed extension to tracks in nuclear emulsions and other detectors and to biological cells. It set the pattern for models of observable effects in the matter through which the ion passed. Here we outline subsequent calculations of radial dose which make use of improved knowledge of the electron emission spectrum, the electron range-energy relation, the angular distribution, and some considerations of molecular excitation, of particular interest both close to the path of the ion and the outer limits of electron penetration. These are applied to the modeling of action cross sections for the inactivation of several strains of E-coli and B. subtilis spores where extensive measurements in the "thin-down" region have been made with heavy ion beams. Such calculations serve to test the radial dose calculations at the outer limit of electron

  12. Effective dose: a radiation protection quantity

    CERN Document Server

    Menzel, H G

    2012-01-01

    Modern radiation protection is based on the principles of justification, limitation, and optimisation. Assessment of radiation risks for individuals or groups of individuals is, however, not a primary objective of radiological protection. The implementation of the principles of limitation and optimisation requires an appropriate quantification of radiation exposure. The International Commission on Radiological Protection (ICRP) has introduced effective dose as the principal radiological protection quantity to be used for setting and controlling dose limits for stochastic effects in the regulatory context, and for the practical implementation of the optimisation principle. Effective dose is the tissue weighted sum of radiation weighted organ and tissue doses of a reference person from exposure to external irradiations and internal emitters. The specific normalised values of tissue weighting factors are defined by ICRP for individual tissues, and used as an approximate age- and sex-averaged representation of th...

  13. Biological effect of nitrogen ion implantation on stevia

    International Nuclear Information System (INIS)

    Dry seed of stevia were implanted by 35∼150 keV nitrogen ions with various doses. The biological effect in M1 was studied. The results showed that nitrogen ion beam was able to induce variation on chromosome structure in root tip cells. The rate of cells with chromosome aberration was increased with ion beam energy and dose added, but there was on significant linear regression relationship between ion dose and aberration rate. The results indicated the seedling height reduced with the increasing of dose for ion beam. The biological effect of nitrogen ion beam on M1 stevia was lower than that of γ-rays. (6 refs., 1 fig., 4 tabs.)

  14. Deuterium effects in cancer biology

    International Nuclear Information System (INIS)

    Since its discovery many experiments were conducted for explaining the effects of deuterium on biological systems. It was observed, in many studies, that by increasing the deuterium concentration, structural, metabolic and functional alterations at different extents are produced, which can lead to organism's death. On the other hand effects of concentration reduction are much less studied. Existing data in literature, with regard to intrinsic deuterium reduction effects on different carcinomas are rather scarce. In vitro studies of deuterium level reduction has evidenced an inhibiting effect upon the cellular proliferation in different tumoral cellular lines: M14 cellular lines (human melanoma), PC3 (prostate cancer) and MCF7 (breast cancer). In vivo researches made on experimental tumours, have shown that the deuterium level reduction determines partial or complete regressions in xenotransplanted tumours, while in veterinary oncological clinic, partial or total tumoral regression were observed in different spontaneous tumours in dogs and cats. (authors)

  15. Biological effects of electromagnetic fields

    International Nuclear Information System (INIS)

    The effects of electromagnetic (em) fields on biological systems were first observed and exploited well over a century ago. Concern over the possible health hazards of human exposure to such fields developed much later. It is now well known that excessive exposure to em fields may have in undesirable biological consequences. Standards were introduced to determine what constitute an excessive exposure and how to avoid it. Current concern over the issue of hazards stems mainly from recent epidemiological studies of exposed populations and also from the results of laboratory experiments in which whole animals are exposed in vivo or tissue and cell cultures exposed in vitro to low levels of irradiation. The underlying fear is the possibility of a causal relationship between chronic exposure to low field levels and some forms of cancer. So far the evidence does not add up to a firm statement on the matter. At present it is not known how and at what level, if at all, can these exposure be harmful to human health. This state of affair does not provide a basis for incorporating the outcome of such research in exposure standards. This paper will give a brief overview of the research in this field and how it is evaluated for the purpose of producing scientifically based standards. The emphasis will be on the physical, biophysical and biological mechanisms implicated in the interaction between em fields and biological systems. Understanding such mechanisms leads not only to a more accurate evaluation of their health implications but also to their optimal utilization, under controlled conditions, in biomedical applications. (author)

  16. Low dose effects detected by micronucleus assay in lymphocytes

    International Nuclear Information System (INIS)

    The effects of low doses of X-rays between 0.01 and 1 Gy were studied on whole blood samples of various individuals using the cytokinesis-blocked lymphocyte micronucleus assay as an endpoint. The adaptive response could be induced in G0 cells by 0.01 Gy followed by 1 Gy challenging dose within a time period of 8 hours, in vitro. The probability distribution of micronucleus increments in those samples which had received very low doses in the range 0.01-0.05 Gy proved to be of asymmetrical type (i.e. lognormal) -very likely to the same shape which has been verified for unirradiated (control) population - while the variable turned to be normally distributed at or above 1 Gy. Profound changes have been experienced in the main characteristics of the linear dose - response relationship and in regression parameters, as well, when successively lessened dose ranges were studied toward 0.01 Gy. In the range below ∼ 0.2 Gy the response were found to be unrelated to the absorbed dose. These findings suggest that in (very) low dose range a higher attention should be needed to biological parameters like repair, protective mechanisms and antioxidant capacities, rather than to the absorbed radiation energy only. (author)

  17. Biological studies of radiation effects

    Energy Technology Data Exchange (ETDEWEB)

    Lawrence, J.H.

    1949-11-16

    This paper discusses procedures for research on biological effects of radiation, using mouse tissue: activation trace analysis including methods and proceedures for handling samples before during and after irradiation; methods and procedures for ion exchange study; method of separation and recovery of copper, iron, zinc, cobalt, pubidium and cesium. Also included are studies of trace elements with radioactive isotopes: the distribution of cobalt 60, zinc 65, and copper 64 in the cytoplasm and nuclei of normal mice and those with tumors. 16 figs., 2 tabs.

  18. Dose-related analgesic effects of flupirtine.

    OpenAIRE

    Hummel, T; Friedmann, T; Pauli, E.; Niebch, G.; Borbe, H. O.; Kobal, G

    1991-01-01

    1. Flupirtine is a novel and, in all probability, centrally acting, analgesic. The present investigation was conducted in order to investigate dose-related effects of perorally administered flupirtine in man, with special regard to specifically analgesic actions, employing a model based on pain-related chemosomatosensory evoked potentials and subjective intensity estimates of painful stimuli. 2. Plasma concentrations of flupirtine measured 2 h after dosing linearly increased as a function of ...

  19. The influence of biological and aerosol parameters of inhaled short-lived radon decay products on human lung dose

    International Nuclear Information System (INIS)

    The purpose of this article is to assess the influence of biological and aerosol parameters on human lung dose with regard to a comparison with the corresponding recommended dose values of the International Commission on Radiological Protection (ICRP). The dose conversion factor which gives the relationship between effective dose and potential alpha energy concentration of inhaled short-lived radon decay products (218Po, 214Pb, 214Bi/214Po) is calculated with a dosimetric approach. The calculations are based on a lung dose model with a structure that is related to the recently recommended ICRP respiratory tract model. Because of the short half-lives of the investigated nuclides, simplifying modification of the model were possible. Firstly, the underlying assumptions of the model are described. Secondly, important input parameters of the model are varied to assess the uncertainty of the dose conversion factor due to uncertainty of these parameters. The main emphasis is focused on biological and aerosol parameter variability like variation of breathing rate and breathing mode, clearance rates, critical cells for the induction of lung cancer, particle size and dispersion of the activity size distributions. The possible range of dose conversion factors is discussed both for indoor and mine aerosol conditions in the framework of the presented dose model. The investigation shows that the dosimetric approach leads to a dose conversion convention which is a factor of more than two times higher than the recommended epidemiological values of the ICRP of 3.9 mSv.WLM-1 for the public and 5.1 mSv.WLM-1 at working places. The dosimetric results yield both for indoor and mine aerosol conditions dose conversion factors in the range of 10 mSv.WLM-1 to 15 mSv.WLM-1 depending on breathing mode. (author)

  20. Depression of mouse aggressive behavior by very low dose X-irradiation and its unusual dose-effect relationship

    International Nuclear Information System (INIS)

    In recent years growing concern has emerged about the biological effectiveness of low radiation doses. It is observed that fighting among male OCR mice usually tends to decrease in mice irradiated with low dose X-rays. An attempt is made, therefore, to examine quantitatively the effects of acute low dose X-ray whole-body exposure on aggressive behavior using a resident-intruder paradigm in which a resident mouse attacks an intruder that entered its territory. (author). 11 refs., 4 tabs

  1. Radiation-induced stress effects following low dose exposure

    International Nuclear Information System (INIS)

    Complete text of publication follows. Recent advances in our understanding of effects of radiation on living cells suggest that fundamentally different mechanisms are operating at low doses compared with high doses. Also, acute low doses appear to involve different response mechanisms compared with chronic low doses. Both genomic instability and so called 'bystander effects' show many similarities with well known cellular responses to oxidative stress. These predominate following low dose exposures and are maximally expressed at doses as low as 5mGy. At the biological level this is not surprising. Chemical toxicity has been known for many years to show these patterns of dose response. Cell signaling and coordinated stress mechanisms appear to dominate acute low dose exposure to chemicals. Adaptation to chemical exposures is also well documented although mechanisms of adaptive responses are less clear. In the radiation field adaptive responses also become important when low doses are protracted or fractionated. Recent data from our group concerning bystander effects following multiple low dose exposures suggest that adaptive responses can be induced in cells which only receive signals from irradiated neighbours. We have data showing delayed and bystander effects in humans, rodents 3 fish species and in prawns following in vitro and/or in vivo irradiation of haematopoietic tissues and, from the aquatic groups, gill and skin/fin tissue. Bystander signals induced by radiation can be communicated from fish to fish in vivo and are detectable as early as the eyed egg stage, i.e. as soon as tissue starts to develop. Using proteomic approaches we have determined that the bystander and the direct irradiation proteomes are different. The former show significant upregulation of 5 proteins with anti-oxidant, regenerative and restorative functions while the direct radiation proteome has 2 upregulated proteins both involved in proliferation. These data have implications for

  2. Problems linked to effects of ionizing radiations low doses

    International Nuclear Information System (INIS)

    The question of exposure to ionizing radiations low doses and risks existing for professional and populations has been asked again, with the recommendations of the International Commission of Radiation Protection (ICRP) to lower the previous standards and agreed as guides to organize radiation protection, by concerned countries and big international organisms. The sciences academy presents an analysis which concerned on epidemiological and dosimetric aspects in risk estimation, on cellular and molecular aspects of response mechanism to irradiation. The observation of absence of carcinogen effects for doses inferior to 200 milli-sieverts and a re-evaluation of data coming from Nagasaki and Hiroshima, lead to revise the methodology of studies to pursue, to appreciate more exactly the effects of low doses, in taking in part, particularly, the dose rate. The progress of molecular and cellular biology showed that the extrapolation from high doses to low doses is not in accordance with actual data. The acknowledge of DNA repair and carcinogenesis should make clearer the debate. (N.C.). 61 refs., 9 annexes

  3. Linking exposure to environmental pollutants with biological effects

    DEFF Research Database (Denmark)

    Sørensen, Mette; Autrup, Herman; Møller, Peter;

    2003-01-01

    Exposure to ambient air pollution has been associated with cancer. Ambient air contains a complex mixture of toxics, including particulate matter (PM) and benzene. Carcinogenic effects of PM may relate both to the content of PAH and to oxidative DNA damage generated by transition metals, benzene......, metabolism and inflammation. By means of personal monitoring and biomarkers of internal dose, biologically effective dose and susceptibility, it should be possible to characterize individual exposure and identify air pollution sources with relevant biological effects. In a series of studies, individual...... setting, biological effects of air pollutants appear mainly related to oxidative stress via personal exposure and not to urban background levels. Future developments include personal time-resolved monitors for exposure to ultrafine PM and PM(2.5,) use of GPS, as well as genomics and proteomics based...

  4. The effective dose in diagnostic radiology

    International Nuclear Information System (INIS)

    Although it was originally not intended, the effective dose is used more frequently to describe the exposure of patients in diagnostic radiology. However, mainly caused by the dependence of the stochastic effects of radiation on age and on the age-dependent frequency of radiological examinations, the formulation of certain constraint conditions is necessary. When quantifying the radiation hazard of the population through diagnostic radiology by means of an average effective dose, a possible overestimation of the hazard has to be compensated for by a correction factor of 0.43. (orig.)

  5. Major cost savings associated with biologic dose reduction in patients with inflammatory arthritis.

    LENUS (Irish Health Repository)

    Murphy, C L

    2015-01-01

    The purpose of this study was to explore whether patients with Inflammatory Arthritis (IA) (Rheumatoid Arthritis (RA), Psoriatic Arthritis (PsA) or Ankylosing Spondylitis (AS)) would remain in remission following a reduction in biologic dosing frequency and to calculate the cost savings associated with dose reduction. This prospective non-blinded non-randomised study commenced in 2010. Patients with Inflammatory Arthritis being treated with a biologic agent were screened for disease activity. A cohort of those in remission according to standardized disease activity indices (DAS28 < 2.6, BASDAI < 4) was offered a reduction in dosing frequency of two commonly used biologic therapies (etanercept 50 mg once per fortnight instead of weekly, adalimumab 40 mg once per month instead of fortnightly). Patients were assessed for disease activity at 3, 6, 12, 18 and 24 months following reduction in dosing frequency. Cost saving was calculated. 79 patients with inflammatory arthritis in remission were recruited. 57% had rheumatoid arthritis (n = 45), 13% psoriatic arthritis (n = 10) and 30% ankylosing spondylitis (n = 24). 57% (n = 45) were taking etanercept and 43% (n = 34) adalimumab. The percentage of patients in remission at 24 months was 56% (n = 44). This resulted in an actual saving to the state of approximately 600,000 euro over two years. This study demonstrates the reduction in biologic dosing frequency is feasible in Inflammatory Arthritis. There was a considerable cost saving at two years. The potential for major cost savings in biologic usage should be pursued further.

  6. The radioinduced membranes injuries as biological dose indicators: mechanisms of studies and practical applications

    International Nuclear Information System (INIS)

    After an accidental overexposure, the assessment of the received dose in biological dosimetry is performed by a method based on the effects of irradiation on the DNA molecule. But this technique shows some limitations; therefore we tried to find new bio-sensors of radiation exposure. We have pointed out that membrane is a critical target of ionising radiation after an in vitro and in vivo overexposure. In vitro, these modifications were involved in the radio-induced apoptotic pathway. The measure of membrane fluidity allowed us to obtain an overall view of cellular membrane. Moreover, in vivo, by changing the lipid nutritional status of animals, our results displayed the important role played by membrane lipid composition in radio-induced membrane alterations. Besides, membrane effects were adjusted by the extracellular physiological control, and in particular by the damages on membrane fatty acid pattern. Finally, we have tested the use of membrane fluidity index as a bio-sensor of radiation exposure on in vivo models and blood samples from medical total body irradiated patients. The results achieved on animal models suggested that the membrane fluidity index was a bio-sensor of radiation exposure. Nevertheless, the observations realised on patients highlight that the effect of the first dose fraction of the radiotherapy treatment had some difficulties to be noticed. Indeed, the combined treatment: chemotherapy and radiotherapy disturbed the membrane fluidity index measures. To conclude, whereas this parameter was not a bio-sensor of irradiation exposure usable in biological dosimetry, it may allow us to assess the radio-induced damages and their cellular but also tissue impacts. (author)

  7. Dosimetry and biological effects of fast neutrons

    International Nuclear Information System (INIS)

    This thesis contains studies on two types of cellular damage: cell reproductive death and chromosome aberrations induced by irradiation with X rays, gamma rays and fast neutrons of different energies. A prerequisite for the performance of radiobiological experiments is the determination of the absorbed dose with a sufficient degree of accuracy and precision. Basic concepts of energy deposition by ionizing radiation and practical aspects of neutron dosimetry for biomedical purposes are discussed. Information on the relative neutron sensitivity of GM counters and on the effective point of measurement of ionization chambers for dosimetry of neutron and photon beams under free-in-air conditions and inside phantoms which are used to simulate the biological objects is presented. Different methods for neutron dosimetry are compared and the experimental techniques used for the investigations of cell reproductive death and chromosome aberrations induced by ionizing radiation of different qualities are presented. Dose-effect relations for induction cell inactivation and chromsome aberrations in three cultured cell lines for different radiation qualities are presented. (Auth.)

  8. Effects of low doses of ionizing radiation; Effets des faibles doses de rayonnements ionisants

    Energy Technology Data Exchange (ETDEWEB)

    Masse, R. [Office de Protection contre les Rayonnements Ionisants, 78 - le Vesinet (France)

    2006-07-01

    Several groups of human have been irradiated by accidental or medical exposure, if no gene defect has been associated to these exposures, some radioinduced cancers interesting several organs are observed among persons exposed over 100 to 200 mSv delivered at high dose rate. Numerous steps are now identified between the initial energy deposit in tissue and the aberrations of cell that lead to tumors but the sequence of events and the specific character of some of them are the subject of controversy. The stake of this controversy is the risk assessment. From the hypothesis called linear relationship without threshold is developed an approach that leads to predict cancers at any tiny dose without real scientific foundation. The nature and the intensity of biological effects depend on the quantity of energy absorbed in tissue and the modality of its distribution in space and time. The probability to reach a target (a gene) associated to the cancerating of tissue is directly proportional to the dose without any other threshold than the quantity of energy necessary to the effect, its probability of effect can be a more complex function and depends on the quality of the damage produced as well as the ability of the cell to repair the damage. These two parameters are influenced by the concentration of initial injuries in the target so by the quality of radiation and by the dose rate. The mechanisms of defence explain the low efficiency of radiation as carcinogen and then the linearity of effects in the area of low doses is certainly the least defensible scientific hypothesis for the prediction of the risks. (N.C.)

  9. Medical irradiation and the use of the ''effective dose equivalent'' concept

    International Nuclear Information System (INIS)

    The aim of this paper is to demonstrate the use of the effective dose for all kinds of medical irradiation. In order to estimate the 'somatic effective dose' the weighting factors recommended by ICRP 26 have been separated into those for somatic effects and for genetic effects. Calculation of the effective dose in diagnostic radiology procedures must consider the various technical parameters which determine the absorbed dose in the various organs, i.e. beam quality, typical entrance dose and the number of films of each view. Knowledge about these parameters is not always well established and therefore the effective dose estimates are very uncertain. The average dose absorbed by various organs in the case of administration of radionuclides to the body depends to a much higher degree on biological parameters than in the case of external irradiation. In contrast to the variability and lack of reliability of biological data, the physical methods for internal dose calculation are quite elaborate. However, these methods have to be extended to involve the target dose from the radioactivity distributed within the remaining parts of the body. An attempt was made to estimate the somatic effective dose for the most common diagnostic X-ray and nuclear medicine procedures. This would make it possible to compare the risk of X-ray and nuclear medicine techniques on a more equitable basis. The collective effective dose from medical irradiation is estimated for various countries on the basis of reported statistical data. (H.K.)

  10. The relationships between radiation doses and their effects

    International Nuclear Information System (INIS)

    Dose-effect relationships have been developed both for the biological effects studied by Radiobiology and the long-term pathological effects (malignant diseases) studied by Radiation Protection. The former approach chiefly considers the primary biological injuries at the cellular level, and the relationship between the dependent variable characteristic of the effect and the dose -an independent variable- has an explanatory meaning. The parameters associated to the independent variable have a biophysical signification and fit into a model of the action of ionizing radiations. In the latter approach, the relationship is pragmatic and the previous parameters are just the results of a curve-fitting procedure realized on experimental or human data. The biophysical models have led to a general formulation associating a linear term to a quadratic term both of them weighted by an exponential term describing cellular killing at the highest doses. To a certain extent the curves obtained for leukemias, bronchopulmonary and breast cancers prove the validity of the pragmatic model

  11. Biological dosimetry by the radiation effects on the skin

    International Nuclear Information System (INIS)

    In cases of partial body over-exposure, the dose estimation with personal monitors or with reconstruction of exposed conditions is often impossible without considerable error. Clinical signs of irradiated skin, such as epilation or moist desquamation have been used as the indicators of doses in the radiological accidents, because each sign has the threshold dose. As hair growth is known to be sensitive to radiation, the dose-effect relationship of the delay of hair regrowth and the reduction in hair length of mice after irradiation were examined to investigate if they can be used as biological dosimeters. Hairs on the dorsal skin of 290 ICR mice (8 weeks old) were shaved and irradiated with a Sr-90/Y-90 β-ray source in the early anagen and the midanagen stages of the hair cycle. Skin doses were from 0.5 to 10 Gy. The time of hair regrowth and the hair length were examined with the scaling loupe. Dose-effect relationship of the delay of hair regrowth and reduction in hair length were both clearly dose dependent, fitting the L-Q or L function depending on the stage. Dose estimation functions were derived from the dose-effect relationship curves. The histological observations suggested that hair growth retardation caused by irradiation in midanagen might be due to the cell death and the depression of mitosis in the hair matrix cells. This dose estimation method was applied to the case who was over-exposed to X-ray on his hand and fingers. The findings showed that hair regrowth delay was a sensitive biological dosimeter in the case of partial body over-exposure, which could be applied as early as a few days after over-exposure. The method was simple and non-invasive to the exposed patient. (author)

  12. The dose-effect relationship and the estimation of carcinogen effects of low dose of ionizing radiation

    International Nuclear Information System (INIS)

    biological effectiveness varies as a function of total dose and dose rate. In conclusion, this report raises doubts on the validity of using linear no threshold relationship for evaluating the carcinogenic risk of low doses ( under 100 mSv) and even more for very low doses( under 10 mSv). This report confirms the inappropriateness of the collective dose concept to evaluate population irradiation risks. (N.C.)

  13. Accounting for biological effectiveness in radiological protection

    International Nuclear Information System (INIS)

    Relative biological effectiveness (RBE) presents a practical problem to radiological protection when attempts are made to ensure that the assessed risks from different types of radiation and different modes of exposure to radiation are commensurate with one another. Unfortunately, the theoretical understanding of RBE is still in the stage of competing explanations and hypotheses. Furthermore, the division of the concept of dose equivalent into a set of concepts for risk assessment and another set for measurement and control has introduced conflicting requirements of a practical nature that are difficult to resolve. Many of those working in radiobiology and radiation protection have perceived the need to increase the quality factors for photon and neutron radiations. It may be more reasonable to change the quality factors for neutrons than for other radiations. The advantages and disadvantages of different methods for accommodating such changes within the dose-equivalent concepts are to be examined. The method of accommodating such a change that has the least practical disadvantages is to increase the quality factors for all secondary particles produced in tissue by neutron radiations by a constant factor. The only disadvantage would be the perception that the quality factors for these secondary particles were not treated in a consistent fashion for all types of ionising radiation. (author)

  14. Effect of column ozone on the variability of biologically effective UV radiation at high southern latitudes.

    Science.gov (United States)

    Sobolev, I

    2000-12-01

    Solar irradiance measurements from Ushuaia (Argentina) and Palmer and McMurdo Stations in Antarctica covering four seasons from mid-1993 through early 1997 have been analyzed and their variations compared with column ozone changes. UV irradiances were weighted for biological effectiveness using a published biological weighting function for dose-dependent inhibition of photosynthesis by phytoplankton from the Weddell Sea. All calculations involved integrated daily UV doses and visible exposures (weighted UV and unweighted visible irradiances, respectively). The results show that daily biologically effective total UV doses underwent large short-term variations at all three sites, with day-to-day increases up to 236% at Ushuaia, 285% at Palmer and 99% at McMurdo. Parallel changes in visible exposure indicated that the total UV changes were preponderantly due to variations in cloudiness. On a 12-month basis, daily biologically effective UV doses correlated strongly with visible exposures (R > or = 0.99). Anticorrelations of total UV with ozone, on the other hand, were poor (R > -0.11). The largest daily biologically effective UV doses, and their day-to-day increases, occurred as part of the normal variability related to cloud cover and were seldom associated with significant ozone depletion. UV dose/visible exposure ratios tended to reflect ozone depletion events somewhat more consistently than UV doses alone. With the Weddell Sea phytoplankton weighting function used in this study, antarctic ozone hole events were seldom readily discernible in the biologically effective UV record. The results suggest that, where the UV sensitivity of organisms was similar to that of the Weddell Sea phytoplankton, seasonal ozone depletion had no appreciable effect on annual primary productivity during the 1993-1997 period. Additional data on the geographical and seasonal variation of biological weighting functions are desirable for more comprehensive assessments of ozone depletion

  15. Estimation of effective dose during hysterosalpingography procedures

    International Nuclear Information System (INIS)

    Hysterosalpingography (HSG) is the most frequently used diagnostic tool to evaluate the endometrial cavity and fallopian tube by using conventional x-ray or fluoroscopy. Determination of the patient radiation doses values from x-ray examinations provides useful guidance on where best to concentrate efforts on patient dose reduction in order to optimize the protection of the patients. The aims of this study were to measure the patients entrance surface air kerma doses (ESA K), effective doses and to compare practices between different hospitals in Sudan. ESA K were measured for patient using calibrated thermo luminance dosimeters (TLDs, Gr-200A). Effective doses were estimated using National Radiological Protection Board (NRPB) software. This study was conducted in five radiological departments: Two Teaching Hospitals (A and D), two private hospitals (B and C) and one University Hospital (E). The mean ESD was 20.1 mGy, 28.9 mGy, 13.6 mGy, 58.65 mGy, 35.7, 22.4 and 19.6 mGy for hospitals A,B,C,D, and E), respectively. The mean effective dose was 2.4 mSv, 3.5 mSv, 1.6 mSv, 7.1 mSv and 4.3 mSv in the same order. The study showed wide variations in the ESDs with three of the hospitals having values above the internationally reported values. Number of x-ray images, fluoroscopy time, operator skills x-ray machine type and clinical complexity of the procedures were shown to be major contributors to the variations reported. Results demonstrated the need for standardization of technique throughout the hospital. The results also suggest that there is a need to optimize the procedures. Local DRLs were proposed for the entire procedures. (author)

  16. Off-Label Biologic Regimens in Psoriasis: A Systematic Review of Efficacy and Safety of Dose Escalation, Reduction, and Interrupted Biologic Therapy

    OpenAIRE

    Elizabeth A. Brezinski; Armstrong, April W.

    2012-01-01

    OBJECTIVES: While off-label dosing of biologic treatments may be necessary in selected psoriasis patients, no systematic review exists to date that synthesizes the efficacy and safety of these off-label dosing regimens. The aim of this systematic review is to evaluate efficacy and safety of off-label dosing regimens (dose escalation, dose reduction, and interrupted treatment) with etanercept, adalimumab, infliximab, ustekinumab, and alefacept for psoriasis treatment. DATA SOURCES AND STUDY SE...

  17. Stimulating effects of low doses of radiation

    International Nuclear Information System (INIS)

    Different ionizing radiations cause biochemical and biophysical changes in the cells of the genotypes according to the application of the doses applied to different organs of the plants, and the manner of their application (acute, chronic, or acute and chronic). The sensitivity of different genotypes, and their tissues, depends on the stage at which their tissues were irradiated as well as on the environmental conditions under which the irradiation was made. Relatively strong doses usually cause some genetic changes in the somatic and generative cells. Small doses can, in some genotypes, stimulate the growth of some tissues to some extent. The stimulating effect on the growth of seedlings of the M2 generation, developed from acute seed irradiation of some genotypes of wheat, barley, and inbred lines of maize and their hybrids is described here. 3 refs, 5 tabs

  18. The biological response of plucked human hair to low-dose radiation: a measure of individual radiosensitivity and a technique for biological dosimetry

    International Nuclear Information System (INIS)

    It is often assumed that the effects of radiation are linear with dose and that high dose effects can be extrapolated to low dose levels. However, there are a variety of mechanisms which can alter the response at low doses. The most important of these relate to induced sensitivity or induced repair mechanisms. It is therefore important that this area is studied in more depth by looking at the molecular effects and damage to cells at low doses. It is well known that there are certain rare genetic syndromes which predispose individuals to cancer, e.g. ataxia telangiectasia. It is also probable that there is a large range of sensitivity in the natural variation of individuals to the risk of radiation-induced cancer. It is proposed that radiosensitivity is studied using stimulated lymphocytes from whole blood and the technique extended to look at the effects in cell cultures established from human hair. Radiation treatment of cell cultures established from plucked human hair has been previously advocated as a non-invasive technique for non-uniform biological dosimetry and it is proposed that these techniques are adapted to the use of hair to estimate individual radiosensitivity. The aim is to establish and optimize these techniques for culturing keratinocytes from plucked human hair follicles with a view to study biological markers for the subsequent assessment of radiosensitivity. Preliminary results are promising and suggest that the technique for culturing keratinocytes from hair presents a feasible approach. Results from this primary cell culture technique and results from the comparison of the micronuclei data obtained from the cell cultures and stimulated lymphocytes will be presented. (author)

  19. Biological effects of progestins in breast cancer.

    Science.gov (United States)

    Pasqualini, J R; Ebert, C; Chetrite, G S

    2001-12-01

    The action of progestins is derived from many factors: structure, affinity for the progesterone receptor or for other steroid receptors, the target tissue considered, the biological response, the experimental conditions, the dose and metabolic transformation. The proliferative response to progestins in human breast cancer cells is contradictory: some progestins inhibit, others stimulate, have no effect at all, or have a dual action. For instance, medroxyprogesterone acetate has a stimulatory effect on breast cancer cells after a short period of treatment, but this effect becomes inhibitory when treatment is prolonged. It has been demonstrated that, in hormone-dependent breast cancer cells, various progestins (nomegestrol acetate, medrogestone, promegestone) are potent sulfatase inhibitory agents. The progestins can also involve the inhibition of the mRNA expression of this enzyme. In another series of studies it was also demonstrated that some progestins are very active in inhibiting 17beta-hydroxysteroid dehydrogenase for the conversion of estrone to estradiol. More recently it was observed that the progestins promegestone and medrogestone stimulate sulfotransferase for the formation of estrogen sulfates. Consequently, the action of progestins in blocking estradiol formation via sulfatase, or in stimulating the effect on sulfotransferase activity, can open interesting and new possibilities in clinical applications in breast cancer. PMID:12227886

  20. Biological in situ Dose Painting for Image-Guided Radiation Therapy Using Drug-Loaded Implantable Devices

    International Nuclear Information System (INIS)

    Purpose: Implantable devices routinely used for increasing spatial accuracy in modern image-guided radiation treatments (IGRT), such as fiducials or brachytherapy spacers, encompass the potential for in situ release of biologically active drugs, providing an opportunity to enhance the therapeutic ratio. We model this new approach for two types of treatment. Methods and Materials: Radiopaque fiducials used in IGRT, or prostate brachytherapy spacers ('eluters'), were assumed to be loaded with radiosensitizer for in situ drug slow release. An analytic function describing the concentration of radiosensitizer versus distance from eluters, depending on diffusion-elimination properties of the drug in tissue, was developed. Tumor coverage by the drug was modeled for tumors typical of lung stereotactic body radiation therapy treatments for various eluter dimensions and drug properties. Six prostate 125I brachytherapy cases were analyzed by assuming implantation of drug-loaded spacers. Radiosensitizer-induced subvolume boost was simulated from which biologically effective doses for typical radiosensitizers were calculated in one example. Results: Drug distributions from three-dimensional arrangements of drug eluters versus eluter size and drug properties were tabulated. Four radiosensitizer-loaded fiducials provide adequate radiosensitization for ∼4-cm-diameter lung tumors, thus potentially boosting biologically equivalent doses in centrally located stereotactic body treated lesions. Similarly, multiple drug-loaded spacers provide prostate brachytherapy with flexible shaping of 'biologically equivalent doses' to fit requirements difficult to meet by using radiation alone, e.g., boosting a high-risk region juxtaposed to the urethra while respecting normal tissue tolerance of both the urethra and the rectum. Conclusions: Drug loading of implantable devices routinely used in IGRT provides new opportunities for therapy modulation via biological in situ dose painting.

  1. Ameliorative effects of low dose/low dose-rate irradiation on reactive oxygen species-related diseases model mice

    International Nuclear Information System (INIS)

    Living organisms have developed complex biological system which protects themselves against environmental radiation, and irradiation with proper dose, dose-rate and irradiation time can stimulate their biological responses against oxidative stress evoked by the irradiation. Because reactive oxygen species are involved in various human diseases, non-toxic low dose/low dose-rate radiation can be utilized for the amelioration of such diseases. In this study, we used mouse experimental models for fatty liver, nephritis, diabetes, and ageing to elucidate the ameliorative effect of low dose/low dose-rate radiation in relation to endogenous antioxidant activity. Single irradiation at 0.5 Gy ameliorates carbon tetrachloride-induced fatty liver. The irradiation increases hepatic anti-oxidative system involving glutathione and glutathione peroxidase, suggesting that endogenous radical scavenger is essential for the ameliorative effect of low dose radiation on carbon tetrachloride-induced fatty liver. Single irradiation at 0.5 Gy ameliorates ferric nitrilotriacetate-induced nephritis. The irradiation increases catalase and decreases superoxide dismutase in kidney. The result suggests that low dose radiation reduced generation of hydroxide radical generation by reducing cellular hydroperoxide level. Single irradiation at 0.5 Gy at 12 week of age ameliorates incidence of type I diabetes in non-obese diabetic (NOD) mice through the suppression of inflammatory activity of splenocytes, and resultant apoptosis of β-cells in pancreas. The irradiation activities of superoxide dismutase and catalase, which coordinately diminish intracellular reactive oxygen species. Continuous irradiation at 0.70 mGy/hr from 10 week of age elongates life span, and suppresses alopecia in type II diabetesmice. The irradiation improved glucose clearance without affecting insulin-resistance, and increased pancreatic catalase activity. The results suggest that continuous low dose-rate irradiation protect

  2. Testing the individual effective dose hypothesis.

    Science.gov (United States)

    Vu, Hung T; Klaine, Stephen J

    2014-04-01

    The assumption of the individual effective dose is the basis for the probit method used for analyzing dose or concentration-response data. According to this assumption, each individual has a uniquely innate tolerance expressed as the individual effective dose (IED) or the smallest dose that is sufficient to kill the individual. An alternative to IED, stochasticity suggests that individuals do not have uniquely innate tolerance; deaths result from random processes occurring among similar individuals. Although the probit method has been used extensively in toxicology, the underlying assumption has not been tested rigorously. The goal of the present study was to test which assumption, IED or stochasticity, best explained the response of Daphnia magna exposed to multiple pulses of copper sulfate (CuSO4 ) over 24 d. Daphnia magna were exposed to subsequent age-dependent 24-h median lethal concentrations (LC50s) of copper (Cu). Age-dependent 24-h LC50 values and Cu depuration test were determined prior to the 24-d bioassay. The LC50 values were inversely related to organism age. The Cu depuration of D. magna did not depend on age or Cu concentration, and 5 d was sufficient recovery time. Daphnia magna were exposed to 4 24-h Cu exposures, and surviving organisms after each exposure were transferred to Cu-free culture media for recovery before the next exposure. Stochasticity appropriately explained the survival and reproduction response of D. magna exposed to Cu. PMID:24318469

  3. Cytogenetic measurements of the relative biological effectiveness of tritium

    International Nuclear Information System (INIS)

    Chromosome aberrations in peripheral blood lymphocytes, which are used to estimate radiation dose biologically, were induced by tritium 1.14 times as effectively as X-rays (95% confidence limits: 0.8 - 1.5). Chromosome translocations in spermatogonia, which are one component of genetic risk, were induced by tritium 1.21 times as effectively as X-rays (95% confidence limits: 0.8 -1.9). All experimental measurements were made in CBA/H mice injected with tritiated water or exposed to X-rays at a comparable dose rate

  4. The effect of radiation dose on mouse skeletal muscle remodeling

    International Nuclear Information System (INIS)

    The purpose of this study was to determine the effect of two clinically relevant radiation doses on the susceptibility of mouse skeletal muscle to remodeling. Alterations in muscle morphology and regulatory signaling were examined in tibialis anterior and gastrocnemius muscles after radiation doses that differed in total biological effective dose (BED). Female C57BL/6 (8-wk) mice were randomly assigned to non-irradiated control, four fractionated doses of 4 Gy (4x4 Gy; BED 37 Gy), or a single 16 Gy dose (16 Gy; BED 100 Gy). Mice were sacrificed 2 weeks after the initial radiation exposure. The 16 Gy, but not 4x4 Gy, decreased total muscle protein and RNA content. Related to muscle regeneration, both 16 Gy and 4x4 Gy increased the incidence of central nuclei containing myofibers, but only 16 Gy increased the extracellular matrix volume. However, only 4x4 Gy increased muscle 4-hydroxynonenal expression. While both 16 Gy and 4x4 Gy decreased IIB myofiber mean cross-sectional area (CSA), only 16 Gy decreased IIA myofiber CSA. 16 Gy increased the incidence of small diameter IIA and IIB myofibers, while 4x4 Gy only increased the incidence of small diameter IIB myofibers. Both treatments decreased the frequency and CSA of low succinate dehydrogenase activity (SDH) fibers. Only 16 Gy increased the incidence of small diameter myofibers having high SDH activity. Neither treatment altered muscle signaling related to protein turnover or oxidative metabolism. Collectively, these results demonstrate that radiation dose differentially affects muscle remodeling, and these effects appear to be related to fiber type and oxidative metabolism

  5. Ionizing radiation: effects of low doses

    International Nuclear Information System (INIS)

    This article deals with the important and delicate subject posed by the study of the action on Man's health of low doses of ionizing radiation. A number of fundamental notions whose knowledge is indispensable in order to avoid doubtful meanings or misunderstandings are noted in this article. Following the reminder of these notions, the characteristics of the various types of pathological effects of radiation are indicated, as well as how it is possible for effects which are named ''aleatory'' to be evaluated with care so as to limit risks at low doses. The reader will easily understand that this article has to be somewhat didactic - it seemed best to proceed by well defined stages and to clearly specify numerous concepts whose meanings are not always clearly defined when such problems are treated

  6. Effect of low-dose ionizing radiation on immune system in mice

    Energy Technology Data Exchange (ETDEWEB)

    Hoshi, Y.; Sakai, K. [Central Research Institute of Electric Power Industry, Tokyo (Japan)

    2002-07-01

    Low-dose irradiation induces a number of biological functions in mice. Nomura et al. have demonstrated that the low-dose irradiation elevates the level of antioxidants and gives suppressive effects on some chemically induced reactive oxygen species (ROS)-related disease models. We paid attention to this stimulated immunological function by low dose irradiation and started the study that by low dose irradiation and started the study that by low-dose rate irradiation. The enhancement of immune response in mice under various conditions will be discussed.

  7. Effect of low-dose ionizing radiation on immune system in mice

    International Nuclear Information System (INIS)

    Low-dose irradiation induces a number of biological functions in mice. Nomura et al. have demonstrated that the low-dose irradiation elevates the level of antioxidants and gives suppressive effects on some chemically induced reactive oxygen species (ROS)-related disease models. We paid attention to this stimulated immunological function by low dose irradiation and started the study that by low dose irradiation and started the study that by low-dose rate irradiation. The enhancement of immune response in mice under various conditions will be discussed

  8. Dose and Dose-Rate Effectiveness Factor (DDREF); Der Dosis- und Dosisleistungs-Effektivitaetsfaktor (DDREF)

    Energy Technology Data Exchange (ETDEWEB)

    Breckow, Joachim [Fachhochschule Giessen-Friedberg, Giessen (Germany). Inst. fuer Medizinische Physik und Strahlenschutz

    2016-08-01

    For practical radiation protection purposes it is supposed that stochastic radiation effects a determined by a proportional dose relation (LNT). Radiobiological and radiation epidemiological studies indicated that in the low dose range a dependence on dose rates might exist. This would trigger an overestimation of radiation risks based on the LNT model. OCRP had recommended a concept to combine all effects in a single factor DDREF (dose and dose-Rate effectiveness factor). There is still too low information on cellular mechanisms of low dose irradiation including possible repair and other processes. The Strahlenschutzkommission cannot identify a sufficient scientific justification for DDREF and recommends an adaption to the actual state of science.

  9. Effective dose to radon considering people's activities

    International Nuclear Information System (INIS)

    The tidal volume was estimated for evaluating the effective dose due to radon concentration in the atmosphere. In this study regional population was separated to vocation and non-vocation. The occupancy time and the breathing rate for both vocation and non-vocation groups were estimated, and the annual tidal volume for both groups were calculated. Human actions were separated to 18 activities in the process for estimating the breathing rate. It was clear that the breathing rate depended on human activity and that the human activity changed with its age, so the breathing rate varied with age. Finally the effective doses due to radon and radon progeny indoors and outdoors were evaluated. The maximum annual effective dose was estimated to be 1.2 mSv, minimum 0.2 mSv, and mean 0.51 mSv for vocation. For non-vocation, the male maximum value 0.43 mSv was obtained at the 16 age and the minimum 0.12 mSv at the 70 age, whereas female maximum 0.26 mSv was obtained at the 12 age and the minimum 0.11 mSv at the 70 age. In addition in this study objective areas are Aichi, Gifu, and Mie prefectures for vocation and only Aichi prefecture for non-vocation. (author)

  10. Biological effects of deuterium - depleted water

    International Nuclear Information System (INIS)

    Deuterium-depleted water (DDW) is represented by water that has an isotopic content smaller than 145 ppm D/(D + H). DDW production technique consists in the separation of deuterium from water by a continuous distillation process under pressure of about 133.3 mbar. The water used as raw material has a isotopic content of 145 ppm D/(D + H) and can be demineralized water, distillated water or condensed-steam. DDW results as a distillate with an isotopic deuterium content of 15-80 ppm, depending on the level we want to achieve. Beginning with 1996 the Institute of Cryogenics and Isotopic Technologies, DDW producer, co-operated with Romanian specialized institutes for studying the biological effects of DDW. The role of naturally occurring D in living organisms was examined by using DDW instead of natural water. These investigations led to the following conclusions: - DDW caused a tendency towards the increase of the basal tone, accompanied by the intensification of the vasoconstrictor effects of phenylefrine, noradrenaline and angiotensin; the increase of the basal tone and vascular reactivity produced by the DDW persists after the removal of the vascular endothelium; - Animals treated with DDW showed an increase of the resistance both to sublethal and lethal gamma radiation doses, suggesting a radioprotective action by the stimulation of non-specific immune defense mechanisms; - DDW stimulates immuno-defense reactions represented by the opsonic, bactericidal and phagocyte capacity of the immune system together with an increase in the number of poly-morphonuclear neutrophils; - Investigations regarding artificial reproduction of fish with DDW fecundated solutions confirmed favorable influence in embryo growth stage and resistance and following growth stages; - It was studied germination, growth and quantitative character variability in plants; one can remark the favorable influence of DDW on biological processes in plants in various ontogenetic stages. (authors)

  11. Biological dose estimation and cytogenetic follow-up observation for a patient with subacute radiation sickness

    International Nuclear Information System (INIS)

    Objective: To conduct the biological dose estimation and cytogenetic observation for the patient with subacute radiation sickness in a 192Ir source radiation accident. Methods: Conventional chromosome aberration analysis and micronucleus assay in peripheral blood lymphocytes were performed, and the accumulated dose was estimated by G function according to the frequencies of dicentric and ring on the patient. Results: The estimated doses were close to those values estimated by physical method, in accordance with the appearance expression of clinical symptoms. At 1.5 and 2.5 years after the accident, clear decrease were observed in dicentric chromosomes but not in acentric fragments and micronuclei. Conclusions: The estimation of accumulated dose by G function can reflect the real degree of radiation damage. The decreased rate of chromosome aberration and micronucleus in the patient with subacute radiation sickness might be slower than those with acute radiation sickness. (authors)

  12. Health Effects of Exposure to Low Dose of Radiation

    International Nuclear Information System (INIS)

    Human beings are exposed to natural radiation from external sources include radionuclides in the earth and cosmic radiation, and by internal radiation from radionuclides, mainly uranium and thorium series, incorporated into the body. Living systems have adapted to the natural levels of radiation and radioactivity. But some industrial practices involving natural resources enhance these radionuclides to a degree that they may pose risk to humans and the environment if they are not controlled. Biological effects of ionizing radiation are the outcomes of physical and chemical processes that occur immediately after the exposure, then followed by biological process in the body. These processes will involve successive changes in the molecular, cellular, tissue and whole organism levels. Any dose of radiation, no matter how small, may produce health effects since even a single ionizing event can result in DNA damage. The damage to DNA in the nucleus is considered to be the main initiating event by which radiation causes damage to cells that results in the development of cancer and hereditary disease. It has also been indicated that cytogenetic damage can occur in cells that receive no direct radiation exposure, known as bystander effects. This paper reviews health risks of low dose radiation exposure to human body causing stochastic effects, i.e. cancer induction in somatic cells and hereditary disease in genetic cells. (author)

  13. Relation between teeth-dose and effective dose for external photon exposure

    Energy Technology Data Exchange (ETDEWEB)

    Takahashi, F.; Yamaguchi, Y. [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Iwasaki, M.; Miyazawa, C. [School of Dentistry, Ohu Univ., Koriyama, Fukushima (Japan); Hamada, T. [Nuclear Safety Research Association, Tokyo (Japan)

    2000-05-01

    Electron spin resonance (ESR) dosimetry using tooth enamel has been applied to individual dose assessments for atomic-bomb survivors and residents affected by the Chernobyl accident. This method is based on the assumption of the linear relation between intensity of ESR signal induced by radicals in the tooth enamel and the absorbed dose. The individual dose is usually estimated in terms of effective dose in radiation protection practices. In this context, it is important to obtain a quantitative relationship between the effective dose and the absorbed dose in teeth estimated by the ESR dosimetry. In the present work, the relationship between absorbed dose in teeth and effective dose was analyzed to enable to predict the individual dose and effective dose by the ESR dosimetry using tooth enamel for external photon exposure. Monte Carlo calculations using the EGS4 code were performed to study angular and energy dependence of the teeth-dose and effective dose for photon incidences. All the calculated teeth-doses were quantitatively related to the effective dose. An experiment was also carried out to verify the calculated results, using a tissue equivalent head phantom with a full set of human teeth. The calculated and measured results were compared with those by the ESR dosimetry for a {sup 60}Co source. It was found from our studies that the teeth-dose depends more significantly on photon energy than the effective dose and energy spectral distribution should be considered for a precise dose assessment. The results also suggested that the distribution of the teeth-dose in the mouth could give useful information of source to human configuration. (author)

  14. Relation between teeth-dose and effective dose for external photon exposure

    International Nuclear Information System (INIS)

    Electron spin resonance (ESR) dosimetry using tooth enamel has been applied to individual dose assessments for atomic-bomb survivors and residents affected by the Chernobyl accident. This method is based on the assumption of the linear relation between intensity of ESR signal induced by radicals in the tooth enamel and the absorbed dose. The individual dose is usually estimated in terms of effective dose in radiation protection practices. In this context, it is important to obtain a quantitative relationship between the effective dose and the absorbed dose in teeth estimated by the ESR dosimetry. In the present work, the relationship between absorbed dose in teeth and effective dose was analyzed to enable to predict the individual dose and effective dose by the ESR dosimetry using tooth enamel for external photon exposure. Monte Carlo calculations using the EGS4 code were performed to study angular and energy dependence of the teeth-dose and effective dose for photon incidences. All the calculated teeth-doses were quantitatively related to the effective dose. An experiment was also carried out to verify the calculated results, using a tissue equivalent head phantom with a full set of human teeth. The calculated and measured results were compared with those by the ESR dosimetry for a 60Co source. It was found from our studies that the teeth-dose depends more significantly on photon energy than the effective dose and energy spectral distribution should be considered for a precise dose assessment. The results also suggested that the distribution of the teeth-dose in the mouth could give useful information of source to human configuration. (author)

  15. Physical and biological factors determining the effective proton range

    Energy Technology Data Exchange (ETDEWEB)

    Grün, Rebecca [Department of Biophysics, GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt 64291 (Germany); Institute of Medical Physics and Radiation Protection, University of Applied Sciences Gießen, Gießen 35390 (Germany); Medical Faculty of Philipps-University Marburg, Marburg 35032 (Germany); Friedrich, Thomas; Krämer, Michael; Scholz, Michael [Department of Biophysics, GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt 64291 (Germany); Zink, Klemens [Institute of Medical Physics and Radiation Protection, University of Applied Sciences Gießen, Gießen 35390, Germany and Department of Radiotherapy and Radiation Oncology, University Medical Center Giessen and Marburg, Marburg 35043 (Germany); Durante, Marco [Department of Biophysics, GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt 64291, Germany and Department of Condensed Matter Physics, Darmstadt University of Technology, Darmstadt 64289 (Germany); Engenhart-Cabillic, Rita [Medical Faculty of Philipps-University Marburg, Marburg 35032, Germany and Department of Radiotherapy and Radiation Oncology, University Medical Center Giessen and Marburg, Marburg 35043 (Germany)

    2013-11-15

    Purpose: Proton radiotherapy is rapidly becoming a standard treatment option for cancer. However, even though experimental data show an increase of the relative biological effectiveness (RBE) with depth, particularly at the distal end of the treatment field, a generic RBE of 1.1 is currently used in proton radiotherapy. This discrepancy might affect the effective penetration depth of the proton beam and thus the dose to the surrounding tissue and organs at risk. The purpose of this study was thus to analyze the impact of a tissue and dose dependent RBE of protons on the effective range of the proton beam in comparison to the range based on a generic RBE of 1.1.Methods: Factors influencing the biologically effective proton range were systematically analyzed by means of treatment planning studies using the Local Effect Model (LEM IV) and the treatment planning software TRiP98. Special emphasis was put on the comparison of passive and active range modulation techniques.Results: Beam energy, tissue type, and dose level significantly affected the biological extension of the treatment field at the distal edge. Up to 4 mm increased penetration depth as compared to the depth based on a constant RBE of 1.1. The extension of the biologically effective range strongly depends on the initial proton energy used for the most distal layer of the field and correlates with the width of the distal penumbra. Thus, the range extension, in general, was more pronounced for passive as compared to active range modulation systems, whereas the maximum RBE was higher for active systems.Conclusions: The analysis showed that the physical characteristics of the proton beam in terms of the width of the distal penumbra have a great impact on the RBE gradient and thus also the biologically effective penetration depth of the beam.

  16. The late biological effects of ionizing radiation

    International Nuclear Information System (INIS)

    Full text: The principal objective of the symposium was to review the current status of understanding of the late biological effects of ionizing radiation from external and internal sources. A second objective was to critically evaluate information obtained from epidemiological studies of human population groups as well as from animal experimentation in order to provide a solid scientific basis upon which problems of current concern, such as radiation protection standards and risk-benefit analysis, could be deliberated. Eighty-one papers were presented in 10 sessions which covered epidemiological studies of late effects in human populations exposed to internal and/or external ionizing radiation; quantitative and qualitative data from animal experimentation of late effects; methodological problems and modern approaches; factors influencing susceptibility or expression of late radiation injury; comparative evaluation of late effects induced by radiation and other environmental pollutants, and problems of risk assessment. In addition, there were two evening sessions for free discussion of problems of interpreting animal data, and of the epidemiological studies of occupationally exposed populations. Reports on atomic bomb survivors showed that these epidemiological studies are providing dependable data, such as dose-related excess infant mortality. The reports also revealed the need for consensus in the method employed in the interpretation of data. That was also the case with studies on occupationally exposed populations at Hanford plant, where disparate results were presented on radiation-induced neoplasia among radiation workers. These data are, however, considered not so significant in relative terms when compared to risks involved in other industries. It was recommended that national registry systems for the dosimetry and medical records of radiation workers be established and co-ordinated internationally in order to facilitate reliable epidemiological

  17. Effective dose for radon progeny in Japan

    International Nuclear Information System (INIS)

    We estimated the effective dose for radon progeny in the Japanese population. The value was calculated with a modified UNSCEAR equation taking the following terms into consideration; radon concentration, radon equilibrium factor, occupancy factor or annual tidal volume, activity-energy conversion coefficient and dose conversion coefficient. The following figures were used in the calculation; a radon concentration of 15.5 (7 - 27) Bq/m3 for indoors and 5.0 (2.5 - 10) Bq/m3 outdoors; an equilibrium factors of 0.45 (0.35 - 0.57) for indoors and 0.70 (0.50 - 0.90) outdoors; an occupancy factor of 0.87 for indoors and 0.13 outdoors for males, and 0.91 indoors and 0.09 outdoors for females; an annual tidal volume of 7,000 (6,350 - 7,900) m3 for males and 6,600 (6,100 - 7,550) m3 for females. The annual tidal volume was obtained the product of tidal volume and occupancy time, which were estimated in Japan and from surveys on Japanese life-style. The effective annual doses for radon were estimated to be 0.55 mSv for males, 0.49 mSv for females and 0.52 mSv for the mean of both sexes. These were about 40% of the value shown in the 1993 UNSCEAR Report. The dose range due to ranges of the factor was -75 - +175% of the representative value. (author)

  18. Biological effectiveness of antiproton annihilation

    DEFF Research Database (Denmark)

    Holzscheiter, M.H.; Agazaryan, N.; Bassler, Niels;

    2004-01-01

    We describe an experiment designed to determine whether or not the densely ionizing particles emanating from the annihilation of antiprotons produce an increase in ‘‘biological dose’’ in the vicinity of the narrow Bragg peak for antiprotons compared to protons. This experiment is the first direct...

  19. Patient Dosimetry in Arteriography of the Lower Limbs. Part II: Dose Conversion Coefficients, Organ Doses and Effective Dose

    International Nuclear Information System (INIS)

    X ray projection data (see Part I) and GSF phantoms ADAM and EVA were used as input for the GSF Monte Carlo transport code to calculate hitherto unavailable dose conversion coefficients (DCCs) for common projections in arteriography of the lower limbs. These DCCs served to estimate organ equivalent doses and effective dose in a study of 455 patients. The effective dose caused by percutaneous needle puncture arteriography of one leg was on average 1 mSv, by Seldinger catherisation for arteriography of both legs 4 mSv, and by intravenous digital subtraction arteriography (DSA) 5 mSv. For needle puncture and Seldinger arteriography the effective dose attributable to fluoroscopy was about 50% for male and 60% for female patients. The contribution of DSA was between 15 and 35%, that of cut films between 17 to 28%, depending on gender and procedure. The effective dose in intravenous arteriography was mainly due to DSA (91-93%). (author)

  20. Biological effects of high LET radiations

    Energy Technology Data Exchange (ETDEWEB)

    Watanabe, Masami [Nagasaki Univ. (Japan). Faculty of Pharmaceutical Sciences

    1997-03-01

    Biological effect of radiation is different by a kind of it greatly. Heavy ions were generally more effective in cell inactivation, chromosome aberration induction, mutation induction and neoplastic cell transformation induction than {gamma}-rays in SHE cells. (author)

  1. Arsenic, mode of action at biologically plausible low doses: What are the implications for low dose cancer risk?

    International Nuclear Information System (INIS)

    Arsenic is an established human carcinogen. However, there has been much controversy about the shape of the arsenic response curve, particularly at low doses. This controversy has been exacerbated by the fact that the mechanism(s) of arsenic carcinogenesis are still unclear and because there are few satisfactory animal models for arsenic-induced carcinogenesis. Recent epidemiological studies have shown that the relative risk for cancer among populations exposed to ≤60 ppb As in their drinking water is often lower than the risk for the unexposed control population. We have found that treatment of human keratinocyte and fibroblast cells with 0.1 to 1 μM arsenite (AsIII) also produces a low dose protective effect against oxidative stress and DNA damage. This response includes increased transcription, protein levels and enzyme activity of several base excision repair genes, including DNA polymerase β and DNA ligase I. At higher concentrations (> 10 μM), As induces down-regulation of DNA repair, oxidative DNA damage and apoptosis. This low dose adaptive (protective) response by a toxic agent is known as hormesis and is characteristic of many agents that induce oxidative stress. A mechanistic model for arsenic carcinogenesis based on these data would predict that the low dose risk for carcinogenesis should be sub-linear. The threshold dose where toxicity outweighs protection is hard to predict based on in vitro dose response data, but might be estimated if one could determine the form (metabolite) and concentration of arsenic responsible for changes in gene regulation in the target tissues

  2. Report of task group on the biological basis for dose limitation in the skin

    International Nuclear Information System (INIS)

    Researchers have drawn attention to what they consider inconsistencies in the manner in which ICRP have considered skin in relation to the effective dose equivalent. They urge that the dose to the skin should be considered routinely for inclusion in the effective dose equivalent in the context of protection of individuals and population groups. They note that even with a weighting factor of only 0.01 that the dose to the skin can be a significant contributor to the effective dose equivalent including skin for practical exposure conditions. In the case of many exposures the risk to the skin can be ignored but exposure in an uniformly contaminated cloud that might occur with 85Kr the dose to the skin could contribute 60% of the stochastic risk if included in the effective dose equivalent with a WT of 0.01. Through the years and even today the same questions about radiation effects in the skin and dosimetry keep being asked. This report collates the available data and current understanding of radiation effects on the skin, and may make it possible to estimate risks more accurately and to improve the approach to characterizing skin irradiations. 294 refs., 29 figs

  3. Effect of dose ascertainment errors on observed risk

    International Nuclear Information System (INIS)

    Inaccuracies in dose assignments can lead to misclassification in epidemiological studies. The extent of this misclassification is examined for different error functions, classification intervals, and actual dose distributions. The error function model is one which results in a truncated lognormal distribution of the assigned dose for each actual dose. The error function may vary as the actual dose changes. The effect of misclassification on the conclusions about dose effect relationships is examined for the linear and quadratic dose effect models. 10 references, 9 figures, 8 tables

  4. Biologically motivated tumor-models used for risk estimates at low doses of radiation

    International Nuclear Information System (INIS)

    Biologically motivated tumour models are necessary for estimating the radiation risk at low doses, as epidemiological studies cannot give significant results for sufficiently small risks as a matter of principle. The tumour models combine knowledge about the mechanisms of tumour development with epidemiological data and results of animal experiments. The are usefuls for testing hypothesis on radiation carcinogenesis. In the framework of EU-projects European partners work on the difficult task of quantifying the relevant biological parameters, and the radiation risk at low doses. Various data sets are described well by assuming an initiating and a promoting action of radiation. As an example a new analysis of radon-induced lung tumours in the Colorado plateau miners is discussed. The estimated lifetime relative risk extrapolated to exposures as they hold in indoor situations is substantially lower than estimated in the BEIR VI report. (orig.)

  5. Dose-Volume Effects in Rat Thoracolumbar Spinal Cord: The Effects of Nonuniform Dose Distribution

    International Nuclear Information System (INIS)

    Purpose: To investigate dose-volume effects in rat spinal cord irradiated with nonuniform dose distributions and to assess regional differences in radiosensitivity. Methods and Materials: A total of 106 rats divided into three groups were irradiated with 192Ir γ-rays at a high dose rate. The groups were irradiated with one, two, or six catheters distributed around the thoracolumbar spinal cord to create different dose distributions. After irradiation, the animals were tested for motor function for 9 months. The response was defined as motor dysfunction and WM or nerve root necrosis. Dose-response data were analyzed with a probit analysis as function of the dose level at a percentage of the volume (D%) and with different normal tissue complication probability models. Additionally, the histologic responses of the individual dose voxels were analyzed after registration with the histologic sections. Results: The probit analysis at D24 (24% of the volume) gave the best fit results. In addition, the Lyman Kutcher Burman model and the relative seriality model showed acceptable fits, with volume parameters of 0.17 and 0.53, respectively. The histology-based analysis revealed a lower radiosensitivity for the dorsal (50% isoeffective dose [ED50] = 32.3) and lateral WM (ED50 = 33.7 Gy) compared with the dorsal (ED50 = 25.9 Gy) and ventral nerve roots (ED50 = 24.1 Gy). Conclusions: For this nonuniform irradiation, the spinal cord did not show typical serial behavior. No migration terms were needed for an acceptable fit of the dose-response curves. A higher radiosensitivity for the lumbar nerve roots than for the thoracic WM was found

  6. Immunological effects of low dose radiation. Absent or minor effects of Chernobyl fallout in Norway?

    Energy Technology Data Exchange (ETDEWEB)

    Reitan, J.B.; Bergan, T.D.; Strand, P. [Statens Straalevern, Oesteraas (Norway); Melbye, O.J. [Rikshospitalet, Oslo (Norway)

    1998-01-01

    In this pilot study of those Norwegian individuals most heavily exposed to the Chernobyl Fallout, immunological parameters generally stayed within normal limits. However, some parameter, apparently within the assumed normal range did, in fact correlate to the estimated individual dose as assessed by wholebody counting of radiocaesium content. The small possible effects revealed in this study may represent real biological effects, but do not necessarily represent a health detriment. 43 refs., 4 figs., 6 tabs.

  7. Immunological effects of low dose radiation. Absent or minor effects of Chernobyl fallout in Norway?

    International Nuclear Information System (INIS)

    In this pilot study of those Norwegian individuals most heavily exposed to the Chernobyl Fallout, immunological parameters generally stayed within normal limits. However, some parameter, apparently within the assumed normal range did, in fact correlate to the estimated individual dose as assessed by wholebody counting of radiocaesium content. The small possible effects revealed in this study may represent real biological effects, but do not necessarily represent a health detriment. 43 refs., 4 figs., 6 tabs

  8. Definition of the dose(tempo)-distribution in the biological irradiation-facility of the RIVM

    International Nuclear Information System (INIS)

    The RIVM biological irradiation facility (BBF) for the irradiation of biological samples and small animals is a self shielded device and can be safely operated in an existing laboratory environment. There are two 137Cs sources (15TBq) in a bilateral geometry to give maximum dose uniformity. The easily accessible irradiation chamber is housed in a rotating lead shielding. The dosimetry of BBF was performed by the Dosimetry Section of the RIVM. Experiments were made to determine the absorbed dose in plastic tubes filled with water and the dose distribution over the tube-holder. Separate experiments were made to determine the absorbed dose during the rotation of the irradiation chamber and to check the irradiation timer. For the experiments LiF:Mg,Ti (TLD-100) extruded ribbons were used. The TLDs were calibrated in a collimated beam of 137Cs gamma rays. The determination of the absorbed dose in water was based on a users biological irradiation set up. The TLDs were individually sealed in thin plastic foil and put in plastic tubes filled for 1/3 with water. The tubes were vertically placed in the tube-holder and placed in the centre of the irradiation chamber. The results show that the absorbed dose in water (determined on January 1, 1990) is equal to 0.97 Gy/timer-unit, with a total uncertainty of 7 percent (1σ). During the rotation of the irradiation chamber the absorbed dose (determined on January 1, 1990) is equal to 0.38 Gy, with a total uncertainty of 15 percent (1σ). The variation of the dose distribution was determined at 15 different measurement points distributed over the tube-holder. The dosis in the measurement point in the centre of the tube-holder was taken as reference value. The maximum observed deviation over the other 14 measurement points amounts to -16 percent of it. The BBF-timer was checked against a special timer. The results indicate that within a range from 2-11 'timer-units' no differences are present. (author). 6 refs.; 6 figs.; 3 fotos; 11

  9. Activation of chemical biological defense mechanisms and alleviation of in vivo oxidation injury by low dose radiation

    International Nuclear Information System (INIS)

    We clarified that adequate oxygen stress induced by low dose radiation activates not only chemical biological protective function, such as induction of the synthesis of superoxide dismutase (SOD), glutathione peroxidase (GPX) and heat shock protein 70 (HSP70), but also the biomembrane function, such as enhanced membrane fluidity and ATPase activity. It is possible that activation of these mechanisms alleviates in vivo oxidation injuries resulting in alleviation of pathologic condition, such as ferric-nitrilotriacetate (Fe3+-NTA) or CCl4-induced liver damage, 1-methyl-4-phenyl 1,2,3,6-tetrahydro-pyridine (MPTP)-induced brain damage and diabetes mellitus. Namely, in contrast to the toxic effects of high dose irradiation, adequate activation of the functions of the living body by low dose radiation or inhalation of an appropriate amount of radon can contribute to suppressing aging and to preventing or reducing active oxygen species related diseases which are thought to involve peroxidation and have been regarded as the diseases for which radon spring water is an effective treatment. In future, clarification in detail of the mechanisms of these phenomena is required to understand the effects of low dose radiation on the functions of the living body, including adaptive response. (author)

  10. Alternative Physical Quality Parameters Influences Effectiveness of Lower Doses Ionizing Radiation

    Science.gov (United States)

    Yousif, Abubaker Ali; Bahari, Ismail Bin; Yasir, Muhamad Samudi

    2011-03-01

    It has been proved in many studied that the absorbed dose is not good physical quality parameter to quantify the radiation effects at lower doses. However relative biological effect (RBE) is still used as a major parameter of radiation effectiveness. Whereas linear energy transfer (LET) is inadequate physical parameter, therefore the weaknesses in using RBE-LET system for radiation protection have been investigated. Secondary data of V79 has reanalyzed to help complement the inadequacy current method in assessing cell inactivation at lower doses. Results of analysis show that the effectiveness of densely ionizing radiation is better quantified using mean free path (λ).

  11. Evaluation of effective dose equivalent for personal dosimetry

    International Nuclear Information System (INIS)

    The concept of effective dose equivalent was recommended as a primary limit in the ICRP publication 26. And dose equivalent index and ALI were introduced as the secondary limits for external and internal dose limitation system respectively. The evaluation method of effective dose equivalent and its application to a routinal dosimetry were studied as the followings, 1). For the external dose evaluation, the measuring method of 1 cm deep dose equivalent by a TL-dosemeter using Li2B4O7(Cu) element is shown. Also the relationship between 1 cm deep dose equivalent and effective dose equivalent is disscused. 2). For the internal dose evaluation, the monitering methods and the dose evaluation method are shown for the case of 239Pu or 137Cs intake. (author)

  12. Dose reconstruction starting from the pre-dose effect of quartz: combined procedure of additive dose and multiple activation

    International Nuclear Information System (INIS)

    The pre-dose effect of the 110 C thermoluminescence (Tl) peak of quartz gives rise to the use of a sensitive technique to estimate of low-level doses under retrospective conditions. However, one can appreciate how aliquots of quartz, from the same mineral fraction, display different sensitivities. In this sense, we herein report on a new measurement protocol based on the aforementioned pre-dose effect. Such procedure includes additive dose and multiple activation steps allows to determine simultaneously the sensitivity changes induced by the thermal activation and the Tl dose dependence. This behaviour let calculate the field accrued dose by interpolation thus permitting an increase of both precision and accuracy. (Author)

  13. Comments on 'Standard effective doses for proliferative tumours'

    International Nuclear Information System (INIS)

    general remarks about calculating standard effective doses when proliferation is involved. We feel that such clarification is necessary since biological endpoints are now considered for incorporation into treatment planning programs. (U.K.). Letter-to-the-editor

  14. Contribution of the modulation of intensity and the optimization to deliver a dose adapted to the biological heterogeneities

    International Nuclear Information System (INIS)

    The recent progress in functional imaging by Positron Emission Tomography (TEP) opens new perspectives in the delineation of target volumes in radiotherapy. The functional data is major; we can intend to adapt the irradiation doses on the tumor activity (TA) and to perform a dose escalation. Our objectives were (i) to characterize the TEP threshold, by quantifying the uncertainties of the target volume contour according to the lesion size and the threshold contour level, (ii) to set up the geometry suited to perform a high-precision irradiation based on the TA, (iii) to estimate the dosimetric impact of this new protocol and (iv) to verify that dosimetry is perfectly distributed. Three original phantoms were specially created to satisfy the constraints met, as well as two virtual phantoms containing 3 dose levels (dose level 3 = TA). Our results showed the importance of the effect threshold-volume on the planning in radiotherapy. To use this irradiation method, the diameter of 1 cm for the third level was able to be reached. A dose escalation of 20 Gy was possible between the second (70 Gy) and the third level (90 Gy). The dosimetric impact estimated on two real cases was suitable - increase of COIN (conformal index) from 0.6 to 0.8 and decrease of NTCP (normal tissue complication probability) of a factor 5 -. In absolute and relative dosimetry, the clinical tolerances were respected. So all the treatment process, going from the diagnosis with the TEP to reveal the TA, to the patient treatment made beforehand on phantom, and going through the ballistic and the dose calculation, was estimated and validated according to our objective to adapt the irradiation to the biological heterogeneities. However such high doses should be carefully estimated before being prescribed clinically and progress is also expected in imaging, because the minimal size which we can irradiate is on the limit of the resolution TEP. (author)

  15. Reconstruction of biologically equivalent dose distribution on CT-image from measured physical dose distribution of therapeutic beam in water phantom

    International Nuclear Information System (INIS)

    From the standpoint of quality assurance in radiotherapy, it is very important to compare the dose distributions realized by an irradiation system with the distribution planned by a treatment planning system. To compare the two dose distributions, it is necessary to convert the dose distributions on CT images to distributions in a water phantom or convert the measured dose distributions to distributions on CT images. Especially in heavy-ion radiotherapy, it is reasonable to show the biologically equivalent dose distribution on the CT images. We developed tools for the visualization and comparison of these distributions in order to check the therapeutic beam for each patient at the National Institute of Radiological Sciences (NIRS). To estimate the distribution in a patient, the dose is derived from the measurement by mapping it on a CT-image. Fitting the depth-dose curve to the calculated SOBP curve also gives biologically equivalent dose distributions in the case of a carbon beam. Once calculated, dose distribution information can be easily handled to make a comparison with the planned distribution and display it on a grey-scale CT-image. Quantitative comparisons of dose distributions can be made with anatomical information, which also gives a verification of the irradiation system in a very straightforward way. (author)

  16. Hafnium oxide nanoparticles: toward an in vitro predictive biological effect?

    International Nuclear Information System (INIS)

    Hafnium oxide, NBTXR3 nanoparticles were designed for high dose energy deposition within cancer cells when exposed to ionizing radiation. The purpose of this study was to assess the possibility of predicting in vitro the biological effect of NBTXR3 nanoparticles when exposed to ionizing radiation. Cellular uptake of NBTXR3 nanoparticles was assessed in a panel of human cancer cell lines (radioresistant and radiosensitive) by transmission electron microscopy. The radioenhancement of NBTXR3 nanoparticles was measured by the clonogenic survival assay. NBTXR3 nanoparticles were taken up by cells in a concentration dependent manner, forming clusters in the cytoplasm. Differential nanoparticle uptake was observed between epithelial and mesenchymal or glioblastoma cell lines. The dose enhancement factor increased with increase NBTXR3 nanoparticle concentration and radiation dose. Beyond a minimum number of clusters per cell, the radioenhancement of NBTXR3 nanoparticles could be estimated from the radiation dose delivered and the radiosensitivity of the cancer cell lines. Our preliminary results suggest a predictable in vitro biological effect of NBTXR3 nanoparticles exposed to ionizing radiation

  17. Determination of the effective dose equivalent in gynecologic radium therapy

    International Nuclear Information System (INIS)

    In this study, the authors describe how to determine the effective dose equivalent absorbed by occupationally exposed persons during a gynecologic radium therapy. The observed irradiation conditions of the physician and the medical staff are approximated by a standard geometry, for which conversion factors between the measured personal dose, the effective dose equivalent and different organ doses, respectively, are calculated. The results are job-specific conversion factors between dose to a personal dosimeter and the effective dose equivalent for the occupationally exposed persons involved. According to the individual tasks, these factors are between 0.59 and 1.13. (orig.)

  18. Nicotine dose-concentration relationship and pregnancy outcomes in rat: Biologic plausibility and implications for future research

    International Nuclear Information System (INIS)

    Cigarette smoke (CS) exposure during pregnancy can lead to profound adverse effects on fetal development. Although CS contains several thousand chemicals, nicotine has been widely used as its surrogate as well as in its own right as a neuroteratogen. The justification for the route and dose of nicotine administration is largely based on inferential data suggesting that nicotine 6 mg/kg/day infused continuously via osmotic mini pumps (OMP) would mimic maternal CS exposure. We provide evidence that 6 mg/kg/day nicotine dose as commonly administered to pregnant rats leads to plasma nicotine concentrations that are 3-10-fold higher than those observed in moderate to heavy smokers and pregnant mothers, respectively. Furthermore, the cumulative daily nicotine dose exceeds by several hundred fold the amount consumed by human heavy smokers. Our study does not support the widely accepted notion that regardless of the nicotine dose, a linear nicotine dose-concentration relationship exists in a steady-state OMP model. We also show that total nicotine clearance increases with advancing pregnancy but no significant change is observed between the 2nd and 3rd trimester. Furthermore, nicotine infusion even at this extremely high dose has little effect on a number of maternal and fetal biologic variables and pregnancy outcome suggesting that CS constituents other than nicotine mediate the fetal growth restriction in infants born to smoking mothers. Our current study has major implications for translational research in developmental toxicology and pharmacotherapy using nicotine replacement treatment as an aid to cessation of cigarette smoking in pregnant mothers

  19. Attributability of Health Effects at Low Radiation Doses

    International Nuclear Information System (INIS)

    the assumption that the relationship between the number of people being exposed and their doses is robust enough to make epidemiological attestability feasible (Strictly, the population would also need to be identical to those populations studied epidemiologically). - Conversely, at the individual level, stochastic health effects at low doses are, at this time of biological understanding, unfeasible to be credited, assigned and imputed and consequently ascribed to a specific exposure situation; - However, if attributability is taken to be a stochastic notion, then a conditional probability of causation can be theoretically assigned (following Bayes' theorem and using available scientific information). This stochastic attributability, nevertheless, will not be attestable. - Therefore, while individual health effects can under certain theoretical assumptions be stochastically attributable, they can not be subjected to an attestable attributability. - As a result, presently individual health effects can not be deterministically attributable to radiation exposure situations delivering low radiation doses and, thus, they may not be deemed attributable in codified legal systems.(authors)

  20. Attributability of health effects at low radiation doses

    International Nuclear Information System (INIS)

    assumption that the relationship between the number of people being exposed and their doses is robust enough to make epidemiological attestability feasible (Strictly, the population would also need to be identical to those populations studied epidemiologically). - Conversely, at the individual level, stochastic health effects at low doses are, at this time of biological understanding, unfeasible to be credited, assigned and imputed and consequently ascribed to a specific exposure situation; - However, if attributability is taken to be a stochastic notion, then a conditional probability of causation can be theoretically assigned (following Bayes' theorem and using available scientific information). This stochastic attributability, nevertheless, will not be attestable. - Therefore, while individual health effects can under certain theoretical assumptions be stochastically attributable, they can not be subjected to an attestable attributability. - As a result, presently individual health effects can not be deterministically attributable to radiation exposure situations delivering low radiation doses and, thus, they may not be deemed attributable in codified legal systems. (author)

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1999-07-01

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

  2. BIOLOGICAL EFFECTS OF PULSED SHORT WAVE TREATMENT. AN EXPERIMENTAL STUDY

    Directory of Open Access Journals (Sweden)

    Dogaru Gabriela

    2015-02-01

    Full Text Available Pulsed short waves are short electromagnetic waves emitted as intermittent trains with a fixed duration, separated by free intervals of variable duration. The biological effects of pulsed short waves could be explained according to most of the authors by an activation of cellular enzymatic reactions, a stimulation of energy metabolism, a stimulation of liver function, of adrenal gland function and of the reticulocyte system, changes in cell permeability, by an increase of peripheral blood flow through the enhancement of local vascularization. This research aimed to investigate the biological effects of exposure to pulsed short waves at different doses on the adrenal glands of experimental animals, by structural and ultrastructural studies. The study included 35 animals assigned to 4 groups. Group I included 10 experimental animals exposed to radiation at a dose of 1/80 impulses/sec, group II, 10 animals exposed to a dose of 4/400 impulses/sec, group III, 10 animals exposed to a dose of 6/600 impulses/sec, for 10 min/day, and the control group consisted of 5 unexposed animals. Structural and ultrastructural changes of adrenal glands induced by the dose of 4/400 impulses/sec, compared to the unexposed control group and the dose of 1/80 impulses/sec, include an intensification of protein synthesis processes, an enhancement of energy metabolism in providing the energy required for an increased production of hormones, an intensification of collagen fiber synthesis processes in the capsule, necessary for healing. It was demonstrated that this dose induced an intensification of hormone synthesis and secretion, a stimulation of adrenal function. At the dose of 6/600 cycles/sec, a slight diminution of hormone synthesis and secretion activity was found, which was not below the limits existing in the unexposed control group, but was comparable to group II. This dose is probably too strong for experimental animals, inducing them a state of stress. The

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

    International Nuclear Information System (INIS)

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2009-07-01

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

  5. Biological Effects of Neutron and Proton Irradiations. Vol. I. Proceedings of the Symposium on Biological Effects of Neutron Irradiations

    International Nuclear Information System (INIS)

    During recent years the interest in biological effects caused by neutrons has been increasing steadily as a result of the rapid development of neutron technology and the great number of neutron sources being used. Neutrons, because of their specific physical characteristics and biological effects, form a special type of radiation hazard but, at the same time, are a prospective tool for applied radiobiology. This Symposium, held in Brookhaven at the invitation of the United States Government from 7-11 October 1963, provided an opportunity for scientists to discuss the experimental information at present available on the biological action of neutrons and to evaluate future possibilities. It was a sequel to the Symposium on Neutron Detection, Dosimetry and Standardization, which was organized by the International Atomic Energy Agency in December 1962 at Harwell. The Symposium was attended by 128 participants from 17 countries and 6 international organizations. Fifty-four papers were presented. The following subjects were discussed in various sessions: (1) Dosimetry. Estimation of absorbed dose of neutrons in biological material. (2) Biological effects of high-energy protons. (3) Cellular and genetic effects. (4) Pathology of neutron irradiation, including acute and chronic radiation syndromes (mortality, anatomical and histological changes, biochemical and metabolic disturbances) and delayed consequences. (5) Relative biological effectiveness of neutrons evaluated by different biological tests. A Panel on Biophysical Considerations in Neutron Experimentation, with special emphasis on informal discussions, was organized during the Symposium. The views of the Panel are recorded in Volume II of the Proceedings. Many reports were presented on the important subject of the relative effectiveness of the biological action of neutrons, as well as on the general pathology of neutron irradiation and the cellular and genetic effects related to it. Three survey papers considered

  6. Biological Effects of Neutron and Proton Irradiations. Vol. II. Proceedings of the Symposium on Biological Effects of Neutron Irradiations

    International Nuclear Information System (INIS)

    During recent years the interest in biological effects caused by neutrons has been increasing steadily as a result of the rapid development of neutron technology and the great number of neutron sources being used. Neutrons, because of their specific physical characteristics and biological effects, form a special type of radiation hazard but, at the same time, are a prospective tool for applied radiobiology. This Symposium, held in Brookhaven at the invitation of the United States Government from 7-11 October 1963, provided an opportunity for scientists to discuss the experimental information at present available on the biological action of neutrons and to evaluate future possibilities. It was a sequel to the Symposium on Neutron Detection, Dosimetry and Standardization, which was organized by the International Atomic Energy Agency in December 1962 at Harwell. The Symposium was attended by 128 participants from 17 countries and 6 international organizations. Fifty-four papers were presented. The following subjects were discussed in various sessions: (1) Dosimetry. Estimation of absorbed dose of neutrons in biological material. (2) Biological effects of high-energy protons. (3) Cellular and genetic effects. (4) Pathology of neutron irradiation, including acute and chronic radiation syndromes (mortality, anatomical and histological changes, biochemical and metabolic disturbances) and delayed consequences. (5) Relative biological effectiveness of neutrons evaluated by different biological tests. A Panel on Biophysical Considerations in Neutron Experimentation, with special emphasis on informal discussions, was organized during the Symposium. The views of the Panel are recorded in Volume II of the Proceedings. Many reports were presented on the important subject of the relative effectiveness of the biological action of neutrons, as well as on the general pathology of neutron irradiation and the cellular and genetic effects related to it. Three survey papers considered

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

    International Nuclear Information System (INIS)

    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 60Co and 137Cs 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 60Co: Y = (3 46 +- 2.14)10-4 cGy-1 + (3.45 +- 0

  8. Dose to tissues and effective dose equivalent by inhalation of radon-222, radon-220 and their short-lived daughters

    International Nuclear Information System (INIS)

    In this study the results of a sensitivity analysis are described which shows the influence of relevant physical and biological parameters on the dose from inhaled Rn-222, Rn-220 and their daughters to the basal cell layer of the bronchi, to the pulmonary tissues and to other body tissues. The used models for deposition, retention and dosimetry of inhaled daughters take into regard the variation of following parameters: The AMAD of inhaled radioactive particles; the fraction of unattached daughters atoms; the velocity of ciliary transport; the desorption rate of attached daughter atoms from their particles; the absorption rate to blood; and the depth of the basal cell layer in the bronchial generations. A computer programme was set-up for the calculation of the activity and dose distribution in the lungs as function of these parameters. For the evaluation of the effective dose from inhaled mixtures of Rn-222- and Rn-220-daughters three different alternatives for the weighting of the mean doses to the target tissues in the lungs are described, taking into regard possible differences between the cancerogenic sensitivity of the target cells in the bronchial and alveolar region. On the basis of the results of this sensitivity analysis mean values for the effective dose to adults per unit of inhaled potential α-energy (in Joule) and per unit of potential α-energy (in WLM) of daughters mixtures are derived as function of the unattached fraction of potential α-energy in air and the desorption half-life time of attached daughter atoms in the lungs. In addition the effective dose from inhaled Rn-222 and Rn-220 (+ Po-216) is estimated and compared with the effective dose from inhaled daughters. Finally the consequences for the assessment of intake and exposure limits for workers and for members of the public are outlined. (orig.)

  9. Biological stress response terminology: Integrating the concepts of adaptive response and preconditioning stress within a hormetic dose-response framework

    International Nuclear Information System (INIS)

    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

  10. Dose evaluation and effective dose estimation from CT fluoroscopy-guided lung biopsy

    International Nuclear Information System (INIS)

    The development of computerized tomography (CT) has made CT fluoroscopy possible with real-time CT images. However examination are expected to have high medical and occupational exposures. Then, exposures to patients and operating and assisting physicians during the CT fluoroscopy-guided lung biopsy were estimated. And changes in the examination conditions to lower the dose were made. Patient exposure was measured using an anthropomorphic phantom by simulation of clinical examination conditions. The surface dose to the physician was measured during actual clinical examinations. The average effective dose for the patient was 34±22 mSv. The highest surface dose amounted to 1.9 Gy, although this was in a very narrow field. Patient doses could be reduced by a factor of 2.5-3 by changing examination methods while still retaining diagnostic quality. The highest dose to the operating physician was 10 mGy which was recorded on the back of the hand and the average effective dose was estimated as 5.99 μSv per 1-minute examination. Doses were reduced by about a factor of 50 by lowering the tube voltage from 120 kV to 80 kV and using a supplementary tool. The doses for assisting physicians were not significant. The exposure for physicians and patients was much affected by lowering the tube voltage used for fluoroscopy. Using a supplementary tool was effective for reducing the dose for physicians. (author)

  11. Biological effects of proton radiation: an update

    International Nuclear Information System (INIS)

    Proton radiation provides significant dosimetric advantages when compared with gamma radiation due to its superior energy deposition characteristics. Although the physical aspects of proton radiobiology are well understood, biological and clinical endpoints are understudied. The current practice to assume the relative biological effectiveness of low linear energy transfer (LET) protons to be a generic value of about 1.1 relative to photons likely obscures important unrecognised differentials in biological response between these radiation qualities. A deeper understanding of the biological properties induced by proton radiation would have both radiobiological and clinical impact. This article briefly points to some of the literature pertinent to the effects of protons on tissue-level processes that modify disease progression, such as angiogenesis, cell invasion and cancer metastasis. Recent findings hint that proton radiation may, in addition to offering improved radio-therapeutic targeting, be a means to provide a new dimension for increasing therapeutic benefits for patients by manipulating these tissue-level processes. (authors)

  12. Efficacy of bio-effect dose and overall treatment time in radiotherapy of carcinoma of cervix: a prospective study

    International Nuclear Information System (INIS)

    To study the response of tumour and early rectal complications in patients of cervical cancer who underwent radiotherapy on the basis of biological effective dose (BED) and overall treatment time (OTT)

  13. Dose estimation by biological methods; Estimacion de dosis por metodos biologicos

    Energy Technology Data Exchange (ETDEWEB)

    Guerrero C, C.; David C, L.; Serment G, J.; Brena V, M. [Instituto Nacional de Investigaciones Nucleares, A.P. 18-1027, 11801 Mexico D.F. (Mexico)

    1997-07-01

    The human being is exposed to strong artificial radiation sources, mainly of two forms: the first is referred to the occupationally exposed personnel (POE) and the second, to the persons that require radiological treatment. A third form less common is by accidents. In all these conditions it is very important to estimate the absorbed dose. The classical biological dosimetry is based in the dicentric analysis. The present work is part of researches to the process to validate the In situ Fluorescent hybridation (FISH) technique which allows to analyse the aberrations on the chromosomes. (Author)

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

    International Nuclear Information System (INIS)

    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)

  15. Effect of hip prostheses on radiotherapy dose

    International Nuclear Information System (INIS)

    A small but growing proportion of patients requiring radiotherapy for prostate cancer have one or two hip prostheses which may shadow the target and affect the dose distribution. Approximately 10 such patients are treated at the Illawarra Cancer Care Centre per year. Hence a study was undertaken to examine the accuracy of various treatment methods that involve some of the treatment fields travelling through the prosthesis. A fixed-field measurement showed a dose reduction of 52% in the shadow of the prosthesis. A Monte Carlo simulation confirmed an increase in dose on the distal surface of the prosthesis of 35%. Of more clinical relevance, however, is the dose distribution due to the overall combined field treatment. Using a power law correction benchmarked against thermoluminescent dosimeters and Gafchromic film, three different beam set-ups for patient treatment were planned and the dose variation analysed. A four-field brick technique gave a dose variation across the target volume of ± 15% whereas a dual arc technique gave a dose variation of only ± 5%. A four-field oblique technique gave a dose variation of only ± 2% across the target volume but the oblique field technique included extra dose to the rectum. Copyright (2000) Blackwell Science Pty Ltd

  16. Collective effective dose equivalent, population doses and risk estimates from occupational exposures in Japan

    International Nuclear Information System (INIS)

    Collective dose equivalent and population dose from occupational exposures in Japan, 1988 were estimated on the basis of a nationwide survey. The survey was conducted on annual collective dose equivalents by sex, age group and type of radiation work for about 0.21 million workers except for the workers in nuclear power stations. The data on the workers in nuclear power stations were obtained from the official report of the Japan Nuclear Safety Commission. The total number of workers including nuclear power stations was estimated to be about 0.26 million. Radiation works were subdivided as follows: medical works including dental; non-atomic energy industry; research and education; atomic energy industry and nuclear power station. For the determination of effective dose equivalent and population dose, organ or tissue doses were measured with a phantom experiment. The resultant doses were compared with the doses previously calculated using a chord length technique and with data from ICRP publications. The annual collective effective dose equivalent were estimated to be about 21.94 person·Sv for medical workers, 7.73 person·Sv for industrial workers, 0.75 person·Sv for research and educational workers, 2.48 person·Sv for atomic energy industry and 84.4 person ·Sv for workers in nuclear power station. The population doses were calculated to be about 1.07 Sv for genetically significant dose, 0.89 Sv for leukemia significant dose and 0.42 Sv for malignant significant dose. The population risks were estimated using these population doses. (author)

  17. Topics on study of low dose-effect relationship

    International Nuclear Information System (INIS)

    It is not exceptional but usually observed that a dose-effect relationship in biosystem is not linear. Sometimes, the low dose-effect relationship appears entirely contrary to the expectation from high dose-effect. This is called a 'hormesis' phenomena. A high dose irradiation inflicts certainly an injury on biosystem. No matter how low the dose may be, an irradiation might inflict some injury on biosystem according to Linear Non-Threshold hypothesis(LNT). On the contrary to the expectation, a low dose irradiation stimulates immune system, and promotes cell proliferation. This is called 'radiation hormesis'. The studies of the radiation hormesis are made on from four points of view as follows: (1) radiation adaptive response, (2) revitalization caused by a low dose stimulation, (3) a low dose response unexpected from the LNT hypothesis, (4) negation of the LNT hypothesis. The various empirical proofs of radiation hormesis are introduced in the report. (M . Suetake)

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

    CERN Document Server

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

    2015-01-01

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

  19. Biological Stress Response Terminology: Integrating the Concepts of Adaptive Response and Preconditioning Stress Within a Hormetic Dose-Response Framework

    Science.gov (United States)

    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 stres...

  20. Red bone marrow doses, integral absorbed doses, and somatically effective dose equivalent from four maxillary occlusal projections

    International Nuclear Information System (INIS)

    Phantom measurements of red bone marrow (RBM) doses, integral absorbed doses, and somatically effective dose equivalent (SEDE) from four different maxillary occlusal projections are presented. For each projection, different combinations of focus-skin distances and tube potentials were compared with regard to the patient's radiation load. The axial incisal view produced the highest patient exposures, with a maximum red bone marrow dose of 122.5 microGy/exposure, integral absorbed dose of 8.6 mJ/exposure, and SEDE values of 39.6 microSv/exposure. The corresponding values from the frontal, lateral occlusal, and tuber views ranged between 4% and 44% of the axial incisal view values for the integral absorbed dose and SEDE values, and between 0.3% and 3% for the red bone marrow doses. Increasing the focus-skin distance from 17.5 cm to 27 cm is accompanied by a 24% to 30% reduction in integral absorbed dose. Increasing the tube potential from 50 kV to 65 kV likewise results in a 23% reduction in absorbed energy

  1. Red bone marrow doses, integral absorbed doses, and somatically effective dose equivalent from four maxillary occlusal projections

    Energy Technology Data Exchange (ETDEWEB)

    Berge, T.I.; Wohni, T.

    1984-02-01

    Phantom measurements of red bone marrow (RBM) doses, integral absorbed doses, and somatically effective dose equivalent (SEDE) from four different maxillary occlusal projections are presented. For each projection, different combinations of focus-skin distances and tube potentials were compared with regard to the patient's radiation load. The axial incisal view produced the highest patient exposures, with a maximum red bone marrow dose of 122.5 microGy/exposure, integral absorbed dose of 8.6 mJ/exposure, and SEDE values of 39.6 microSv/exposure. The corresponding values from the frontal, lateral occlusal, and tuber views ranged between 4% and 44% of the axial incisal view values for the integral absorbed dose and SEDE values, and between 0.3% and 3% for the red bone marrow doses. Increasing the focus-skin distance from 17.5 cm to 27 cm is accompanied by a 24% to 30% reduction in integral absorbed dose. Increasing the tube potential from 50 kV to 65 kV likewise results in a 23% reduction in absorbed energy.

  2. Biological Effects of Irradiated Fats

    International Nuclear Information System (INIS)

    Rats were fed with a diet containing 20% of irradiated oils. If the oils were irradiated with 2.5 Mrad, there was no indication of detrimental effects during the course of 80 weeks. Oils irradiated with 10 Mrad, however, caused an increase in lethality after a lag period of 9 to 12 months. Irradiation with 50 Mrad caused weight losses after 24 weeks, disturbed liver function, and hypoproteinaemia, with a relative increase in gamma globulins. No animal of this group exceeded a life-span of 75 weeks. Irradiation with 100 Mrad caused immediate toxic symptoms and a high lethality. There is no indication that peroxides are responsible for the toxicity of the irradiated oils. Because of the high content of dimeric products in the irradiated oils, it is assumed that dimerization of fatty acids is the cause of damage. (author)

  3. Development of Two-Dosemeter Algorithm for Better Estimation of Effective Dose Equivalent and Effective Dose

    International Nuclear Information System (INIS)

    An optimal algorithm, which suitably combines two dosemeter readings, one dosemeter on the chest and the other on the back, for better estimation of effective dose equivalent (HE) and effective dose (E), was developed by utilising hundreds of broad parallel photon beam irradiation geometries. The developed algorithm, weighting front (chest) and back dosemeter readings by 0.58 and 0.42, respectively, was found to be superior to other currently available algorithms, neither underestimating HE or E by more than 14%, nor overestimating by more than a few tens of a per cent for a broad range of frontal and dorsal incident beams. Like other algorithms, however, this algorithm tends to overestimate HE and E significantly for the lateral, overhead and underfoot beam directions. This study also suggests that this overestimation problem significantly decreases when one uses typical commercial dosemeters instead of isotropic-responding dosemeters. (author)

  4. Estimation of organ doses and effective doses in image-guided respiration-gated radiotherapy

    International Nuclear Information System (INIS)

    Dose conformity in thoracic and abdominal ion-beam radiotherapy is degraded by respiratory motion. To improve conformity, an image-guided respiration-gated system can be used in the treatment room. The purpose of this study was to estimate the organ doses and effective doses to patients from an image-guided respiration-gated system. Glass dosemeters were inserted into an adult anthropomorphic phantom and were attached to the surface on the phantom. The phantom was placed on the treatment couch, and the imaging dose from fluoroscopy was evaluated. In addition to the organ doses, the effective doses were also estimated according to the ICRP Publication 103. The irradiation time is over 3-5 min per beam angle. When image acquisition conditions were assumed for thoracic treatment, the effective doses and maximal skin doses were 0.48-0.79 mSv and 5.9-9.9 mGy, respectively. The estimated doses can be the base data for considering radiological protection in the radiotherapy. (authors)

  5. Estimation of absorbed organ doses and effective dose based on body mass index in digital radiography

    International Nuclear Information System (INIS)

    With the introduction of digital radiography, patients undergoing radiographic procedures are subject to being overexposed to radiation. Therefore, it is necessary to estimate the absorbed organ dose and the effective dose, which are significant for patient health, along with body type. During chest radiographic examinations conducted in 899 patients for screening, the absorbed dose of the 13 major organs, the average whole-body dose, and two effective doses weighted by factors published in ICRP 60 and ICRP 103 were calculated on the basis of patient information such as height, weight and examination condition, including kilovolt potential, focus-skin distance and entrance surface dose (ESD), using a PC-based Monte Carlo program simulation. It was found that dose per unit ESD had a tendency to decrease with body mass index (BMI). In particular, the absorbed dose for most organs was larger at high voltages (140 kVp) than at low voltages (120 kVp, 100 kVp). In addition, the effective dose which was based on ICRP 60 and ICRP 103 also represented the same tendency in respect of BMI and tube voltage. (authors)

  6. Effective dose and organ doses due to gas Bremsstrahlung from electron storage rings

    International Nuclear Information System (INIS)

    Bremsstrahlung on residual gas is an important source of beam losses in electron-positron storage rings. The Bremsstrahlung photons are emitted in a narrow cone in the forward direction, which produces a 'hot spot' of dose at the end of a straight section. Estimates of radiation hazard due to gas Bremsstrahlung have so far been performed by calculating the maximum dose equivalent (MADE) or similar quantities. However, the use of quantities conceived for broad parallel beams in the case of very narrow beams significantly overestimates the organ doses and effective dose. In this paper a more sophisticated computational model was used to calculate values of effective dose and absorbed doses in various organs due to gas Bremsstrahlung X-rays generated by 0.1-10 GeV electrons. The Bremsstrahlung photons generated by the interaction of a mono-energetic electron beam in a 1 m long air target were made to impinge on a selected organ of an hermaphrodite anthropomorphic mathematical model placed at 1 and 10 m distances from the end of the target. Organ dose and effective dose were calculated for five representative organs, namely the right eye, ovaries, breast, testes and thyroid. Fits to the calculated values are given, as well as the dependence of photon fluence and dosimetric quantities on various parameters. The results are compared with previous estimates based on MADE and with values of ambient dose equivalent. (authors)

  7. Biological dose estimation of partial body exposures in cervix cancer patients

    International Nuclear Information System (INIS)

    At present, unstable chromosome aberrations analysis in peripheral blood lymphocytes is the most sensitive method to provide a biological estimation of the dose in accidental radiation over exposures. The assessment of the dose is particularly reliable in cases of acute, uniform, whole-body exposures or after irradiation of large parts of the body. However, the scenarios of most radiation accidents result in partial-body exposures or non-uniform dose distribution, leading to a differential exposure of lymphocytes in the body. Inhomogeneity produces a yield of dicentrics, which does not conform to a Poisson distribution, but is generally over dispersed. This arises because those lymphocytes in tissues outside the radiation field will not be damaged. Most of the lymphocytes (80 %) belong to the 'redistributional pool' (lymphatic tissues and other organs) and made recirculate into peripheral blood producing a mixed irradiated and unirradiated population of lymphocytes. So-called over dispersion, with a variance greater than the mean, can be taken as an indication of non-uniform exposure. The main factors operating in vivo partial-body irradiation may be the location and size of the irradiation field and, at high doses, various cellular reactions such as reduced blast transformation, mitotic delay or interphase death may contribute. For partial-body exposures, mathematical-statistical analysis of chromosome aberration data can be performed to derive a dose estimate for the irradiated fraction of the body, been more realistic than to quote a mean equivalent uniform whole body dose. The 'Contaminated Poisson' method of Dolphin or the Qdr method of Sasaki, both based on similar principles, can achieve this. Contaminated Poisson considers the over dispersed distribution of dicentrics among all the cells scored. The observed distribution is considered to be the sum of a Poisson distribution, which represents the irradiated fraction of the body, and the remaining unexposed

  8. Biological Effects Of Artificial Illumination

    Science.gov (United States)

    Corth, Richard

    1980-10-01

    We are increasingly being warned of the possible effects of so called "polluted" light, that is light that differs in spectral content from that of sunlight. We should be concerned, we are told, because all animals and plants have evolved under this natural daylight and therefore any difference between that illuminant and the artificial illuminants that are on the market today, is suspect. The usual presentation of the differences between the sunlight and the artificial illuminants are as shown in Figure 1. Here we are shown the spectral power distribution of sunlight and Cool White fluorescent light. The spectral power distributions of each have been normalized to some convenient wavelength so that each can be seen and easily compared on the same figure. But this presentation is misleading for one does not experience artificial illuminants at the same intensity as one experiences sunlight. Sunlight intensities are ordinarily found to be in the 8000 to 10,000 footcandle range whereas artificial illuminants are rarely experienced at intensity levels greater than 100 footcandles. Therefore a representative difference between the two types of illumination conditions is more accurately represented as in Figure 2. Thus if evolutionary adaptations require that humans and other animals be exposed to sunlight to ensure wellbeing, it is clear that one must be exposed to sunlight intensities. It is not feasible to expect that artificially illuminated environments will be lit to the same intensity as sunlight

  9. Prostate cancer: biological dose considerations and constraints in tele- and brachytherapy

    International Nuclear Information System (INIS)

    In Europe, prostate cancer is the most frequently diagnosed malignancy in men. Radiotherapy is an effective treatment option, which, however, is inevitably associated with exposure of rectum and urinary bladder to significant doses. Hence, radiobiological parameters of both prostate tumors and normal tissues to be considered in prescribing treatment, such as the effect of overall treatment time, dose fractionation and exposed volume, will be discussed in this review. For the treatment of localized prostate tumors (T1-2N0M0, G1-2, Gleason 6, PSA>20; T3) are treated with conformal EBRT (5 x 1.8-2.0 Gy/week) to 74-78 Gy, or with a combination of EBRT (30-50 Gy) and HDRBT (12-30 Gy/2-4 F) to total doses of 58-80 Gy. (orig.)

  10. Biological effects of low level exposures to chemicals and radiation

    International Nuclear Information System (INIS)

    In May 1990 a group of scientists representing several federal agencies, the International Society of Regulatory Toxicology and Pharmacology, the private sector, and academia met to develop a strategy to encourage the study of the biological effects of low level exposures (BELLE) to chemical agents and radioactivity. A workshop was held in 1991 with seven invited speakers focusing on the toxicological implications of biological adaptations. The selection of topics and speakers was designed to consider critically the concept of hormesis, not only in a broad, conceptual manner, but also at the molecular and biochemical levels. These presentations offered a complementary perspective on the diverse range of molecular mechanisms that can become activated at low levels of toxicant exposure. In addition to chemical toxicology research, an overview of current research on 'Effects of low-dose radiation on the immune response' was presented as well as 'Cellular adaptation as an important response during chemical carcinogenesis'. The final presentation was devoted to biostatistical considerations when designing studies that address issues associated with the biological responses to low doses of chemicals and radiation, as well as issues in interpretation of the findings from such studies

  11. Biological Effect of Magnetic Field in Mice

    Institute of Scientific and Technical Information of China (English)

    Zhao-Wei ZENG

    2005-01-01

    Objective: To study the biological effect of magnetic field in mice bodies. Method: With a piece of permanent magnet embeded in mice bodies beside the femoral artery and vein to measure the electrophoretic velocity(um/s). Result: The magnetic field in mice bodies on the experiment group that the electrophoretic velocity is faster more than control and free group.Conclusion:The magnetic field in animal's body can raise the negative electric charges on the surface of erythrocyte to improve the microcirculation, this is the biological effect of magnetic field.

  12. Dose Effects of Ion Beam Exposure on Deinococcus Radiodurans: Survival and Dose Response

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    To explore the survival and dose response of organism for different radiation sources is of great importance in the research of radiobiology. In this study, the survival-dose response of Deinococcus radiodurans (E.coli, as the control) for ultra-violet (UV), γ-rays radiation and ion beam exposure was investigated. The shoulder type of survival curves were found for both UV and γ-ray ionizing radiation, but the saddle type of survival curves were shown for H+ 、 N+( 20keV and 30keV) and Ar+ beam exposure. This dose effect of the survival initially decreased withthe increase in dose and then increased in the high dose range and finally decreased again in thehigher dose range. Our experimental results suggest that D. radiodurans, which is considerablyradio-resistant to UV and x-ray and γ-ray ionizing radiation, do not resist ion beam exposure.

  13. Preliminary study on biological effects of pea seeds (Pisum sativum L.) induced by 252Cf neutron source

    International Nuclear Information System (INIS)

    Background: The doses and biological effects of irradiated plants have been studied and reported widely. In the research, Co-60 gamma-ray source was more often used than the neutron source. However, fast neutron source is promising in such irradiation studies as it has many advantages, such as strong biological effect, high mutation rate, wide variation spectrum and stable mutant. Purpose: We aim to explore the method of dose calculation in pea samples. The biological effects of pea seeds (Pisum sativum L.) induced by different radioactive doses are to be investigated. Methods: The Needle Leaf Pea seeds were irradiated using 252Cf fission neutron source. The Monte Carlo simulation MCNP4C code was used to calculate the neutron absorbed doses and γ-rays (photons) absorbed doses in the samples. The biological effects of pea seeds induced by different radioactive doses were investigated. Results: The results showed that the flowering time of Ml generation peas was delayed with lower neutron absorbed doses (0.239-4.330 Gy), and the germination rate was promoted with micro-absorbed doses. The seedling branch rate of Ml generation peas was elevated by neutron radiation. The harvest of Ml generation was increased with appropriate neutron doses (0.619 Gy) irradiating peas. Conclusion: After being irradiated by low neutron doses (0.239-4.330 Gy), M1 generation peas show obvious biological effects. The research results have positive significance for the agricultural production and breeding. (authors)

  14. Dose dependence on stochastic radiobiological effect in radiation risk estimation

    International Nuclear Information System (INIS)

    The analysis of the results in dose -- effect relationship observation has been carried out on the cell and organism levels, with the aim to obtain more precise data on the risk coefficients at low doses. The results are represented by two contrasting groups of dose dependence on effect: a downwards concave and a J-shaped curve. Both types of dependence are described by the equation solutions of an assumed unified protective mechanism, which comprises two components: constitutive and adaptive or inducible ones. The latest data analysis of the downwards concave dependence curves shows a considerable underestimation of radiation risk in all types of cancer, except leukemia, for a number of critical groups in a population, at low doses comparing to the ICRP recommendations. With the dose increase, the decrease of the effect value per dose unit is observed. It may be possibly related to the switching of the activity of the adaptive protective mechanism, with some threshold dose values being exceeded

  15. Mechanisms and biological importance of photon-induced bystander responses. Do they have an impact on low-dose radiation responses

    International Nuclear Information System (INIS)

    Elucidating the biological effect of low linear energy transfer (LET), low-dose and/or low-dose-rate ionizing radiation is essential in ensuring radiation safety. Over the past two decades, non-targeted effects, which are not only a direct consequence of radiation-induced initial lesions produced in cellular DNA but also of intra- and inter-cellular communications involving both targeted and non-targeted cells, have been reported and are currently defining a new paradigm in radiation biology. These effects include radiation-induced adaptive response, low-dose hypersensitivity, genomic instability, and radiation-induced bystander response (RIBR). RIBR is generally defined as a cellular response that is induced in non-irradiated cells that receive bystander signals from directly irradiated cells. RIBR could thus play an important biological role in low-dose irradiation conditions. However, this suggestion was mainly based on findings obtained using high-LET charged-particle radiations. The human population (especially the Japanese, who are exposed to lower doses of radon than the world average) is more frequently exposed to low-LET photons (X-rays or γ-rays) than to high-LET charged-particle radiation on a daily basis. There are currently a growing number of reports describing a distinguishing feature between photon-induced bystander response and high-LET RIBR. In particular, photon-induced by-stander response is strongly influenced by irradiation dose, the irradiated region of the targeted cells, and p53 status. The present review focuses on the photon-induced bystander response, and discusses its impact on the low-dose radiation effect. (author)

  16. Dose reconstruction in deforming lung anatomy: Dose grid size effects and clinical implications

    International Nuclear Information System (INIS)

    In this study we investigated the accumulation of dose to a deforming anatomy (such as lung) based on voxel tracking and by using time weighting factors derived from a breathing probability distribution function (p.d.f.). A mutual information registration scheme (using thin-plate spline warping) provided a transformation that allows the tracking of points between exhale and inhale treatment planning datasets (and/or intermediate state scans). The dose distributions were computed at the same resolution on each dataset using the Dose Planning Method (DPM) Monte Carlo code. Two accumulation/interpolation approaches were assessed. The first maps exhale dose grid points onto the inhale scan, estimates the doses at the 'tracked' locations by trilinear interpolation and scores the accumulated doses (via the p.d.f.) on the original exhale data set. In the second approach, the 'volume' associated with each exhale dose grid point (exhale dose voxel) is first subdivided into octants, the center of each octant is mapped to locations on the inhale dose grid and doses are estimated by trilinear interpolation. The octant doses are then averaged to form the inhale voxel dose and scored at the original exhale dose grid point location. Differences between the interpolation schemes are voxel size and tissue density dependent, but in general appear primarily only in regions with steep dose gradients (e.g., penumbra). Their magnitude (small regions of few percent differences) is less than the alterations in dose due to positional and shape changes from breathing in the first place. Thus, for sufficiently small dose grid point spacing, and relative to organ motion and deformation, differences due solely to the interpolation are unlikely to result in clinically significant differences to volume-based evaluation metrics such as mean lung dose (MLD) and tumor equivalent uniform dose (gEUD). The overall effects of deformation vary among patients. They depend on the tumor location, field

  17. Dose rate effect in food irradiation

    International Nuclear Information System (INIS)

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

  18. From Chernobyl to Fukushima: the effect of low doses

    International Nuclear Information System (INIS)

    This Power Point presentation describes the Fukushima's reactors, recalls some data about the earthquake and tsunami, and indicates their consequences for the operation of the power station (notably the loss of cooling means). It identifies some design errors for the Chernobyl's and Fukushima's power stations, outlines differences between these two cases. It gives assessment of doses receives by external irradiation around Fukushima, of the dose rate evolution, of the sea contamination. It gives some data about the Chernobyl accident (radioactivity evolution). After some data about health consequences of Chernobyl, health risks and more particularly biological risks associated to low doses are described. Protection measures are evoked, as well as psycho-social impacts

  19. Biological effectiveness of neutrons: Research needs

    Energy Technology Data Exchange (ETDEWEB)

    Casarett, G.W.; Braby, L.A.; Broerse, J.J.; Elkind, M.M.; Goodhead, D.T.; Oleinick, N.L.

    1994-02-01

    The goal of this report was to provide a conceptual plan for a research program that would provide a basis for determining more precisely the biological effectiveness of neutron radiation with emphasis on endpoints relevant to the protection of human health. This report presents the findings of the experts for seven particular categories of scientific information on neutron biological effectiveness. Chapter 2 examines the radiobiological mechanisms underlying the assumptions used to estimate human risk from neutrons and other radiations. Chapter 3 discusses the qualitative and quantitative models used to organize and evaluate experimental observations and to provide extrapolations where direct observations cannot be made. Chapter 4 discusses the physical principles governing the interaction of radiation with biological systems and the importance of accurate dosimetry in evaluating radiation risk and reducing the uncertainty in the biological data. Chapter 5 deals with the chemical and molecular changes underlying cellular responses and the LET dependence of these changes. Chapter 6, in turn, discusses those cellular and genetic changes which lead to mutation or neoplastic transformation. Chapters 7 and 8 examine deterministic and stochastic effects, respectively, and the data required for the prediction of such effects at different organizational levels and for the extrapolation from experimental results in animals to risks for man. Gaps and uncertainties in this data are examined relative to data required for establishing radiation protection standards for neutrons and procedures for the effective and safe use of neutron and other high-LET radiation therapy.

  20. Biological effectiveness of neutrons: Research needs

    International Nuclear Information System (INIS)

    The goal of this report was to provide a conceptual plan for a research program that would provide a basis for determining more precisely the biological effectiveness of neutron radiation with emphasis on endpoints relevant to the protection of human health. This report presents the findings of the experts for seven particular categories of scientific information on neutron biological effectiveness. Chapter 2 examines the radiobiological mechanisms underlying the assumptions used to estimate human risk from neutrons and other radiations. Chapter 3 discusses the qualitative and quantitative models used to organize and evaluate experimental observations and to provide extrapolations where direct observations cannot be made. Chapter 4 discusses the physical principles governing the interaction of radiation with biological systems and the importance of accurate dosimetry in evaluating radiation risk and reducing the uncertainty in the biological data. Chapter 5 deals with the chemical and molecular changes underlying cellular responses and the LET dependence of these changes. Chapter 6, in turn, discusses those cellular and genetic changes which lead to mutation or neoplastic transformation. Chapters 7 and 8 examine deterministic and stochastic effects, respectively, and the data required for the prediction of such effects at different organizational levels and for the extrapolation from experimental results in animals to risks for man. Gaps and uncertainties in this data are examined relative to data required for establishing radiation protection standards for neutrons and procedures for the effective and safe use of neutron and other high-LET radiation therapy

  1. Evaluation of radiobiological effects in 3 distinct biological models

    International Nuclear Information System (INIS)

    on the field) for the study of biological effects of low doses of ionizing radiation, believing that there is a clear lack of data related with the biological effects of low doses of ionizing radiation. It is our goal to study the radiobiological effects of those levels of radiation - the medical imaging levels, that characterizes the Nuclear Medicine and Radiology typical environments. (authors)

  2. Radiobiological impact of dose calculation algorithms on biologically optimized IMRT lung stereotactic body radiation therapy plans

    International Nuclear Information System (INIS)

    The aim of this study is to evaluate the radiobiological impact of Acuros XB (AXB) vs. Anisotropic Analytic Algorithm (AAA) dose calculation algorithms in combined dose-volume and biological optimized IMRT plans of SBRT treatments for non-small-cell lung cancer (NSCLC) patients. Twenty eight patients with NSCLC previously treated SBRT were re-planned using Varian Eclipse (V11) with combined dose-volume and biological optimization IMRT sliding window technique. The total dose prescribed to the PTV was 60 Gy with 12 Gy per fraction. The plans were initially optimized using AAA algorithm, and then were recomputed using AXB using the same MUs and MLC files to compare with the dose distribution of the original plans and assess the radiobiological as well as dosimetric impact of the two different dose algorithms. The Poisson Linear-Quadatric (PLQ) and Lyman-Kutcher-Burman (LKB) models were used for estimating the tumor control probability (TCP) and normal tissue complication probability (NTCP), respectively. The influence of the model parameter uncertainties on the TCP differences and the NTCP differences between AAA and AXB plans were studied by applying different sets of published model parameters. Patients were grouped into peripheral and centrally-located tumors to evaluate the impact of tumor location. PTV dose was lower in the re-calculated AXB plans, as compared to AAA plans. The median differences of PTV(D95%) were 1.7 Gy (range: 0.3, 6.5 Gy) and 1.0 Gy (range: 0.6, 4.4 Gy) for peripheral tumors and centrally-located tumors, respectively. The median differences of PTV(mean) were 0.4 Gy (range: 0.0, 1.9 Gy) and 0.9 Gy (range: 0.0, 4.3 Gy) for peripheral tumors and centrally-located tumors, respectively. TCP was also found lower in AXB-recalculated plans compared with the AAA plans. The median (range) of the TCP differences for 30 month local control were 1.6 % (0.3 %, 5.8 %) for peripheral tumors and 1.3 % (0.5 %, 3.4 %) for centrally located tumors. The lower TCP

  3. Absorbed dose measurements using TLDS in biological samples from beta radiation

    Directory of Open Access Journals (Sweden)

    José Eduardo Manzoli

    2006-01-01

    Full Text Available Irradiation of samples in peculiar experimental apparatus, subject to radiation spread, requires a special evaluation of absorbed dose implanted to the sample. Indirect calibration of the irradiation source, obtained in a different apparatus, and the spread, usually of very difficult theoretical evaluation, can cause very serious measurement errors, sometimes reaching 50%. In this work, the procedure for dose evaluation in an apparatus for beta irradiation of samples, usually biological ones,is presented, making use of calibration curves, obtained by irradiation in advance of thermoluminescent detectors in air, and so irradiating them in the same position of the sample. An application in blood sample irradiation is also presented.A irradiação de amostras em arranjos experimentais peculiares sujeitos a espalhamento necessita de uma determinação própria da dose absorvida que a amostra irá receber. A calibração indireta da fonte de irradiação, que ocorre em arranjo diferente, e o espalhamento, geralmente de difícil estimativa teórica, podem causar erros de medição muito elevados, não raro atingindo 50%. Neste trabalho é apresentado o procedimento para determinação da dose absorvida em um arranjo para irradiação beta de amostras, normalmente biológicas, utilizando curvas de calibração obtidas pela irradiação de dosímetros termoluminescentes no ar, e os irradiando na mesma posição das amostras. É apresentado um exemplo de aplicação para amostra irradiada de sangue.

  4. The relevance of radiation induced bystander effects for low dose radiation carcinogenic risk

    International Nuclear Information System (INIS)

    Full text: Where epidemiology studies lack the ability to prescribe radiation doses, customise sample sizes and replicate findings, radiobiology experiments provide greater flexibility to control experimental conditions. This control simplifies the process of answering questions concerning carcinogenic risk after low dose radiation exposures. However, the flexibility requires critical evaluation of radiobiology findings to ensure that the right questions are being asked, the experimental conditions are relevant to human exposure scenarios and that the data are cautiously interpreted in the context of the experimental model. In particular, low dose radiobiology phenomena such as adaptive responses, genomic instability and bystander effects need to be investigated thoroughly, with continual reference to the way these phenomena might occur in the real world. Low dose radiation induced bystander effects are of interest since their occurrence in vivo could complicate the shape of the radiation dose-response curve in the low dose range for a number of biological endpoints with subsequent effects on radiation-induced cancer risk. Conversely, radiation-induced abscopal effects implicate biological consequences of radiation exposure outside irradiated volumes, and complicate the notion of effective dose calculations. Achieving a consensus on the boundaries that distinguish the radiobiology phenomena of bystander and abscopal effects will aid progress towards understanding their relevance to in vivo radiation exposures. A proposed framework for discussing bystander effects and abscopal effects in their appropriate context will be outlined, with a discussion on the future investigation of radiation-induced bystander effects. Such frameworks can assist the integration of results from experimental radiobiology to risk evaluation and management practice. This research was funded by the Low Dose Radiation Research Program, BioI. and Environ. Research, US Dept. of Energy, Grant DE

  5. Low radiation dose effects - is it a myth or reality?

    International Nuclear Information System (INIS)

    The effects of low-level radiation are very difficult to observe and highly controversial. The radiation doses that result from chronic exposures but does not manifest in deterministic effects could be categorised as low radiation doses. These doses result in only potential stochastic effects which are probabilistic in nature. On the other hand, high radiation doses result in both deterministic effects and stochastic effects. Stochastic effects from higher doses are extrapolated linearly to the low doses on the basis of a hypothesis that the dose response curve is linear at all doses. This is what is termed as 'Linear No Threshold (LNT)' hypothesis. Based on this hypothesis, all regulatory agencies stipulate regulatory limits for radiation workers and for members of public. Particularly, the optimisation principle of radiation protection 'as low as reasonably achievable (ALARA)' is insisted on by regulatory bodies resulting in the often asked question as to whether it is really evidence based hypothesis or fear based regulatory concern. Many studies of high background areas in India, Iran, Brazil, etc. have not resulted in proof of excess cancer risk at radiation doses encountered in these areas of high background. Studies on large population of radiation workers who have received higher radiation doses than stipulated in the earlier periods of radiation safety limits have also not shown any increase in cancer incidence ascribable to radiation dose. On the contrary studies have shown, documented by many reputed scientific journals, American Nuclear Society, World Nuclear Agency and BEIR Committee that at low radiation doses the dose response curve is not only nonlinear but also shows a threshold for any harmful effect. (author)

  6. RELATIVE BIOLOGICAL EFFECTIVENESS IN A PROTON SOBP

    Czech Academy of Sciences Publication Activity Database

    Vachelová, Jana; Michaelidesová, Anna; Litvinchuk, Alexandra; Vondráček, V.; Davídková, Marie

    Vol. 34. Bratislava : SMU - Faculty of Public Health, 2014. s. 121-121. ISBN 978-80-89384-08-2. [XXXVI.Dny radiační ochrany. 10.11.2014-14.11.2014, Poprad] Institutional support: RVO:61389005 Keywords : relative biological effectiveness * Spread-Out Bragg Peak * linear energy transfer Subject RIV: BO - Biophysics

  7. Exploiting Allee effects for managing biological invasions

    Czech Academy of Sciences Publication Activity Database

    Tobin, P. C.; Berec, Luděk; Liebhold, A. M.

    2011-01-01

    Roč. 14, č. 6 (2011), s. 615-624. ISSN 1461-023X Grant ostatní: National Centre for Ecological Analysis and Synthesis(US) EF-0553768 Institutional research plan: CEZ:AV0Z50070508 Keywords : Allee dynamics * biological invasions * component Allee effect Subject RIV: EH - Ecology, Behaviour Impact factor: 17.557, year: 2011

  8. Effect of dose on the glucuronidation and sulphation kinetics of diflunisal in man: single dose studies.

    Science.gov (United States)

    Loewen, G R; Herman, R J; Ross, S G; Verbeeck, R K

    1988-01-01

    1. The effect of dose (100 mg, 250 mg, 500 mg, 750 mg and 1000 mg) on the glucuronidation and sulphation of diflunisal was studied in six healthy volunteers. 2. Total urinary recovery ranged from 78.9 +/- 11.9% to 91.5 +/- 18.7% of the administered dose. Urinary recovery (normalized for total urinary recovery) of diflunisal sulphate (DS) significantly increased with dose from 9.3 +/- 3.7% to 18.1 +/- 4.8%. 3. Normalized urinary recovery for diflunisal phenolic glucuronide (DPG) was unaffected by dose (range: 30.6 +/- 3.8% to 40.6 +/- 6.6%). Normalized urinary recovery for the acyl glucuronide (DAG) significantly decreased from 52.3 +/- 4.6% to 40.2 +/- 3.4% as the dose increased. 4. Total plasma clearance of diflunisal significantly decreased from 14.4 +/- 1.4 ml min-1 to 8.7 +/- 1.4 ml min-1 as the dose increased from 100 mg to 750 mg. A further increase in dose to 1000 mg resulted in an unexplained increase in total plasma clearance to 10.3 +/- 1.8 ml min-1. 5. Dose-dependent plasma clearance of diflunisal was caused mainly by saturation of the formation of DAG, whereas the formation of DS and DPG were relatively unaffected by dose. PMID:3203058

  9. Off-label biologic regimens in psoriasis: a systematic review of efficacy and safety of dose escalation, reduction, and interrupted biologic therapy.

    Directory of Open Access Journals (Sweden)

    Elizabeth A Brezinski

    Full Text Available OBJECTIVES: While off-label dosing of biologic treatments may be necessary in selected psoriasis patients, no systematic review exists to date that synthesizes the efficacy and safety of these off-label dosing regimens. The aim of this systematic review is to evaluate efficacy and safety of off-label dosing regimens (dose escalation, dose reduction, and interrupted treatment with etanercept, adalimumab, infliximab, ustekinumab, and alefacept for psoriasis treatment. DATA SOURCES AND STUDY SELECTION: We searched OVID Medline from January 1, 1990 through August 1, 2011 for prospective clinical trials that studied biologic therapy for psoriasis treatment in adults. Individual articles were screened for studies that examined escalated, reduced, or interrupted therapy with etanercept, adalimumab, infliximab, ustekinumab, or alefacept. DATA SYNTHESIS: A total of 23 articles with 12,617 patients matched the inclusion and exclusion criteria for the systematic review. Data were examined for primary and secondary efficacy outcomes and adverse events including infections, malignancies, cardiovascular events, and anti-drug antibodies. The preponderance of data suggests that continuous treatment with anti-TNF agents and anti-IL12/23 agent was necessary for maintenance of disease control. Among non-responders, dose escalation with etanercept, adalimumab, ustekinumab, and alefacept typically resulted in greater efficacy than standard dosing. Dose reduction with etanercept and alefacept resulted in reduced efficacy. Withdrawal of the examined biologics led to an increase in disease activity; efficacy from retreatment did not result in equivalent initial response rates for most biologics. Safety data on off-label dosing regimens are limited. CONCLUSION: Dose escalation in non-responders generally resulted in increased efficacy in the examined biologics used to treat moderate-to-severe psoriasis. Continuous treatment with anti-TNF agents and anti-IL12/23 agent

  10. Evaluation of effective dose equivalent from environmental gamma rays

    International Nuclear Information System (INIS)

    Organ doses and effective dose equivalents for environmental gamma rays were calculated using human phantoms and Monte Carlo methods accounting rigorously the environmental gamma ray fields. It was suggested that body weight is the dominant factor to determine organ doses. The weight function expressing organ doses was introduced. Using this function, the variation in organ doses due to several physical factors were investigated. A detector having gamma-ray response similar to that of human bodies has been developed using a NaI(Tl) scintillator. (author)

  11. The peripheral vascular effects of diltiazem--dose-response characteristics.

    OpenAIRE

    Finch, M B; Johnston, G D

    1985-01-01

    The acute effects of increasing doses of diltiazem on peripheral blood flow were observed in six subjects. Each subject received, in random order, a single oral dose of placebo or diltiazem 60, 120 or 180 mg. Supine heart rate, blood pressure, skin temperature, digital systolic pressure, forearm and digital blood flow were recorded before and at 1, 2, 3, 4 and 6 h post-dosing. Plasma diltiazem concentrations were measured at each time interval and at 12 and 24 h after the 120 mg dose. At dose...

  12. Effects of low doses: Proof and inferences; Effet des faibles doses: preuves et inferences

    Energy Technology Data Exchange (ETDEWEB)

    Hubert, Ph. [Ineris Direction des risques chroniques, 60 - Verneuil-en-Halatte (France)

    2010-07-15

    It is essential to discuss the plausibility of 'low-dose' effects from environmental exposures. The question, nonetheless, is wrongly labelled, for it is not the magnitude of the dose that matters, but rather the effect. The question thus concerns 'doses with low effects'. More precisely, because the low effects on large populations are not that small, even when epidemiological tools fail to detect them, it would be more accurate to talk about 'doses with undetectable or barely detectable effects'. Hereafter, we describe this 'low-effect dose' concept from the viewpoint of toxicology and epidemiology and discuss the fragile boundary line for these low-effect doses. Next, we review the different types of inference from observed situations (i.e., with high effects) to situations relevant to public health, to characterize the level of confidence to be accorded them. The first type is extrapolation - from higher to lower doses or from higher to lower dose rates. The second type is transposition - from humans to other humans or from animals to humans. The third type can be called 'analogy' as in 'read across' approaches, where QSAR (Quantitative Structure Activity Relationship) methodology can be used. These three types of inferences can be based on an estimate of the 'distance' between observed and predicted areas, but can also rely on knowledge and theories of the relevant mechanisms. The new tools of predictive toxicology are helpful both in deriving quantitative estimates and grounding inferences on sound bases. (author)

  13. Dose and dose rate effects on coherent-to-incoherent transition of precipitates upon irradiation

    Institute of Scientific and Technical Information of China (English)

    LI Zhengchao

    2006-01-01

    A typical precipitation hardened alloy, Cu-Co dilute alloy was selected to study the precipitation behavior and irradiation effect on precipitates. It is found that the principal effect of ion irradiation on the coherent precipitates is loss of coherency, and TEM cross-section observations show that the fraction of the incoherent precipitates is dependent on dose but not on dose rate during heavy ion irradiation.

  14. Nuclear energy: biological effects and environmental impact

    International Nuclear Information System (INIS)

    This thesis is concerned with the large development of nuclear power plants and the recent nuclear catastrophe which has made clear how the hazards resulting from radioactivity affect public health and the environment. Environmental effects of nuclear power plants operating in normal conditions are small, but to obtain nuclear power plants of reduced radioactivity, optimization of their design, construction, operation and waste processing plays a decisive role. Biological effects of ionizing radiations and environmental impacts of Nuclear Power plants are developed

  15. II. Biological studies of radiation effects

    Energy Technology Data Exchange (ETDEWEB)

    Lawrence, J.H.

    1948-05-24

    With the completion of the 184 inch cyclotron in Berkeley and the successful construction of a deflector system, it was possible to bring the 190 Mev deuteron and the 380 Mev alpha beams out into the air and to begin a study of the effects of high-energy deuteron beams by direct irradiation of biological specimens. The direct biological use of deuteron beams was attempted earlier in Berkeley by Marshak, MacLeish, and Walker in 1940. These and other investigators have been aware for some time of the potential usefulness of high energy particle beams for radio-biological studies and their suitability for biological investigations. R.R. Wilson advanced the idea of using fast proton beams to deliver radiation and intervening tissues. R.E. Zirkle pointed out that such particle beams may be focused or screened until a cross-section of the beam is small enough to study effects of irradiation under the microscope on single cells or on parts of single cells. This article gives an overview of the radiological use of high energy deuteron beams, including the following topics: potential uses of high energy particle beams; experiments on the physical properties of the beam; lethal effect of the deuteron beam on mice.

  16. Spatial interpolation of biologically effective UV radiation over Poland

    Science.gov (United States)

    Walawender, J.; Ustrnul, Z.

    2010-09-01

    The ultraviolet(UV) radiation plays an important role in the Earth-Atmosphere System. It has a positive influence on both human health and natural environment but it may also be very harmful if UV exposure exceeds "safe" limits. For that reason knowledge about spatial distribution of biologically effective UV doses seems to be crucial in minimization or complete elimination of the negative UV effects. The main purpose of this study is to find the most appropriate interpolation method in order to create reliable maps of the biologically effective UV radiation over Poland. As the broadband UV measurement network in Poland is very sparse, erythemaly weighted UV radiation data reconstructed from homogeneous global solar radiation records were used. UV reconstruction model was developed in Centre of Aerology (Institute of Meteorology and Water Management) within COST Action 726 - ‘Long term changes and climatology of UV radiation over Europe'. The model made it possible to reconstruct daily erythemal UV doses for 21 solar radiation measurement stations in the period 1985 - 2008. Mapping methodology included the following processing steps: exploratory spatial data analysis, verification of additional variables, selection and parameterization of interpolation model, accuracy assessment and cartographic visualization. Several different stochastic and deterministic interpolation methods along with various empirical semivariogram models were tested. Multiple regression analysis was performed in order to examine statistical relationship between UV radiation and additional environmental variables such as: elevation, latitude, stratospheric ozone content and cloud cover. The data were integrated, processed and visualized within GIS environment.

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

    International Nuclear Information System (INIS)

    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

  18. Lunar biological effects and the magnetosphere.

    Science.gov (United States)

    Bevington, Michael

    2015-12-01

    The debate about how far the Moon causes biological effects has continued for two millennia. Pliny the Elder argued for lunar power "penetrating all things", including plants, fish, animals and humans. He also linked the Moon with tides, confirmed mathematically by Newton. A review of modern studies of biological effects, especially from plants and animals, confirms the pervasive nature of this lunar force. However calculations from physics and other arguments refute the supposed mechanisms of gravity and light. Recent space exploration allows a new approach with evidence of electromagnetic fields associated with the Earth's magnetotail at full moon during the night, and similar, but more limited, effects from the Moon's wake on the magnetosphere at new moon during the day. The disturbance of the magnetotail is perhaps shown by measurements of electric fields of up to 16V/m compared with the usual electromagnetic radiation are known to affect animals and 10-20% of the human population. There is now evidence for mechanisms such as calcium flux, melatonin disruption, magnetite and cryptochromes. Both environmental and receptor variations explain confounding factors and inconsistencies in the evidence. Electromagnetic effects might also account for some evolutionary changes. Further research on lunar biological effects, such as acute myocardial infarction, could help the development of strategies to reduce adverse effects for people sensitive to geomagnetic disturbance. PMID:26462435

  19. The time factor in dose-effect relationships

    International Nuclear Information System (INIS)

    The assumption that carcinogenic risk is proportional to dose fails to consider that probable time of actual cancer incidence. The time lag between exposure and carcinogenic effect for radiation and chemical agents varies as Dosesup(-1/n), with napproximately3. A model is offered explaining that concentration of initially altered cells depends on dose, whereas their chance for development into tumours on their proximity, which varies as Dsup(-1/3). Because of biological variability, n has a range of values. The model implies that tumours resulting from a single exposure should be closely distributed in time, producing a pulse of cases and subsequently being essentially without effect. Testing of the Dsup(-1/3) rule was extended and its model, by further refinement of methods, applied to radiogenic leukaemia risk and to the effect of urethan in inducing lung tumours in mice with and without radiation exposure as a possible cocarcinogen. Radiation did not affect the tumour yield from urethan in mice. Radiogenic leukaemia and lung tumours induced by urethan both occur in proportion to exposure, but the time of their occurrence is limited to a short interval in relation to life span. Similarly, in murine or in human radiogenic leukaemia, leukaemia risk occurs in proportion to exposure, but the time of occurrences is limited to a short interval in relation to life span. In both sets of observations, as well as in other test systems of carcinogenesis, the peak of occurrence or the mean latent period is roughly inversely related to Dsup(-1/3). Applied to lung tumours and leukaemia, the spread of cases about the peak incidence was found to be typically less than a fifth of the life span. Exposure risks do not continue to act over life span. Neoplastic disease risk from carcinogens levels too low to be tested experimentally, theoretically usually lies beyond the life span. The social and economic consequences of a theoretically calculated number of deaths due to those

  20. Importance of dose-rate and cell proliferation in the evaluation of biological experimental results

    Science.gov (United States)

    Curtis, S. B.

    1994-01-01

    The nuclei of cells within the bodies of astronauts traveling on extended missions outside the geomagnetosphere will experience single traversals of particles with high Linear Energy Transfer (LET) (e.g., one iron ion per one hundred years, on average) superimposed on a background of tracks with low LET (approximately one proton every two to three days, and one helium ion per month). In addition, some cell populations within the body will be proliferating, thus possibly providing increasing numbers of cells with 'initiated' targets for subsequent radiation hits. These temporal characteristics are not generally reproduced in laboratory experimental protocols. Implications of the differences in the temporal patterns of radiation delivery between conventionally designed radiation biology experiments and the pattern to be experienced in space are examined and the importance of dose-rate and cell proliferation are pointed out in the context of radiation risk assessment on long mission in space.

  1. Effective dose from inhaled radon and its progeny

    International Nuclear Information System (INIS)

    Currently, the International Commission on Radiological Protection (ICRP) uses the dose conversion convention to calculate effective dose per unit exposure to radon and its progeny. In a recent statement, ICRP indicated the intention that, in future, the same approach will be applied to intakes of radon and its progeny as is applied to all other radionuclides, calculating effective dose using reference biokinetic and dosimetric models, and radiation and tissue weighting factors. Effective dose coefficients will be given for reference conditions of exposure. In this paper, preliminary results of dose calculations for Rn-222 progeny are presented and compared with values obtained using the dose conversion convention. Implications for the setting of reference levels are also discussed.

  2. MCNP Code in Assessment of Variations of Effective Dose with Torso Adipose Tissue Thickness

    International Nuclear Information System (INIS)

    The effective dose is the unite used in the field of radiation protection. It is a well defined doubly weighted uantity involving both physical and biological variables. Several factors may induce variation in the effective dose in different individuals of similar exposure data. One of these factors is the variation of adipose tissue thickness in different exposed individuals. This study essentially concenrs the assessment of the possible variation in the effective dose due to variation in the thickness of adipose tissue. The study was done using MCNP4b code to perform mathematical model of the human body depending on that given to the reference man developed by International Commission of Radiological Protection (ICRP), and calculate the effective dose with different thicknessess of adipose tissues. The study includes a comprehensive appraisal of the Monte Cario simulation, the Medical Internal Radiation Dose (MIRD) model for the human body, and the various mathematical considerations involved in the radiation dose calculations for the various pertinent parts of the human body. The radiation energies considered were 80 KeV, 300 KeV and I MeV, applying two exposure positions; anteroposterior (AP), postero-anterior (PA) with different adipose tissue thickness. This study is a theoretical approach based on detailed mathematical calculations of great precision that deals with all considerations involved in the mechanisms of radiation energy absorption in biological system depending on the variation in the densities of the particular in biological system depending on the variation in the densities of the particular tissues. The results obtained indicate that maximum decrease in effective dose occures with the lowest energy at 5cm adipose tissues thickeness for both AP and PA exposure positions. The results obtained were compared to similar work previsouly done using MCNP4 b showing very good agreement

  3. A study of the correlation between dose area product and effective dose in vascular radiology

    International Nuclear Information System (INIS)

    The purpose of the multi-centre study was to assess dose area product (DAP) and effective dose of patients undergoing angiography of the lower limbs in Belgium and to investigate the correlation between DAP and effective dose. DAP values were measured in 12 centres and compared with the national diagnostic reference levels (DRLs). The effective dose (E) was estimated by multiplying the DAP with case-specific conversion coefficients (CCs) that were calculated with Monte Carlo software MCNP5. As a model for the patient, a mathematical hermaphrodite phantom was used. Calculations showed that tube configurations and extra Cu filtration have a large influence on these CCs. Due to the use of Cu filtration, effective dose can be twice as high for comparable DAP values. Also the use of an over-couch tube configuration is a disadvantage when compared with the under-couch tube configuration. For centres working under-couch without the use of extra Cu-filtration, the DAP values correlate very well with effective dose (Spearman's rank correlation ρ = 0.97). For these conditions, general CCs between DAP and E were calculated. They were 0.083 mSv Gy-1 cm-2 (ICRP 60) and 0.065 mSv Gy-1 cm-2 (ICRP 103). (authors)

  4. Survey of effective dose levels from typical paediatric CT protocols

    International Nuclear Information System (INIS)

    Concern over reported large radiation doses leading to a high cancer risk for paediatric CT patients has prompted considerable investigation in paediatric CT. The recent release of software from Germany has allowed effective doses to be calculated from CT protocol information and radiation measurement for standard paediatric patient sizes for both sexes. An initial study has been undertaken in nine radiology departments, four of which were dedicated paediatric departments, for routine chest and abdominal CT procedures. The dose calculation software is based on Monte Carlo simulation of X-ray conditions during a CT procedure and utilized a 'tomographic' phantom model of a 7-year-old child and an 8-week-old baby to allow calculation of organ dose and hence effective dose. Results of the survey indicate that effective doses were higher for females than males, and higher for abdominal procedures. Slightly higher effective doses were calculated for the child compared to the baby. All centres but one recorded lower effective doses with their current protocols than if they had used recommended CT protocols found in the literature. Analysis of the survey data indicates that scan parameters are the main cause of dose variations, although the type of scanner can affect dose by a factor of 2 (when comparing different units) as well as variation in anatomy scanned in protocols. Dose reduction appears to be most closely linked with reduced mAs and increased pitch as expected. The calculation of effective dose appears to be a key factor in assessing CT protocols, particularly for paediatric patients. Copyright (2003) Blackwell Science Pty Ltd

  5. Frequency and collective effective dose equivalent of medical exposures

    International Nuclear Information System (INIS)

    According to ICRP recommendation, medical exposure refers to the intentional exposure of patients for diagnostic and therapeutic purposes, and to the exposures resulting from the artificial replacement of body organs or functions. Since the objective of radiotherapy is to give a large amount of radiation dose to the patient to kill cancer cells, neither individual nor collective effective doses are directly relevant for comparisons with doses from other sources, not even with diagnostic procedures. For this reason, in present report, therapeutic uses of radiations and radiopharmaceuticals are not included in the medical exposures. Medical exposures in Japan have been investigated by the nationwide surveys on the type and the frequency of radiological procedures and by the dose determinations with phantom experiments or calculations since 1960. Present report reviews the frequency of diagnostic radiological procedures and the collective effective dose equivalents from these procedures, and excess deaths from the medical exposures in Japan. In 1986, the number of X-ray diagnostic examinations was estimated to be about 1.41 x 108. The preliminary result in 1991 shows the number will be about 1.8 x 108. The resultant collective effective dose equivalent from X-ray diagnosis in 1986 was about 1.84 x 105 person Sv. Consequently per Caput mean effective dose equivalent was about 1.48 mSv/person in 1986. The total collective effective dose equivalent from all the diagnostic radiological procedures in Japan was estimated to be about 2.96 x 105 person Sv/year. per Caput mean effective dose equivalent from the total diagnostic radiological procedures in Japan was evaluated to be about 2.3 mSv/year. This value may be comparable to the mean annual effective dose equivalent received from natural radiations for the worldwide population. Mean effective dose equivalent per diagnostic radiological examination was calculated to be about 1.00 mSv/examination. (author)

  6. Determining effective radiation mutagen dose for garlic (Allium sativum L.)

    International Nuclear Information System (INIS)

    This study was carried out to get database for future garlic mutation breeding studies. For this aim, 0, 5, 10, 15, 20, 25 and 30 Gy doses of Cs137 (gamma-ray) were applied on garlic cloves as a physical mutagen. 50 cloves were used for each dose. Sixty days after treatment, germination rate and shoot development of cloves were determined. The Effective Mutagen Dose (ED50) was calculated by regression analyses. According to the results, 4.455 Gy dose was found to be effective as ED50. (author)

  7. Effective dose from direct and indirect digital panoramic units

    International Nuclear Information System (INIS)

    This study aimed to provide comparative measurements of the effective dose from direct and indirect digital panoramic units according to phantoms and exposure parameters. Dose measurements were carried out using a head phantom representing an average man (175 cm tall, 73.5 kg male) and a limbless whole body phantom representing an average woman (155 cm tall, 50 kg female). Lithium fluoride thermoluminescent dosimeter (TLD) chips were used for the dosimeter. Two direct and 2 indirect digital panoramic units were evaluated in this study. Effective doses were derived using 2007 International Commission on Radiological Protection (ICRP) recommendations. The effective doses of the 4 digital panoramic units ranged between 8.9 μSv and 37.8 μSv. By using the head phantom, the effective doses from the direct digital panoramic units (37.8 μSv, 27.6 μSv) were higher than those from the indirect units (8.9 μSv, 15.9 μSv). The same panoramic unit showed the difference in effective doses according to the gender of the phantom, numbers and locations of TLDs, and kVp. To reasonably assess the radiation risk from various dental radiographic units, the effective doses should be obtained with the same numbers and locations of TLDs, and with standard hospital exposure. After that, it is necessary to survey the effective doses from various dental radiographic units according to the gender with the corresponding phantom.

  8. Effective dose from direct and indirect digital panoramic units

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Gun Sun; Kim, Jin Soo; Seo, Yo Seob; Kim, Jae Duk [School of Dentistry, Oral Biology Research Institute, Chosun University, Gwangju (Korea, Republic of)

    2013-06-15

    This study aimed to provide comparative measurements of the effective dose from direct and indirect digital panoramic units according to phantoms and exposure parameters. Dose measurements were carried out using a head phantom representing an average man (175 cm tall, 73.5 kg male) and a limbless whole body phantom representing an average woman (155 cm tall, 50 kg female). Lithium fluoride thermoluminescent dosimeter (TLD) chips were used for the dosimeter. Two direct and 2 indirect digital panoramic units were evaluated in this study. Effective doses were derived using 2007 International Commission on Radiological Protection (ICRP) recommendations. The effective doses of the 4 digital panoramic units ranged between 8.9 {mu}Sv and 37.8 {mu}Sv. By using the head phantom, the effective doses from the direct digital panoramic units (37.8 {mu}Sv, 27.6 {mu}Sv) were higher than those from the indirect units (8.9 {mu}Sv, 15.9 {mu}Sv). The same panoramic unit showed the difference in effective doses according to the gender of the phantom, numbers and locations of TLDs, and kVp. To reasonably assess the radiation risk from various dental radiographic units, the effective doses should be obtained with the same numbers and locations of TLDs, and with standard hospital exposure. After that, it is necessary to survey the effective doses from various dental radiographic units according to the gender with the corresponding phantom.

  9. Relative biological effectiveness (RBE) of fission neutrons and gamma rays at occupational exposure levels

    International Nuclear Information System (INIS)

    The pathologic consequences of exposure to 60 equal once-weekly doses of fission neutron or 60Co gamma rays have been subjected to dose-response analyses for the purposes of generating relative biological effectiveness (RBE) values for the major causes of death of for tumor occurrences. Cumulative probabilities of death or occurrence were generated for 15 categories of neoplastic disease for the time interval of 800--999 days since first exposure. These probabilities were developed for each dose, sex, and radiation quality, and a dose-response analysis was applied to derive linear risk coefficients of death or occurrence. 40 refs., 16 figs., 9 tabs

  10. Biological dosimetry - a Bayesian approach in the presentation of the uncertainty of the estimated dose in cases of exposure to low dose radiation

    International Nuclear Information System (INIS)

    Biodosimetry laboratory experience has shown that there are limitations in the existing statistical methodology. Statistical difficulties generally occur due to the low number of aberrations leading to large uncertainties for dose estimation. Some problems derived from limitations of the classical statistical methodology, which requires that chromosome aberration yields be considered as something fixed and consequently provides a deterministic dose estimation and associated confidence limits. On the other hand, recipients of biological dosimetry reports, including medical doctors, regulators and the patients themselves may have a limited comprehension of statistics and of informed reports. Thus, the objective of the present paper is to use a Bayesian approach to present the uncertainty on the estimated dose to which a person could be exposed, in the case of low dose (occupational doses) radiation exposure. Such methodology will allow the biodosimetrists to adopt a probabilistic approach for the cytogenetic data analysis. At present, classical statistics allows to produce a confidence interval to report such dose, with a lower limit that could not detach from zero. In this situation it becomes difficult to make decisions as they could impact on the labor activities of the worker if an exposure exceeding the occupational dose limits is inferred. The proposed Bayesian approach is applied to occupational exposure scenario to contribute to take the appropriate radiation protection measures. (authors)

  11. Committed equivalent organ doses and committed effective doses from intakes of radionuclides

    International Nuclear Information System (INIS)

    NRPB has published a software package, NRPB-SR245, which contains the most recent data on doses per unit intake of radionuclides. The data incorporates the new ICRP recommendations on tissue weighting factors and current NRPB advice on gut transfer factors. The software package lists the committed effective doses for ingestion and inhalation of 1 μm AMAD particles of 359 nuclides by infants aged 3 months, by children aged 1, 5, 10 and 15 years and by adults, together with the highest committed equivalent organ dose. The software package is available from NRPB Information Services, price Pound 50.00 + VAT. (author)

  12. Mechanistic Effects of Calcitriol in Cancer Biology

    Directory of Open Access Journals (Sweden)

    Lorenza Díaz

    2015-06-01

    Full Text Available Besides its classical biological effects on calcium and phosphorus homeostasis, calcitriol, the active vitamin D metabolite, has a broad variety of actions including anticancer effects that are mediated either transcriptionally and/or via non-genomic pathways. In the context of cancer, calcitriol regulates the cell cycle, induces apoptosis, promotes cell differentiation and acts as anti-inflammatory factor within the tumor microenvironment. In this review, we address the different mechanisms of action involved in the antineoplastic effects of calcitriol.

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

    Energy Technology Data Exchange (ETDEWEB)

    Strom, Daniel J.

    2008-04-14

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

  14. Adaptive response and split-dose effect of radiation on the survival of mice

    Indian Academy of Sciences (India)

    Ashu Bhan Tiku; R K Kale

    2004-03-01

    Although the importance of radiation-induced adaptive response has been recognized in human health, risk assessment and clinical application, the phenomenon has not been understood well in terms of survival of animals. To examine this aspect Swiss albino mice were irradiated with different doses (2–10 Gy) at 0.015 Gy/s dose rate and observed on a regular basis for 30 days. Since almost 50% lethality was seen with 8 Gy, it was selected as the challenging dose for further studies. Irradiation of mice with conditioning doses (0.25 or 0.5 Gy) and subsequent exposure to 8 Gy caused significant increase in the survival of mice compared to irradiated control. The splitting of challenging dose did not influence the efficiency of conditioning doses (0.25 Gy and 0.5 Gy) to induce an adaptive response. However conditioning doses given in fractions (0.25 Gy + 0.25 Gy) or (0.5 Gy + 0.5 Gy) were able to modulate the response of challenging dose of 8 Gy. These results clearly showed the occurrence of adaptive response in terms of survival of animals. The conditioning dose given in small fractions seemed to be more effective. The findings have been discussed from a mechanistic point of view. The possible biological implications, potential medical benefits, uncertainties and controversies related to adaptive response have also been addressed.

  15. Comparison in the determination of absorbed dose by biological and physical methods to patients in treatment of cardiac intervention

    International Nuclear Information System (INIS)

    The use of less invasive procedures, lower risk and quick recovery as cardiac intervention have proven to be an efficient alternative to reestablish the correct bloodstream of the patient. In this case the patient is subjected to values of absorbed dose above to which is subjected in a study with X-rays for medical diagnosis, and this can cause radiation injuries to the skin. The target organ, in this case can be exposed to doses of 2 Gy above. Different methods to estimate the dose were use, physical by Radiochromic film, as biological by dicentric analysis. Both methods provided additional information demonstrating thus the risk in the target organ and the patient. The most reliable biological indicator of exposure to ionizing radiation is the study of chromosomal aberrations, specifically dicentric in human lymphocytes. This test allowed establishing the exposure dose depending of the damage. (Author)

  16. Effects of Low Dose Radiation on Mammals 1

    OpenAIRE

    Okumura, Yutaka; Mine, Mariko; Kishikawa, Masao

    1991-01-01

    Radiation has been applied widely to clinics, researches and industries nowadays. Irradiation by atomic bomb produced many victims in Hiroshima and Nagasaki. Radiation effects on animals and human belings have been reported extensively, especially at a dose range of high amount of radiation. As radiation effects at low dose have not been well studied, it is believed that even a small amount of radiation produces hazardous effects. However, it might not be true. Beneficial effects of a low dos...

  17. Studies of health effects of low dose radiation and its application to medicare

    International Nuclear Information System (INIS)

    The articles contain following 7 topics of low dose radiation effects. Studies of Health Effects of Low dose Radiation and Its Application to Medicare'', describes the indication of Rn therapy and investigations of its usefulness mechanism mainly in Misasa Spa, Okayama Pref. ''Challenges for the Paradigm Shift (CRIEPI Studies)'', introduces studies against the paradigm that radiation dose is linearly and proportionally hazardous. ''Studies of High Background Radiation Area (CRIEPI Studies)'', describes global HBRA studies on chromosome affection and effect of smoking in HBRA. ''Is the Radiation Effect on Man Proportional to Dose? (CRIEPI Studies)'', describes studies of immature sperm irradiated at low dose against Linear-Non-threshold Theory (LNT) hypothesis. ''Induction of Radiation Resistance by Low Dose Radiation and Assessment of Its Effect in Models of Human Diseases (CRIEPI Studies)'', explains the adoptive response in radiation effect, suppression of carcinogenesis and immune regulation by previous low dose radiation in the mouse, and improvement of diabetes in the db/db mouse. ''Modulation of Biological Effects of Low Dose Radiation: Adoptive Response, Bystander Effect, Genetic Instability and Radiation Hormesis'', summarizes findings of each item. ''Cancer Treatment with Low dose Radiation to the Whole Body'', describes basic studies in the mouse tumor in relation to suppression of carcinogenesis and metastasis, immune activation and treatment, and successful clinical studies in patients with ovary, colon cancers and malignant lymphoma where survival has been significantly improved: a base of recent European Organization for Research and Treatment of Cancer (EORTC) clinical trials. The mechanism is essentially based on immune activation of patients to cure the disease. (R.T.)

  18. THz waves: biological effects, industrial and medical

    International Nuclear Information System (INIS)

    Following the debates about body scanners installed in airports for passengers security control, the non-ionizing radiations (NIR) section of the French radiation protection society (SFR) has organized a conference day to take stock of the present day knowledge about the physical aspects and the biological effects of this frequency range as well as about their medical, and industrial applications (both civil and military). This document gathers the slides of the available presentations: 1 - introduction and general considerations about THz waves, the THz physical phenomenon among NIR (J.L. Coutaz); 2 - interaction of millimeter waves with living material: from dosimetry to biological impacts (Y. Le Drean and M. Zhadobov); 3 - Tera-Hertz: standards and recommendations (B. Veyret); 4 - THz spectro-imaging technique: status and perspectives (P. Mounaix); 5 - THz technology: seeing the invisible? (J.P. Caumes); 6 - Tera-Hertz: biological and medical applications (G. Gallot); 7 - Biological applications of THz radiation: a review of events and a glance to the future (G.P. Gallerano); 8 - Industrial and military applications - liquids and solids detection in the THz domain (F. Garet); 9 - THz radiation and its civil and military applications - gas detection and quantifying (G. Mouret); 10 - Body scanners and civil aviation security (J.C. Guilpin, presentation not available). (J.S.)

  19. Assessment of organ equivalent doses and effective doses from diagnostic X-ray examinations

    International Nuclear Information System (INIS)

    The MIRD-type adult male, female and age 10 phantoms were constructed to evaluate organ equivalent dose and effective dose of patient due to typical diagnostic X-ray examination. These phantoms were constructed with external and internal dimensions of Korean. The X-ray energy spectra were generated with SPEC78. MCNP4B ,the general-purposed Monte Carlo code, was used. Information of chest PA , chest LAT, and abdomen AP diagnostic X-ray procedures was collected on the protocol of domestic hospitals. The results showed that patients pick up approximate 0.02 to 0.18 mSv of effective dose from a single chest PA examination, and 0.01 to 0.19 mSv from a chest LAT examination depending on the ages. From an abdomen AP examination, patients pick up 0.17 to 1.40 mSv of effective dose. Exposure time, organ depth from the entrance surface and X-ray beam field coverage considerably affect the resulting doses. Deviation among medical institutions is somewhat high, and this indicated that medical institutions should interchange their information and the need of education for medical staff. The methodology and the established system can be applied, with some expansion, to dose assessment for other medical procedures accompanying radiation exposure of patients like nuclear medicine or therapeutic radiology

  20. Chest X ray effective doses estimation in computed radiography

    International Nuclear Information System (INIS)

    Conventional chest radiography is technically difficult because of wide in tissue attenuations in the chest and limitations of screen-film systems. Computed radiography (CR) offers a different approach utilizing a photostimulable phosphor. photostimulable phosphors overcome some image quality limitations of chest imaging. The objective of this study was to estimate the effective dose in computed radiography at three hospitals in Khartoum. This study has been conducted in radiography departments in three centres Advanced Diagnostic Center, Nilain Diagnostic Center, Modern Diagnostic Center. The entrance surface dose (ESD) measurement was conducted for quality control of x-ray machines and survey of operators experimental techniques. The ESDs were measured by UNFORS dosimeter and mathematical equations to estimate patient doses during chest X rays. A total of 120 patients were examined in three centres, among them 62 were males and 58 were females. The overall mean and range of patient dosed was 0.073±0.037 (0.014-0.16) mGy per procedure while the effective dose was 3.4±01.7 (0.6-7.0) mSv per procedure. This study compared radiation doses to patients radiographic examinations of chest using computed radiology. The radiation dose was measured in three centres in Khartoum- Sudan. The results of the measured effective dose showed that the dose in chest radiography was lower in computed radiography compared to previous studies.(Author)

  1. Scientific projection paper on biologic effects of ionizing radiation

    International Nuclear Information System (INIS)

    There is widespread knowledge about the effects of radiation in human populations but the studies have had some limitations which have left gaps in our knowledge. Most populations have had exposure to high doses with little information on the effect of dose rate. The characteristics of the populations have been restricted by the location of the disaster, the occupational limitations, or the basic risks associated with the under-lying disease for which radiation was given. All doses have been estimated and such values are subject to marked variability particularly when they rely on sources of data such as hospital records. The biological data although extensive have several deficits in information. Which are the sites in which cancer is produced by irradiation and what are the cell types which are produced. The sensitivity of various tissues and organs are not similar and it is important to rank them according to susceptibility. This has been done in the past but the results are not complete for all cell types and organs. The temporal patterns for tumor development, the latent period, the period of expressed excess, the life-time risks need to be defined more precisely for the cancers. Many populations have not been followed long enough to express the complete risk

  2. TLD estimation of absorbed dose for 131I on the surface of biological organs of REMCAL phantom

    International Nuclear Information System (INIS)

    In nuclear medicine, the accuracy of absorbed dose of an internally distributed radiopharmaceuticals estimated by the MIRD (medical internal radiation dose) method depends on the cumulated activity of the source organs and their mass. The usual method for obtaining the cumulated activities are: 1) direct measurements by a) positron emission tomography (PET) and b) single photon emission computed tomography (SPECT) 2) extrapolation from animal data and 3) calculations based on the mathematical biokinetic model. Among these methods, extrapolation of animal data to humans includes inevitable inaccuracy due to large interspecies metabolic differences with regard to the administered radiochemical. Biokinetic modeling requires adequate knowledge of various kinetic parameters, which is based on some biological assumptions. Direct measurements can provide cumulated distributions with fewer biological assumptions. But direct measurements of PET/SPECT are difficult to perform routinely. A method has been developed to obtain the surface dose of different biological organs by using TLDs. Here, a number of TLDs are placed just above the surface of the biological organs of the REMCAL Alderson human phantom filled with water. Firstly, investigation of the accuracy of this method by calibration studies using the said phantom, which is having the entire biological organ intact and simulate the organs as human body is done. These organs are filled with the known activity of the radioisotope. In the present study, estimation of radiation dose received by fifteen different target organs, when the known activity was filled in the three major organs of interest was carried out

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

    International Nuclear Information System (INIS)

    Objective: To study the effect of traditional method and improved method of the premature chromosome condensation (PCC) on the dose-effect curve of 60Co 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 60Co 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, P0.05), 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)

  4. A Method of Biological Measurement of Thermal- and Fast-Neutron Doses Absorbed by Living Organisms

    International Nuclear Information System (INIS)

    After exposing young rats to a high thermal neutron flux the activated zones were determined by autoradiography at -195°C. The localization and nature of some of the activated elements were studied. Attention is drawn to the important role of P32 compared to other activation products. The authors compare the doses resulting from direct exposure to the neutron flux with those associated with local irradiation of bone and other tissue as a secondary effect of activation. The next step will be to study the possibility of using micro biopsy of bone tissue as a precise means of evaluating absorbed-neutron dose a posteriori in terms of different parts of the organism and different neutron energies. (Measurement of the samples specific P32 activity for thermal neutrons and calculation of the specific Si31 activity for fast neutrons). (author)

  5. Collective effective dose from diagnostic radiology in Ukraine

    International Nuclear Information System (INIS)

    The frequencies and effective doses for the most common X-ray diagnostic examinations in Ukraine were assessed in the frame of the European Commission (EC) Study on European Population Doses from Medical Exposure (Dose Datamed 2). The average effective doses for all radiographic procedures were estimated using the ODS-60 software (Finland). The estimation of the effective doses for the chest film fluorography was carried out from the results of own representative measurements with thermoluminescent (TL) dosimetry and a standard Alderson-Rando phantom. The effective doses for fluoroscopy procedures were assessed using the Russian guidelines for estimation of effective doses. For all other X-ray examinations and procedures [computed tomography (CT), angiography and interventional procedures], typical effective dose values were taken from the EC Guidance RP154. The most frequently performed in Ukraine is chest film fluorography, with 389 examinations per 1000 population annually, reflecting in the greatest contribution to the total collective effective dose (CED) of 428 mSv per 1000 population (44 %). The total frequency and CED from all X-ray diagnostic examinations and procedures were estimated to be 1218 examinations and 1060 mSv per 1000 populations, respectively. The expected additional cancer risk from X-ray diagnostic examinations and interventional procedures is 2680 cases per year, with 1200 of them due to the contribution of chest fluorography. The main important action in radiation protection of patients in diagnostic radiology is the organisation of the monitoring of patient doses for different types of X-ray diagnostic examinations and replacement of chest film fluorography with digital X-ray systems. (authors)

  6. Committed effective doses at various times after intakes of radionuclides

    CERN Document Server

    Phipps, A W; Kendall, G M; Silk, T J; Stather, J W

    1991-01-01

    This report contains details of committed effective doses at nine times after intake from intakes by ingestion and inhalation of 1 mu 1 AMAD particles by adults. Data are given for various chemical forms of 359 nuclides. It complements NRPB-R245 which describes the changes which have taken place since the last NRPB compendium of dose per unit intake factors (dose coefficients) and gives summary tables. Information on committed equivalent doses to organs is given in NRPB-M288. The information given in these memoranda is also available as a microcomputer package - NRPB-SR245.

  7. Threshold dose effect in FXG gels: real or apparent?

    Science.gov (United States)

    Babic, S.; Battista, J.; Jordan, K.

    2006-12-01

    The purpose of this present study was to identify the chemical and or physical mechanism responsible for the threshold dose effect in ferrous xylenol orange gelatin gels and to control it in order to achieve better reproducibility and reliable calibration across the entire linear dose range.

  8. Radiation Dose-Volume Effects in the Lung

    International Nuclear Information System (INIS)

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

  9. Radiation dose-volume effects in the lung

    DEFF Research Database (Denmark)

    Marks, Lawrence B; Bentzen, Soren M; Deasy, Joseph O;

    2010-01-01

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

  10. What can we say about the dose-effect relationship at very low doses?

    International Nuclear Information System (INIS)

    This paper uses a few sets of low-dose experimental radiobiological data to examine just what these data sets say with respect to the shape of the dose-effect relationship at very low doses. The examination of the data leads to the conclusion that neither experimental nor epidemiological data will ever be statistically strong enough to resolve the debate unambiguously. An alternative approach to the low-dose problem is proposed based on gaining a deeper understanding of both the mechanism of action of radiation and the cellular changes which lead to malignancy. Research spending needs to be directed to more basic investigations of radiation action and to ways by which the information from these studies can be applied to the interpretation of epidemiological data. (author)

  11. Organ doses and effective doses in some medical and industrial applications

    International Nuclear Information System (INIS)

    The ICRP recommends radiation protection standards for the safe use of radiation and also prescribes the radiation protection quantities and periodically reviews them. In this context, the quantities like organ doses and effective doses are defined by ICRP. In this work we calculate these quantities and hence the conversion functions for the industrial radiation sources and those for CT and diagnostic X-ray exposures. Workers who are occupationally exposed to radiation are regularly monitored to evaluate the radiation dose received by them. It is quite possible that in an accident situation, the worker involved in the accident might not have worn a personal monitor, popularly known as the monitoring badge. In addition, even some non radiation workers (who are obviously not monitored) may also have received exposure. Under these circumstances, the persons involved are interviewed, the accident site inspected, and on the basis of realistic assumptions, the likely doses received by the exposed persons are estimated

  12. Establishment of a semi-biological phantom model for the study of the effect of dose reducing measures on radiation-induced DNA double strand breaks in CT using the example of risk organ based tube current modulation; Etablierung eines semibiologischen Phantommodells zur Untersuchung des Effekts dosisreduzierender Massnahmen auf strahleninduzierte DNA-Doppelstrangbrueche in der CT am Beispiel der risikoorganbasierten Roehrenstrommodulation

    Energy Technology Data Exchange (ETDEWEB)

    Sommer, Matthias

    2013-12-12

    The number of computed tomography (CT) examinations has been rising during the last decades. Therefore techniques for dose reduction receive increasing attention. Risk organ-based tube current modulation (RCM) in CT is a new approach and works by lowering the tube current, while the tube is in front of the patient's body. Therefore it should lead to a dose reduction for radiosensitive organs like the female breast, the eye lenses and the thyroid gland. Biological radiation effects cannot be estimated by physical-based dose measurements. γ-H2AX is a sensitive marker for the determination of x-ray induced DNA double-strand breaks (DSB). Hence the aim of this study was to establish a biological phantom model based on the γ-H2AX immunofluorescence microscopy method and to investigate the effect of RCM on radiation induced DNA damages. The γ-H2AX method is based on the phosphorylation of the histone variant H2AX. The phosphorylated histone γ-H2AX can be visualised using antibodies and is specific for radiation induced DSB. Blood lymphocytes from healthy volunteers, skin fibroblasts (LN) and mammary epithelial cells (HMEpC-p) were placed in different positions of an Alderson-phantom and exposed to x-rays using a 128-slice dual-source CT scanner. Standard head, neck and chest-CT scan protocols either with or without risk-organ based tube current modulation were used. RCM reduces the tube current to 20 percent at an angle of 130 degree anterior to the body, whereas tube current is increased at an angle of 230 degree posterior to the body. Afterwards cells were isolated, fixed on slides und stained with specific primary γ-H2AX antibodies and fluorescent secondary antibodies. Tiny green dots (named foci) can be detected and quantified with a fluorescence microscope and represent distinct DSB. Non-irradiated samples served as controls and CT-induced DSB were calculated by subtraction of pre- from post-exposure values. In this study a semibiological phantom model

  13. Microwave radiation - Biological effects and exposure standards

    Energy Technology Data Exchange (ETDEWEB)

    Lindsay, I.R.

    1980-06-01

    The thermal and nonthermal effects of exposure to microwave radiation are discussed and current standards for microwave exposure are examined in light of the proposed use of microwave power transmission from solar power satellites. Effects considered include cataractogenesis at levels above 100 mW/sq cm, and possible reversible disturbances such as headaches, sleeplessness, irritability, fatigue, memory loss, cardiovascular changes and circadian rhythm disturbances at levels less than 10 mW/sq cm. It is pointed out that while the United States and western Europe have adopted exposure standards of 10 mW/sq cm, those adopted in other countries are up to three orders of magnitude more restrictive, as they are based on different principles applied in determining safe limits. Various aspects of the biological effects of microwave transmissions from space are considered in the areas of the protection of personnel working in the vicinity of the rectenna, interactions of the transmitted radiation with cardiac pacemakers, and effects on birds. It is concluded that thresholds for biological effects from short-term microwave radiation are well above the maximal power density of 1 mW/sq cm projected at or beyond the area of exclusion of a rectenna.

  14. On the biological basis for competing macroscopic dose descriptors for kilovoltage dosimetry: cellular dosimetry for brachytherapy and diagnostic radiology

    Science.gov (United States)

    Thomson, R. M.; Carlsson Tedgren, Å.; Williamson, J. F.

    2013-02-01

    The purpose of this work is to investigate how alternative macroscopic dose descriptors track absorbed dose to biologically relevant subcellular targets via Monte Carlo (MC) analysis of cellular models for a variety of cancerous and normal soft tissues for kilovoltage radiation. The relative mass distributions of water, light inorganic elements, and protein components of nuclear and cytoplasm compartments for various tissues are determined from a literature review. These data are used to develop representative cell models to demonstrate the range of mass elemental compositions of these subcellular structures encountered in the literature from which radiological quantities (energy absorption and attenuation coefficients; stopping powers) are computed. Using representative models of cell clusters, doses to subcellular targets are computed using MC simulation for photon sources of energies between 20 and 370 keV and are compared to bulk medium dose descriptors. It is found that cells contain significant and varying mass fractions of protein and inorganic elements, leading to variations in mass energy absorption coefficients for cytoplasm and nuclear media as large as 10% compared to water for sub-50 keV photons. Doses to subcellular structures vary by as much as 23% compared to doses to the corresponding average bulk medium or to small water cavities embedded in the bulk medium. Relationships between cellular target doses and doses to the bulk medium or to a small water cavity embedded in the bulk medium are sensitive to source energy and cell morphology, particularly for lower energy sources, e.g., low energy brachytherapy (water or the corresponding average bulk tissue. For kilovoltage photon sources, neither dose to bulk medium nor dose to water quantitatively tracks energy imparted to biologically relevant subcellular targets for the range of cellular morphologies and tissues considered.

  15. Effective dose and cancer risk in PET/CT exams

    International Nuclear Information System (INIS)

    Due to the use of radiopharmaceutical positron-emitting in PET exam and realization of tomography by x-ray transmission in CT examination, an increase of dose with hybrid PET/CT technology is expected. However, differences of doses have been reported in many countries for the same type of procedure. It is expected that the dose is an influent parameter to standardize the protocols of PET/CT. This study aimed to estimate the effective doses and absorbed in 65 patients submitted to oncological Protocol in a nuclear medicine clinic in Rio de Janeiro, considering the risk of induction of cancer from the scan. The CT exam-related doses were estimated with a simulator of PMMA and simulated on the lmPACT resistance, which for program effective dose, were considered the weight factors of the lCRP 103. The PET exam doses were estimated by multiplying the activity administered to the patient with the ICRP dose 80 factors. The radiological risk for cancer incidence were estimated according to the ICRP 103. The results showed that the effective dose from CT exam is responsible for 70% of the effective total in a PET/CT scan. values of effective dose for the PET/CT exam reached average values of up to 25 mSv leading to a risk of 2, 57 x 10-4. Considering that in staging of oncological diseases at least four tests are performed annually, the total risk comes to 1,03x 10-3

  16. The biological effects of radium-224 injected into dogs

    International Nuclear Information System (INIS)

    A life-span study was conducted in 128 beagle dogs to determine the biological effects of intravenously injected 224Ra chloride. The 224Ra chloride was prepared by the same method used for intravenous injections in humans who were treated for ankylosing spondylitis and tuberculosis. Thus the results obtained from dogs can be compared directly to the population of treated humans, both for the elucidation of the effect of exposure rate and for comparison with other radionuclides for which data for humans are unavailable. Using equal numbers of males and females, the dogs were injected with one of four levels of 224Ra resulting in initial body burdens of approximately 13, 40, 120 or 350 kBq of 224Ra kg-1 body mass. A control group of dogs was injected with diluent only. All dogs were divided further into three groups for which the amount of injected 224Ra (half-life of 3.62 days) or diluent was given in a single injection or divided equally into 10 or 50 weekly injections. As a result of these three injection schedules, the accumulation of dose from the injected 224Ra was distributed over approximately 1, 3 or 12 months. Each injection schedule included four different injection levels resulting in average absorbed α-particle doses to bone of 0.1, 0.3, 1 and 3 Gy, respectively. The primary early effect observed was a hematological dyscrasia in the dogs receiving either of the two highest injection levels. The effect was most severe in the dogs receiving a single injection of 224Ra and resulted in the death of three dogs injected at the highest level. The late-occurring biological effects were tumors. Bone tumors were the most common followed by tumors in the nasal mucosa. 52 refs., 8 figs., 8 tabs

  17. Adult head CT scans: the uncertainties of effective dose estimates

    International Nuclear Information System (INIS)

    Full Text: CT scanning is a high dose imaging modality. Effective dose estimates from CT scans can provide important information to patients and medical professionals. For example, medical practitioners can use the dose to estimate the risk to the patient, and judge whether this risk is outweighed by the benefits of the CT examination, while radiographers can gauge the effect of different scanning protocols on the patient effective dose, and take this into consideration when establishing routine scan settings. Dose estimates also form an important part of epidemiological studies examining the health effects of medical radiation exposures on the wider population. Medical physicists have been devoting significant effort towards estimating patient radiation doses from diagnostic CT scans for some years. The question arises: How accurate are these effective dose estimates? The need for a greater understanding and improvement of the uncertainties in CT dose estimates is now gaining recognition as an important issue (BEIR VII 2006). This study is an attempt to analyse and quantify the uncertainty components relating to effective dose estimates from adult head CT examinations that are calculated with four commonly used methods. The dose estimation methods analysed are the Nagel method, the ImpaCT method, the Wellhoefer method and the Dose-Length Product (DLP) method. The analysis of the uncertainties was performed in accordance with the International Standards Organisation's Guide to the Expression of Uncertainty in Measurement as discussed in Gregory et al (Australas. Phys. Eng. Sci. Med., 28: 131-139, 2005). The uncertainty components vary, depending on the method used to derive the effective dose estimate. Uncertainty components in this study include the statistical and other errors from Monte Carlo simulations, uncertainties in the CT settings and positions of patients in the CT gantry, calibration errors from pencil ionization chambers, the variations in the organ

  18. Effective dose estimation to patients and staff during urethrography procedures

    Energy Technology Data Exchange (ETDEWEB)

    Sulieman, A. [Prince Sattam bin Abdulaziz University, College of Applied Medical Sciences, Radiology and Medical Imaging Department, P. O- Box 422, Alkharj 11942 (Saudi Arabia); Barakat, H. [Neelain University, College of Science and Technology, Medical Physics Department, Khartoum (Sudan); Alkhorayef, M.; Babikir, E. [King Saud University, College of Applied Sciences, Radiological Sciences Department, P. O. Box 10219, Riyadh 11433 (Saudi Arabia); Dalton, A.; Bradley, D. [University of Surrey, Centre for Nuclear and Radiation Physics, Department of Physics, Surrey, GU2 7XH Guildford (United Kingdom)

    2015-10-15

    Medical-related radiation is the largest source of controllable radiation exposure to humans and it accounts for more than 95% of radiation exposure from man-made sources. Few data were available worldwide regarding patient and staff dose during urological ascending urethrography (ASU) procedure. The purposes of this study are to measure patient and staff entrance surface air kerma dose (ESAK) during ASU procedure and evaluate the effective doses. A total of 243 patients and 145 staff (Urologist) were examined in three Hospitals in Khartoum state. ESAKs were measured for patient and staff using thermoluminescent detectors (TLDs). Effective doses (E) were calculated using published conversion factors and methods recommended by the national Radiological Protection Board (NRPB). The mean ESAK dose for patients and staff dose were 7.79±6.7 mGy and 0.161±0.30 mGy per procedures respectively. The mean and range of the effective dose was 1.21 mSv per procedure. The radiation dose in this study is comparable with previous studies except Hospital C. It is obvious that high patient and staff exposure is due to the lack of experience and protective equipment s. Interventional procedures remain operator dependent; therefore continuous training is crucial. (Author)

  19. Effective dose estimation to patients and staff during urethrography procedures

    International Nuclear Information System (INIS)

    Medical-related radiation is the largest source of controllable radiation exposure to humans and it accounts for more than 95% of radiation exposure from man-made sources. Few data were available worldwide regarding patient and staff dose during urological ascending urethrography (ASU) procedure. The purposes of this study are to measure patient and staff entrance surface air kerma dose (ESAK) during ASU procedure and evaluate the effective doses. A total of 243 patients and 145 staff (Urologist) were examined in three Hospitals in Khartoum state. ESAKs were measured for patient and staff using thermoluminescent detectors (TLDs). Effective doses (E) were calculated using published conversion factors and methods recommended by the national Radiological Protection Board (NRPB). The mean ESAK dose for patients and staff dose were 7.79±6.7 mGy and 0.161±0.30 mGy per procedures respectively. The mean and range of the effective dose was 1.21 mSv per procedure. The radiation dose in this study is comparable with previous studies except Hospital C. It is obvious that high patient and staff exposure is due to the lack of experience and protective equipment s. Interventional procedures remain operator dependent; therefore continuous training is crucial. (Author)

  20. Topics on study of low dose-effect relationship

    Energy Technology Data Exchange (ETDEWEB)

    Yamada, Takeshi [Toho Univ., School of Medicine, Tokyo (Japan); Ohyama, Harumi

    1999-09-01

    It is not exceptional but usually observed that a dose-effect relationship in biosystem is not linear. Sometimes, the low dose-effect relationship appears entirely contrary to the expectation from high dose-effect. This is called a 'hormesis' phenomena. A high dose irradiation inflicts certainly an injury on biosystem. No matter how low the dose may be, an irradiation might inflict some injury on biosystem according to Linear Non-Threshold hypothesis(LNT). On the contrary to the expectation, a low dose irradiation stimulates immune system, and promotes cell proliferation. This is called 'radiation hormesis'. The studies of the radiation hormesis are made on from four points of view as follows: (1) radiation adaptive response, (2) revitalization caused by a low dose stimulation, (3) a low dose response unexpected from the LNT hypothesis, (4) negation of the LNT hypothesis. The various empirical proofs of radiation hormesis are introduced in the report. (M . Suetake)

  1. Effect of radiation dose on patients' immune response

    International Nuclear Information System (INIS)

    This paper studies the relations between dose delivered and changes in T-cell subsets as an expression of the effect of radiation therapy on patients' immune response. One hundred twenty-eight patients were studied before and 6 weeks after irradiation. Blood samples were analyzed by flow cytometry. A dose effect was noted wherein the OKT4 helper/OKT8 suppressor cell ratio was reduced by more than 10% in 79% of patients receiving a dose greater than 6,000 cGy as compared with 54% of patients given a lower dose (P = .01). Several variables, including sex, age, tumor site, and cancer burden, were analyzed. Male subjects showed a greater reduction of OKT4 helper cells at doses greater than 6,000 cGy-73%, versus 47% in female subjects (P = .05)

  2. Effect of low doses of gamma radiation in tomato seeds

    International Nuclear Information System (INIS)

    Tomato dry seeds of the hybrid 'Gladiador' Fl were exposed to low doses of gamma radiation from 60Co source at 0. 509 kGy tax rate in order to study stimulation effects of radiation on germination and plant growth. Eight treatments of different radiation doses were applied as follows: 0 (control); 2.5, 5.0, 7.5, 10.0, 12.5, 15.0, 20.0 Gy. Seed germination as well as green fruits number, harvested fruit number, fruit weight and total production were assessed to identify occurrence of stimulation. Tomato seeds and plants were handled as for usual tomato production in Brazil. Low doses of gamma radiation treatment in the seeds stimulate germination and substantially increase fruit number and total production up to 86% at 10 Gy dose. There are evidences that the use of low doses of gamma radiation can stimulate germination and plant production thus, showing hormetic effects. (author)

  3. Effects of dose fractionation on the response of alanine dosimetry

    International Nuclear Information System (INIS)

    Alanine dosimetry is well established as a transfer standard and is becoming more prevalently used in routine dosimetry systems for radiation processing. Many routine measurement applications in radiation processing involve absorbed dose measurements resulting from fractioned exposures to ionizing radiation. Fractioning of absorbed dose is identified as an influence quantity (ISO/ASTM, 2013). This paper reports on study results of absorbed dose fractioning characteristics of alanine for gamma and high energy electron beam radiation sources. The results of this study indicate a radiation response difference due to absorbed dose fractioning in response can be observed after four fractionations for high-energy electron beams and no difference up to seven fractions for gamma rays using an ANOVA evaluation method. - Highlights: • Fractioning effects signaled in electron beam using an ANOVA at 6 equal increments. • Fractioning effects not signaled in gamma using an ANOVA up to 7 equal increments. • Insensitivity of alanine to dose fractioning indicates nominal impact on calibration

  4. Topographic Effects on Ambient Dose Equivalent Rates from Radiocesium Fallout

    CERN Document Server

    Malins, Alex; Machida, Masahiko; Saito, Kimiaki

    2015-01-01

    Land topography can affect air radiation dose rates by locating radiation sources closer to, or further, from detector locations when compared to perfectly flat terrain. Hills and slopes can also shield against the propagation of gamma rays. To understand the possible magnitude of topographic effects on air dose rates, this study presents calculations for ambient dose equivalent rates at a range of heights above the ground for varying land topographies. The geometries considered were angled ground at the intersection of two planar surfaces, which is a model for slopes neighboring flat land, and a simple conical geometry, representing settings from hilltops to valley bottoms. In each case the radiation source was radioactive cesium fallout, and the slope angle was varied systematically to determine the effect of topography on the air dose rate. Under the assumption of homogeneous fallout across the land surface, and for these geometries and detector locations, the dose rates at high altitudes are more strongly...

  5. UV-radiation and skin cancer dose effect curves

    International Nuclear Information System (INIS)

    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 1o 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

  6. Radioactive Doses - Predicted and Actual - and Likely Health Effects.

    Science.gov (United States)

    Nagataki, S; Takamura, N

    2016-04-01

    Five years have passed since the nuclear accident at Fukushima Daiichi Nuclear Power Stations on 11 March 2011. Here we refer to reports from international organisations as sources of predicted values obtained from environmental monitoring and dose estimation models, and reports from various institutes in Japan are used as sources of individual actual values. The World Health Organization, based on information available up to 11 September 2011 (and published in 2012), reported that characteristic effective doses in the first year after the accident, to all age groups, were estimated to be in the 10-50 mSv dose band in example locations in evacuation areas. Estimated characteristic thyroid doses to infants in Namie Town were within the 100-200 mSv dose band. A report from the United Nations Scientific Committee on the Effects of Atomic Radiation published in 2014 shows that the effective dose received by adults in evacuation areas during the first year after the accident was 1.1-13 mSv. The absorbed dose to the thyroid in evacuated settlements was 7.2-35 mSv in adults and 15-83 mSv in 1-year-old infants. Individual external radiation exposure in the initial 4 months after the accident, estimated by superimposing individual behaviour data on to a daily dose rate map, was less than 3 mSv in 93.9% of residents (maximum 15 mSv) in evacuation areas. Actual individual thyroid equivalent doses were less than 15 mSv in 98.8% of children (maximum 25 mSv) in evacuation areas. When uncertainty exists in dose estimation models, it may be sensible to err on the side of caution, and final estimated doses are often much greater than actual radiation doses. However, overestimation of the dose at the time of an accident has a great influence on the psychology of residents. More than 100 000 residents have not returned to the evacuation areas 5 years after the Fukushima accident because of the social and mental effects during the initial period of the disaster. Estimates of

  7. Evaluation of iodide deficiency in the lactating rat and pup using a biologically based dose response (BBDR) Model***

    Science.gov (United States)

    A biologically-based dose response (BBDR) model for the hypothalamic-pituitary thyroid (HPT) axis in the lactating rat and nursing pup was developed to describe the perturbations caused by iodide deficiency on the 1-IPT axis. Model calibrations, carried out by adjusting key model...

  8. Evaluation of iodide deficiency in the lactating rat and pup using a biologically based dose-response model

    Science.gov (United States)

    A biologically-based dose response (BBDR) model for the hypothalamic-pituitary thyroid (BPT) axis in the lactating rat and nursing pup was developed to describe the perturbations caused by iodide deficiency on the HPT axis. Model calibrations, carried out by adjusting key model p...

  9. Biological effects of ivermectin on the fowl tick Argas (Persicargas persicus (Oken (Ixodoidea: Argasidae

    Directory of Open Access Journals (Sweden)

    Marzouk, A.S.*; Swelim, H.H.*; Montasser, A.A.*and Gadallah, A.I.**

    2004-12-01

    Full Text Available The present study is carried out to assess the effect induced by different single subcutaneous injections of ivermectin (IVM (100, 200, 400, 800 or 1600 g/kg pigeon weight injected 2 or 7 days before tick feeding on some biological parameters such as mobility and viability, sexual activity, ingested blood, amount of coxal fluid, blood digestion and fertility in the tick Argas (P. persicus to define the effective dose. This effective dose was used in similar assessment conducted 2 or 3 weeks post injection in order to confirm the degradation of ivermectin concentration in the host blood and to determine the number of required doses for complete control . From this study we conclude: 1 IVM induces complete immobilization of both males and females when they are fed on hosts injected by doses over 100 g/kg. 2 The use of two doses of 400 g/kg with a week interval completely controls the tick population. 3 Sexual response was completely negative at doses over 200 g/kg. 4 The amount of coxal fluid emitted by both sexes decreased markedly when fed after host injection with all doses, whereas the amount of ingested blood remained generally not highly affected. 5 The number of ovipositing females, number of eggs deposited and their hatching percent decreased markedly with the increase of dose used. Blood digestion was not noticed in males at doses >200 ug/kg and in females at doses >100ug/kg .

  10. Biological Effects of Yeast β-Glucans

    Directory of Open Access Journals (Sweden)

    Vlatka Petravić-tominac

    2010-12-01

    Full Text Available β-Glucans are glucose polymers that naturally occur in yeasts, molds, algae, mushrooms, bacteria, oats and barley. Immunostimulation is one of the most important properties of β-glucans. They are classified as biological response modifiers and because of their biological activities they can be used in human and veterinary medicine and pharmacy. Additionally, β-glucans show interesting physicochemical properties and therefore could be applied in food and feed production as well as in cosmetic and chemical industries. Immunomodulation by β-glucan, both in vitro and in vivo, inhibits cancer cell growth and metastasis and prevents or reduces bacterial infection. In humans, dietary β-glucan lowers blood cholesterol, improves glucose utilization by body cells and also helps wound healing. β-Glucans work, in part, by stimulating the innate immune mechanism to fight a range of foreign challenges and could be used as an adjuvant, in combination with anti infective or antineoplastic agents, radiotherapy, and a range of topical agents and nutrients. The structure of β-glucans depends on the source they are isolated from. Native β-glucan molecules can be linked and branched in several ways. Biological properties of different β-glucan molecules are dependent on their molecular structure. Some authors claim that the β-(1→3, (1→6-glucan derived from yeast Saccharomyces cerevisiae produce the highest biological effects. Thus, in this review the β-glucans and their metabolic activity are discussed, with the special accent on those isolated from yeast. Other possible β-glucan applications, directed to cosmetic production, non-medical application in pharmaceutical and chemical industry, are also discussed.

  11. High-dose-rate brachytherapy in the treatment of uterine cervix cancer. Analysis of dose effectiveness and late complications

    International Nuclear Information System (INIS)

    Purpose: This retrospective analysis aims to report results of patients with cervix cancer treated by external beam radiotherapy (EBR) and high-dose-rate (HDR) brachytherapy. Methods and Materials: From September 1992 to December 1996, 138 patients with FIGO Stages II and III and mean age of 56 years were treated. Median EBR to the whole pelvis was 45 Gy in 25 fractions. Parametrial boost was performed in 93% of patients, with a median dose of 14.4 Gy. Brachytherapy with HDR was performed during EBR or following its completion with a dose of 24 Gy in four weekly fractions of 6 Gy to point A. Median overall treatment time was of 60 days. Patient age, tumor stage, and overall treatment time were variables analyzed for survival and local control. Cumulative biologic effective dose (BED) at rectal and bladder reference points were correlated with late complications in these organs and dose of EBR at parametrium was correlated with small bowel complications. Results: Median follow-up time was 38 months. Overall survival, disease-free survival, and local control at 5 years was 53.7%, 52.7%, and 62%, respectively. By multivariate and univariate analysis, overall treatment time up to 50 days was the only statistically significant adverse variable for overall survival (p=0.003) and actuarial local control (p=0.008). The 5-year actuarial incidence of rectal, bladder, and small bowel late complications was 16%, 11%, and 14%, respectively. Patients treated with cumulative BED at rectum points above 110 Gy3 and at bladder point above 125 Gy3 had a higher but not statistically significant 5-year actuarial rate of complications at these organs (18% vs. 12%, p=0.49 and 17% vs. 9%, p=0.20, respectively). Patients who received parametrial doses larger than 59 Gy had a higher 5-year actuarial rate of complications in the small bowel; however, this was not statistically significant (19% vs. 10%, p=0.260). Conclusion: This series suggests that 45 Gy to the whole pelvis combined with

  12. Biological effects of turf bamboo by 137Cs γ-rays irradiation

    International Nuclear Information System (INIS)

    137Cs γ-rays was used to treat bamboo rhizome or culture of turf bamboo, and to evaluate the biological was studied. It showed that low dose of irradiation had no effect on bud germination, high dose of irradiation delayed the bud germination. Sasa pygmaea was more resistant to γ-rays irradiation, and the lethal dose of Sasa culture was 20 ∼ 30 Gy. For Sasa fortunei culture the lethal dose was less than 20 Gy; and the lethal dose of bamboo rhizome for Indocalamus latifolius was 10 ∼ 20 Gy, for other 3 species of bamboo, the lethal dose was more than 80 Gy. The morphological feature of Sasa pygmaea, or Indocalamus latifolius, or Indocalamus decorous after irradiation was not obvious, but the white strip in its green leaves of Shibataea chinensis irradiated with 5 and 10 Gy was observed. (authors)

  13. Experimental dose effects after interstitial irradiation of the brain

    International Nuclear Information System (INIS)

    Experiments performed on healthy brain (beagle) were performed to study the dose effects of the gamma emitters iodine-125, iridium-192, and gold-198. Permanent implants with low dose rates were contrasted with temporary implants with high-dose rates at an identical accumulative total dose across the study period (5-365 days). The three radioisotopes used allow to achieve sharply demonstrated necrotic volumes in the healthy tissue. Necrotic volume and side effects in terms of a vasogenic oedema can be influenced in dependence from the emitter applied. Dose absorption is nonlinear in the case of permanent implants due to perifocal mineralization. In cases of high-dose-rate implants, nonlinear dose absorption is of secondary importance. Opening of the blood-brain barrier resulting in a vasogenic oedema is the limiting factor for the tolerance of the healthy brain. Application of temporary high-dose-rate iodine-125 seeds is already one conclusion drawn from these experimental findings which is relevant to clinical application for the treatment of human brain tumours. (orig./MG)

  14. Correlation between effective dose and radiological risk: general concepts*

    Science.gov (United States)

    Costa, Paulo Roberto; Yoshimura, Elisabeth Mateus; Nersissian, Denise Yanikian; Melo, Camila Souza

    2016-01-01

    The present review aims to offer an educational approach related to the limitations in the use of the effective dose mgnitude as a tool for the quantification of doses resulting from diagnostic applications of ionizing radiation. We present a critical analysis of the quantities accepted and currently used for dosimetric evaluation in diagnostic imaging procedures, based on studies published in the literature. It is highlighted the use of these quantities to evaluate the risk attributed to the procedure and to calculate the effective dose, as well as to determine its correct use and interpretation.

  15. Effects of Pesticides on Biological Systems

    Directory of Open Access Journals (Sweden)

    Ergul Belge Kurutas

    2003-06-01

    Full Text Available The use of pesticid both in Turkey and other contries is widespread in order to combat against many pests which cause economical damages. However, pesticides in human pass through skin, respiratory or digestive systems and is metabolized by monooxygenase system dependent upon cytocrome P450 in liver. They also give rise to severe decreases cytochrome P450 and amount of "hem" enzyme activites of glucose-6-phosphatase, pyrophosphatase by stimulating lipid peroxidation on hepatic microsomes. In this study effects of pesticides on biological systems will be presented in genaral terms. [Archives Medical Review Journal 2003; 12(3.000: 215-228

  16. Biological effects of synchrotron radiation on crops

    Institute of Scientific and Technical Information of China (English)

    唐掌雄; 董保中; 等

    1996-01-01

    The sensitivity of germinating seeds of barley,winter wheat and spring one to synchrotron ultraviolet radiation is barley>winter wheat and spring one.But when dry seeds of the three crops are irradiated by 3.5-22keV X-rays,the sequence of their sensitivity to radiation can be changed.for irradiation of 0.6-3keV ultra soft X-rays,0.40-0.90 of the seedlings of the first generation appear mutation of striped chlorophyll defect.This biological effect has never been found for irradiation of other rays.

  17. Biological effects data: Fluoride and sulfur dioxide

    Energy Technology Data Exchange (ETDEWEB)

    McMechan, K.J. (ed.); Holton, R.L.; Ulbricht, R.J.; Morgan , J.B.

    1975-04-01

    The Alumax Pacific Aluminum Corporation has proposed construction of an aluminum reduction facility near Youngs Bay at Warrenton, Oregon. This report comprises one part of the final report to Alumax on a research project entitled, Physical, Chemical and Biological Studies of Youngs Bay.'' It presents data pertaining to the potential biological effects of fluoride and sulfur dioxide, two potentially hazardous plant-stack emissions, on selected aquatic species of the area. Companion volumes provide a description of the physical characteristics the geochemistry, and the aquatic animals present in Youngs Bay and adjacent ecosystems. An introductory volume provides general information and maps of the area, and summarizes the conclusions of all four studies. The data from the two phases of the experimental program are included in this report: lethal studies on the effects of selected levels of fluoride and sulfur dioxide on the survival rate of eleven Youngs Bay faunal species from four phyla, and sublethal studies on the effects of fluoride and sulfur dioxide on the rate of primary production of phytoplankton. 44 refs., 18 figs., 38 tabs.

  18. Mass effect of injected dose in small rodent imaging by SPECT and PET

    Energy Technology Data Exchange (ETDEWEB)

    Kung, M.-P. [Department of Radiology, University of Pennsylvania, Philadelphia, PA 19104 (United States); Kung, Hank F. [Department of Radiology, University of Pennsylvania, Philadelphia, PA 19104 (United States) and Department of Pharmacology, University of Pennsylvania, Philadelphia, PA 19104 (United States)]. E-mail: kunghf@sunmac.spect.upenn.edu

    2005-10-01

    This paper discusses the effect of mass (chemical quantity) of injected dose on positron emission tomography (PET) and single-photon emission computed tomography (SPECT). Commonly, PET or SPECT imaging study uses a 'no-carrier added' dose, which contains a small amount of radioactive imaging agent (in picogram to microgram). For small animal (rodent) imaging studies, specifically targeting binding sites or biological processes, the mass (chemical quantity) in the dose may significantly modify the binding, pharmacokinetics and, ultimately, the imaging outcome. Due to differences in size and other physiological factors between humans and rodents, there is a dramatic divergence of mass effect between small animal and human imaging study. In small animal imaging studies, the mass, or effective dose (ED{sub 50}), a dose required for 50% of receptor or binding site occupancy, is usually not directly related to binding potential (B {sub max}/K {sub d}) (measured by in vitro binding assay). It is likely that dynamic interplays between specific and nonspecific binding in blood circulation, transient lung retention, kidney excretion, liver-gallbladder flow, soft tissue retention as well as metabolism could each play a significant role in determining the concentration of the tracer in the target regions. When using small animal imaging for studying drug occupancy (either by a pretreatment, coinjection or chasing dose), the mass effects on imaging outcome are important factors for consideration.

  19. Mass effect of injected dose in small rodent imaging by SPECT and PET

    International Nuclear Information System (INIS)

    This paper discusses the effect of mass (chemical quantity) of injected dose on positron emission tomography (PET) and single-photon emission computed tomography (SPECT). Commonly, PET or SPECT imaging study uses a 'no-carrier added' dose, which contains a small amount of radioactive imaging agent (in picogram to microgram). For small animal (rodent) imaging studies, specifically targeting binding sites or biological processes, the mass (chemical quantity) in the dose may significantly modify the binding, pharmacokinetics and, ultimately, the imaging outcome. Due to differences in size and other physiological factors between humans and rodents, there is a dramatic divergence of mass effect between small animal and human imaging study. In small animal imaging studies, the mass, or effective dose (ED50), a dose required for 50% of receptor or binding site occupancy, is usually not directly related to binding potential (B max/K d) (measured by in vitro binding assay). It is likely that dynamic interplays between specific and nonspecific binding in blood circulation, transient lung retention, kidney excretion, liver-gallbladder flow, soft tissue retention as well as metabolism could each play a significant role in determining the concentration of the tracer in the target regions. When using small animal imaging for studying drug occupancy (either by a pretreatment, coinjection or chasing dose), the mass effects on imaging outcome are important factors for consideration

  20. The effect of repeated exposures to low doses of ionizing radiation on the liver functions in the rat

    International Nuclear Information System (INIS)

    Radiation exposure is known to induce progressive biological effects on different cells, tissues and organs which may be more or less profound, depending on the radiosensitivity of the system, the dose level, rate and frequency of exposure. However, information is available on the biological effects of single and relatively high doses of radiation . In contrast, very little information is available on such effects after the exposure to small doses of radiation either delivered as single or repeated doses. The present study was planned to investigate the effects of repeated exposure to ionizing radiation (γ- rays) on some physiological and biochemical parameters of the liver function. A total number of 336 male albino rats (100-150 gm b.wt.) were used in four experiments which were designed to serve the objectives of this investigation

  1. Effective dose range for dental cone beam computed tomography scanners

    International Nuclear Information System (INIS)

    Objective: To estimate the absorbed organ dose and effective dose for a wide range of cone beam computed tomography scanners, using different exposure protocols and geometries. Materials and methods: Two Alderson Radiation Therapy anthropomorphic phantoms were loaded with LiF detectors (TLD-100 and TLD-100H) which were evenly distributed throughout the head and neck, covering all radiosensitive organs. Measurements were performed on 14 CBCT devices: 3D Accuitomo 170, Galileos Comfort, i-CAT Next Generation, Iluma Elite, Kodak 9000 3D, Kodak 9500, NewTom VG, NewTom VGi, Pax-Uni3D, Picasso Trio, ProMax 3D, Scanora 3D, SkyView, Veraviewepocs 3D. Effective dose was calculated using the ICRP 103 (2007) tissue weighting factors. Results: Effective dose ranged between 19 and 368 μSv. The largest contributions to the effective dose were from the remainder tissues (37%), salivary glands (24%), and thyroid gland (21%). For all organs, there was a wide range of measured values apparent, due to differences in exposure factors, diameter and height of the primary beam, and positioning of the beam relative to the radiosensitive organs. Conclusions: The effective dose for different CBCT devices showed a 20-fold range. The results show that a distinction is needed between small-, medium-, and large-field CBCT scanners and protocols, as they are applied to different indication groups, the dose received being strongly related to field size. Furthermore, the dose should always be considered relative to technical and diagnostic image quality, seeing that image quality requirements also differ for patient groups. The results from the current study indicate that the optimisation of dose should be performed by an appropriate selection of exposure parameters and field size, depending on the diagnostic requirements.

  2. Carbon Heavy-ion Radiation Induced Biological effects on Oryza sativa L.

    Science.gov (United States)

    Zhang, Meng; Sun, Yeqing; Li, Xishan; Gong, Ning; Meng, Qingmei; Liu, Jiawei; Wang, Ting

    2016-07-01

    Large number of researches on rice after spaceflights indicated that rice was a favorable model organism to study biological effects induced by space radiation. The stimulative effect could often be found on rice seedlings after irradiation by low-dose energetic heavy-ion radiation. Spaceflight also could induce stimulative effect on kinds of seeds. To further understand the mechanism of low-dose radiation biological effects and the dose range, the germinated rice seeds which were irradiated by different doses of carbon heavy-ion (0, 0.02, 0.1, 0.2, 1, 2, 5, 10, 15 and 20Gy, LET=27.3keV/µm) were used as materials to study. By investigating the variation of rice phenotype under different doses, we found that 2Gy radiation dose was a dividing point of the phenotypic variation. Transmission electron microscopy was used to observe the variation of mitochondria, chloroplast, endoplasmic reticulum, ribosome and nucleus in mesophyll cell of rice apical meristem at 24 hours after radiation with different doses. The cells were not apparently physiologically damaged when the dose of radiation was less than 2Gy. The number of chloroplast did not change significantly, but the number of mitochondria was significantly increased, and gathered around in the chloroplast and endoplasmic reticulum; the obvious lesion of chloroplast and mitochondria were found at the mesophyll cells when radiation dose was higher than 2Gy. The mitochondria were swelling and appearing blurred crest. The chloroplast and mitochondrial mutation rate increased significantly (pplant. Keywords: Heavy-ion radiation; Low dose; Stimulation effect; Inhibition effect; Rice.

  3. Relative Biological Effectiveness of HZE Particles for Chromosomal Exchanges and Other Surrogate Cancer Risk Endpoints.

    Science.gov (United States)

    Cacao, Eliedonna; Hada, Megumi; Saganti, Premkumar B; George, Kerry A; Cucinotta, Francis A

    2016-01-01

    The biological effects of high charge and energy (HZE) particle exposures are of interest in space radiation protection of astronauts and cosmonauts, and estimating secondary cancer risks for patients undergoing Hadron therapy for primary cancers. The large number of particles types and energies that makeup primary or secondary radiation in HZE particle exposures precludes tumor induction studies in animal models for all but a few particle types and energies, thus leading to the use of surrogate endpoints to investigate the details of the radiation quality dependence of relative biological effectiveness (RBE) factors. In this report we make detailed RBE predictions of the charge number and energy dependence of RBE's using a parametric track structure model to represent experimental results for the low dose response for chromosomal exchanges in normal human lymphocyte and fibroblast cells with comparison to published data for neoplastic transformation and gene mutation. RBE's are evaluated against acute doses of γ-rays for doses near 1 Gy. Models that assume linear or non-targeted effects at low dose are considered. Modest values of RBE (10) are predicted at low doses <0.1 Gy. The radiation quality dependence of RBE's against the effects of acute doses γ-rays found for neoplastic transformation and gene mutation studies are similar to those found for simple exchanges if a linear response is assumed at low HZE particle doses. Comparisons of the resulting model parameters to those used in the NASA radiation quality factor function are discussed. PMID:27111667

  4. Relative Biological Effectiveness of HZE Particles for Chromosomal Exchanges and Other Surrogate Cancer Risk Endpoints

    Science.gov (United States)

    Cacao, Eliedonna; Hada, Megumi; Saganti, Premkumar B.; George, Kerry A.; Cucinotta, Francis A.

    2016-01-01

    The biological effects of high charge and energy (HZE) particle exposures are of interest in space radiation protection of astronauts and cosmonauts, and estimating secondary cancer risks for patients undergoing Hadron therapy for primary cancers. The large number of particles types and energies that makeup primary or secondary radiation in HZE particle exposures precludes tumor induction studies in animal models for all but a few particle types and energies, thus leading to the use of surrogate endpoints to investigate the details of the radiation quality dependence of relative biological effectiveness (RBE) factors. In this report we make detailed RBE predictions of the charge number and energy dependence of RBE’s using a parametric track structure model to represent experimental results for the low dose response for chromosomal exchanges in normal human lymphocyte and fibroblast cells with comparison to published data for neoplastic transformation and gene mutation. RBE’s are evaluated against acute doses of γ-rays for doses near 1 Gy. Models that assume linear or non-targeted effects at low dose are considered. Modest values of RBE (10) are predicted at low doses <0.1 Gy. The radiation quality dependence of RBE’s against the effects of acute doses γ-rays found for neoplastic transformation and gene mutation studies are similar to those found for simple exchanges if a linear response is assumed at low HZE particle doses. Comparisons of the resulting model parameters to those used in the NASA radiation quality factor function are discussed. PMID:27111667

  5. Relative Biological Effectiveness of HZE Particles for Chromosomal Exchanges and Other Surrogate Cancer Risk Endpoints.

    Directory of Open Access Journals (Sweden)

    Eliedonna Cacao

    Full Text Available The biological effects of high charge and energy (HZE particle exposures are of interest in space radiation protection of astronauts and cosmonauts, and estimating secondary cancer risks for patients undergoing Hadron therapy for primary cancers. The large number of particles types and energies that makeup primary or secondary radiation in HZE particle exposures precludes tumor induction studies in animal models for all but a few particle types and energies, thus leading to the use of surrogate endpoints to investigate the details of the radiation quality dependence of relative biological effectiveness (RBE factors. In this report we make detailed RBE predictions of the charge number and energy dependence of RBE's using a parametric track structure model to represent experimental results for the low dose response for chromosomal exchanges in normal human lymphocyte and fibroblast cells with comparison to published data for neoplastic transformation and gene mutation. RBE's are evaluated against acute doses of γ-rays for doses near 1 Gy. Models that assume linear or non-targeted effects at low dose are considered. Modest values of RBE (10 are predicted at low doses <0.1 Gy. The radiation quality dependence of RBE's against the effects of acute doses γ-rays found for neoplastic transformation and gene mutation studies are similar to those found for simple exchanges if a linear response is assumed at low HZE particle doses. Comparisons of the resulting model parameters to those used in the NASA radiation quality factor function are discussed.

  6. Behaviour of polymers in radioactive environments: Effects of dose speed

    International Nuclear Information System (INIS)

    The scope of this research is to determine the degradation of mechanical properties of cable insulating PVC after irradiation in air at a Cobalt-60 (γ-ray) facility. Amongst the mechanical properties elongation at break and tensile strength were chosen as they are the most sensible to radiation. The samples were exposed to combined radiation-thermal environments with constant airflow in order to obtain accelerated aging data a doses up to 50-300 kGy, with dose rates ranging between 1.3 and 5.6 kGy/h at temperatures from 60 degrees C to 100 degrees C. At lower dose rates the degradation of mechanical properties increased after the same total dose: elongation at break decreases sharply while tensile strength decreases to a less extent, showing dose rate effects. A strong synergy between irradiation and thermal processes was also observed. (author)

  7. Ionizing radiation effects on biological macromolecules

    International Nuclear Information System (INIS)

    Ionizing radiation is one of the main environmental factors for life, particularly for human beings. The primary effects of ionizing radiation produce the perturbation of biomacromolecules functionality (DNA and proteins). This effect occurs by direct action and by the indirect way of water molecules radiolysis. These primary effects result in a cascade of biochemical and biological consequences that may finally influence the general functions of the organism. In the last five decades the research activity in this field was focused on the detailed description of the effects on DNA molecules and their biochemical and biological consequences. The reason for this is the importance of the integrity of DNA for the cell life evolution, especially for the cell recovery processes or for the programmed cell death after irradiation. These aspects have main applications in very important fields as radioprotection and radiotherapy. In the present paper the mechanisms of ionizing radiation action at the molecular level will be reviewed, with focus on the protein level effects. Although comparatively a lower number of results was reported concerning the effects of ionizing radiation on the proteins, during the last years this field was reconsidered in the context of a new research trend in the field of genomics and proteomics. The structural changes which occur most often in the proteins are the breaks of chemical links, the chemical moieties ionization (for instance, the oxidation of the proteins) and the inter - protein new links (cross-linking). These changes result in a gradual loss of protein functionality, influencing particularly the ionic transport, the signal transduction across the membrane or intermolecular recognition processes of antibody-antigen type. Some studies on the ion artificial channels (as gramicidin and amphotericin) incorporated in model membranes (BLM-s or liposomes) describe structural and functional changes of the peptides after the exposure to

  8. Effect of staff training on radiation dose in pediatric CT

    Energy Technology Data Exchange (ETDEWEB)

    Hojreh, Azadeh, E-mail: azadeh.hojreh@meduniwien.ac.at [Medical University of Vienna, Department of Biological Imaging and Image-guided Therapy, Division of General and Paediatric Radiology, Waehringer Guertel 18–20, A-1090 Vienna (Austria); Weber, Michael, E-mail: michael.Weber@Meduniwien.Ac.At [Medical University of Vienna, Department of Biomedical Imaging and Image-guided Therapy, Division of General and Paediatric Radiology, Waehringer Guertel 18–20, A-1090 Vienna (Austria); Homolka, Peter, E-mail: peter.Homolka@Meduniwien.Ac.At [Medical University of Vienna, Centre for Medical Physics and Biomedical Engineering, Waehringer Guertel 18–20, A-1090 Vienna (Austria)

    2015-08-15

    Highlights: • Pediatric patient CT doses were compared before and after staff training. • Staff training increasing dose awareness resulted in patient dose reduction. • Application of DRL reduced number of CT's with unusually high doses. • Continuous education and training are effective regarding dose optimization. - Abstract: Objective: To evaluate the efficacy of staff training on radiation doses applied in pediatric CT scans. Methods: Pediatric patient doses from five CT scanners before (1426 scans) and after staff training (2566 scans) were compared statistically. Examinations included cranial CT (CCT), thoracic, abdomen–pelvis, and trunk scans. Dose length products (DLPs) per series were extracted from CT dose reports archived in the PACS. Results: A pooled analysis of non-traumatic scans revealed a statistically significant reduction in the dose for cranial, thoracic, and abdomen/pelvis scans (p < 0.01). This trend could be demonstrated also for trunk scans, however, significance could not be established due to low patient frequencies (p > 0.05). The percentage of scans performed with DLPs exceeding the German DRLs was reduced from 41% to 7% (CCT), 19% to 5% (thorax-CT), from 9% to zero (abdominal–pelvis CT), and 26% to zero (trunk; DRL taken as summed DRLs for thorax plus abdomen–pelvis, reduced by 20% accounting for overlap). Comparison with Austrian DRLs – available only for CCT and thorax CT – showed a reduction from 21% to 3% (CCT), and 15 to 2% (thorax CT). Conclusions: Staff training together with application of DRLs provide an efficient approach for optimizing radiation dose in pediatric CT practice.

  9. Effect of staff training on radiation dose in pediatric CT

    International Nuclear Information System (INIS)

    Highlights: • Pediatric patient CT doses were compared before and after staff training. • Staff training increasing dose awareness resulted in patient dose reduction. • Application of DRL reduced number of CT's with unusually high doses. • Continuous education and training are effective regarding dose optimization. - Abstract: Objective: To evaluate the efficacy of staff training on radiation doses applied in pediatric CT scans. Methods: Pediatric patient doses from five CT scanners before (1426 scans) and after staff training (2566 scans) were compared statistically. Examinations included cranial CT (CCT), thoracic, abdomen–pelvis, and trunk scans. Dose length products (DLPs) per series were extracted from CT dose reports archived in the PACS. Results: A pooled analysis of non-traumatic scans revealed a statistically significant reduction in the dose for cranial, thoracic, and abdomen/pelvis scans (p < 0.01). This trend could be demonstrated also for trunk scans, however, significance could not be established due to low patient frequencies (p > 0.05). The percentage of scans performed with DLPs exceeding the German DRLs was reduced from 41% to 7% (CCT), 19% to 5% (thorax-CT), from 9% to zero (abdominal–pelvis CT), and 26% to zero (trunk; DRL taken as summed DRLs for thorax plus abdomen–pelvis, reduced by 20% accounting for overlap). Comparison with Austrian DRLs – available only for CCT and thorax CT – showed a reduction from 21% to 3% (CCT), and 15 to 2% (thorax CT). Conclusions: Staff training together with application of DRLs provide an efficient approach for optimizing radiation dose in pediatric CT practice

  10. Choline PET based dose-painting in prostate cancer - Modelling of dose effects

    Science.gov (United States)

    2010-01-01

    Background Several randomized trials have documented the value of radiation dose escalation in patients with prostate cancer, especially in patients with intermediate risk profile. Up to now dose escalation is usually applied to the whole prostate. IMRT and related techniques currently allow for dose escalation in sub-volumes of the organ. However, the sensitivity of the imaging modality and the fact that small islands of cancer are often dispersed within the whole organ may limit these approaches with regard to a clear clinical benefit. In order to assess potential effects of a dose escalation in certain sub-volumes based on choline PET imaging a mathematical dose-response model was developed. Methods Based on different assumptions for α/β, γ50, sensitivity and specificity of choline PET, the influence of the whole prostate and simultaneous integrated boost (SIB) dose on tumor control probability (TCP) was calculated. Based on the given heterogeneity of all potential variables certain representative permutations of the parameters were chosen and, subsequently, the influence on TCP was assessed. Results Using schedules with 74 Gy within the whole prostate and a SIB dose of 90 Gy the TCP increase ranged from 23.1% (high detection rate of choline PET, low whole prostate dose, high γ50/ASTRO definition for tumor control) to 1.4% TCP gain (low sensitivity of PET, high whole prostate dose, CN + 2 definition for tumor control) or even 0% in selected cases. The corresponding initial TCP values without integrated boost ranged from 67.3% to 100%. According to a large data set of intermediate-risk prostate cancer patients the resulting TCP gains ranged from 22.2% to 10.1% (ASTRO definition) or from 13.2% to 6.0% (CN + 2 definition). Discussion Although a simplified mathematical model was employed, the presented model allows for an estimation in how far given schedules are relevant for clinical practice. However, the benefit of a SIB based on choline PET seems less than

  11. Choline PET based dose-painting in prostate cancer - Modelling of dose effects

    International Nuclear Information System (INIS)

    Several randomized trials have documented the value of radiation dose escalation in patients with prostate cancer, especially in patients with intermediate risk profile. Up to now dose escalation is usually applied to the whole prostate. IMRT and related techniques currently allow for dose escalation in sub-volumes of the organ. However, the sensitivity of the imaging modality and the fact that small islands of cancer are often dispersed within the whole organ may limit these approaches with regard to a clear clinical benefit. In order to assess potential effects of a dose escalation in certain sub-volumes based on choline PET imaging a mathematical dose-response model was developed. Based on different assumptions for α/β, γ50, sensitivity and specificity of choline PET, the influence of the whole prostate and simultaneous integrated boost (SIB) dose on tumor control probability (TCP) was calculated. Based on the given heterogeneity of all potential variables certain representative permutations of the parameters were chosen and, subsequently, the influence on TCP was assessed. Using schedules with 74 Gy within the whole prostate and a SIB dose of 90 Gy the TCP increase ranged from 23.1% (high detection rate of choline PET, low whole prostate dose, high γ50/ASTRO definition for tumor control) to 1.4% TCP gain (low sensitivity of PET, high whole prostate dose, CN + 2 definition for tumor control) or even 0% in selected cases. The corresponding initial TCP values without integrated boost ranged from 67.3% to 100%. According to a large data set of intermediate-risk prostate cancer patients the resulting TCP gains ranged from 22.2% to 10.1% (ASTRO definition) or from 13.2% to 6.0% (CN + 2 definition). Although a simplified mathematical model was employed, the presented model allows for an estimation in how far given schedules are relevant for clinical practice. However, the benefit of a SIB based on choline PET seems less than intuitively expected. Only under the

  12. Fundamental studies on the radiation chemical dose-response with use of thymine. Is activation of the surface between radiation biology and radiation chemistry possible?

    International Nuclear Information System (INIS)

    The review described the importance and difficulty of radiation chemical assessment of dose-response. The assessment has the tasks of the unit, low dose region evaluation and direct/indirect effects in biology. The authors' vacuum evaporated thymine for G-value determination is appropriate for XANES (X-ray absorption near edge structures) measurement with monochromic ultrasoft X-rays (-550 eV photon) generated by SPring-8. However, the data of yielded thymine derivatives as well as those yielded after 60Co γ-ray (1.5 MeV photon) irradiation are not suitable for direct application in DNA damage evaluation of living cells due to trans-scientific uncertainty. Efforts are required for reducing the uncertainty present in dose-response assessment. (K.H.)

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

    International Nuclear Information System (INIS)

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

  14. EFFECTS OF FOCUS FILM DISTANCE (FFD) VARIATION ON ENTRANCE TESTICULAR DOSE IN LUMBAR-PELVIC RADIOGRAPHY

    OpenAIRE

    Dilger, Ron; Egan, Ingrid; Hayek, Ray

    1997-01-01

    Introduction: With the steady increase in public and professional concern regarding the biological effects of ionising radiation, there is a need for both the Chiropractic and Radiography professions to improve imaging techniques for the lowering of patient radiation doses. Lumbar radiographs are essential in chiropractic general practice for biomechanical diagnosis and postural analysis. Detailed anatomical measurements are taken from spinal radiographs for the determination of various biome...

  15. The biological effects of ozone depletion.

    Science.gov (United States)

    Young, A R

    1997-05-01

    Thinning of the ozone layer is predicted to result in increased levels of ultraviolet (UV) B radiation at the earth's surface. This effect has been confirmed by measurements made in relatively unpolluted areas such as Antarctica, the southern part of South America and at mid-to-high latitudes in the northern hemisphere. It has been harder to show in populated northern latitudes because of a number of confounding factors, notably weather systems and low level ozone pollution. Although UVB forms only a small proportion of the UV spectrum it has potent biological effects so that a small increase in penetration of UVB to the earth's surface has profound effects on a wide range of life forms. Most attention has been paid to the effects of an increase in UVB on human health, particularly the effects on skin cancer, resistance to infectious diseases and cataract formation. However, the effects of increased levels of UVB on other parts of the ecosystem, particularly on the primary producers in aquatic and terrestrial food chains, may be of even. PMID:9519507

  16. Calculation of patient effective dose and scattered dose for dental mobile fluoroscopic equipment: Application of the Monte Carlo simulation

    International Nuclear Information System (INIS)

    The objective of this study was to evaluate the patient effective dose and scattered dose from recently developed dental mobile equipment in Korea. The MCNPX 2.6 (Los Alamos National Laboratory, USA) was used in a Monte Carlo simulation to calculate both the effective and scattered doses. The MCNPX code was constructed identically as in the general use of equipment and the effective dose and scattered dose were calculated using the KTMAN-2 digital phantom. The effective dose was calculated as 906 μSv. The equivalent doses per organ were calculated via the MCNPX code, and were 32 174 and 19 μSv in the salivary gland and oesophagus, respectively. The scattered dose of 22.5-32.6 μSv of the tube side at 25 cm from the centre in anterior and posterior planes was measured as 1.4-3 times higher than the detector side of 10.5-16.0 μSv. (authors)

  17. Comparing Effects of Biologic Agents in Treating Patients with Rheumatoid Arthritis: A Multiple Treatment Comparison Regression Analysis.

    Directory of Open Access Journals (Sweden)

    Ingunn Fride Tvete

    Full Text Available Rheumatoid arthritis patients have been treated with disease modifying anti-rheumatic drugs (DMARDs and the newer biologic drugs. We sought to compare and rank the biologics with respect to efficacy. We performed a literature search identifying 54 publications encompassing 9 biologics. We conducted a multiple treatment comparison regression analysis letting the number experiencing a 50% improvement on the ACR score be dependent upon dose level and disease duration for assessing the comparable relative effect between biologics and placebo or DMARD. The analysis embraced all treatment and comparator arms over all publications. Hence, all measured effects of any biologic agent contributed to the comparison of all biologic agents relative to each other either given alone or combined with DMARD. We found the drug effect to be dependent on dose level, but not on disease duration, and the impact of a high versus low dose level was the same for all drugs (higher doses indicated a higher frequency of ACR50 scores. The ranking of the drugs when given without DMARD was certolizumab (ranked highest, etanercept, tocilizumab/ abatacept and adalimumab. The ranking of the drugs when given with DMARD was certolizumab (ranked highest, tocilizumab, anakinra/rituximab, golimumab/ infliximab/ abatacept, adalimumab/ etanercept [corrected]. Still, all drugs were effective. All biologic agents were effective compared to placebo, with certolizumab the most effective and adalimumab (without DMARD treatment and adalimumab/ etanercept (combined with DMARD treatment the least effective. The drugs were in general more effective, except for etanercept, when given together with DMARDs.

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

    International Nuclear Information System (INIS)

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

  19. Effect of radon measurement methods on dose estimation

    International Nuclear Information System (INIS)

    Different radon measurement methods were applied in the old and new buildings of the Turkish bath of Eger (Hungary), in order to elaborate a radon measurement protocol. Besides, measurements were also made concerning the radon and thoron short-lived decay products, gamma dose from external sources and water radon. The most accurate results for dose estimation were provided by the application of personal radon meters. Estimated annual effective doses from radon and its short-lived decay products in the old and new buildings, using 0.2 and 0.1 measured equilibrium factors, were 0.83 and 0.17 mSv, respectively. The effective dose from thoron short-lived decay products was only 5 % of these values. The respective external gamma radiation effective doses were 0.19 and 0.12 mSvy-1. Effective dose from the consumption of tap water containing radon was 0.05 mSvy-1, while in the case of spring water, it was 0.14 mSvy-1. (authors)

  20. Effect of radon measurement methods on dose estimation.

    Science.gov (United States)

    Kávási, Norbert; Kobayashi, Yosuke; Kovács, Tibor; Somlai, János; Jobbágy, Viktor; Nagy, Katalin; Deák, Eszter; Berhés, István; Bender, Tamás; Ishikawa, Tetsuo; Tokonami, Shinji; Vaupotic, Janja; Yoshinaga, Shinji; Yonehara, Hidenori

    2011-05-01

    Different radon measurement methods were applied in the old and new buildings of the Turkish bath of Eger, Hungary, in order to elaborate a radon measurement protocol. Besides, measurements were also made concerning the radon and thoron short-lived decay products, gamma dose from external sources and water radon. The most accurate results for dose estimation were provided by the application of personal radon meters. Estimated annual effective doses from radon and its short-lived decay products in the old and new buildings, using 0.2 and 0.1 measured equilibrium factors, were 0.83 and 0.17 mSv, respectively. The effective dose from thoron short-lived decay products was only 5 % of these values. The respective external gamma radiation effective doses were 0.19 and 0.12 mSv y(-1). Effective dose from the consumption of tap water containing radon was 0.05 mSv y(-1), while in the case of spring water, it was 0.14 mSv y(-1). PMID:21450699

  1. The therapeutic effect of different dose 131I on hyperthyroidism

    International Nuclear Information System (INIS)

    1228 hyperthyroidism patients treated with two doses of 131I 3.7-4.4 MBq/g and 2.59-3.96 MBq/g are observed and the results are compared. The results indicate that the administered dose is larger the treating rate is higher, and hypothyroidation occurs frequently; while the dose is lower, the treating rate and hypothyroidation is also getting lower. So, there are some other factors of the indication selection, the estimation of thyroidism size, individual sensitively and the hyperthyroidism nature history and so on should be considered in the hyperthyroidism therapy for improving the therapeutic effect

  2. Low dose effects - is the fear more dangerous than the radiation?

    International Nuclear Information System (INIS)

    The use of hypothesis which assumes a dose / harmful effect relationship without a limit allows the calculation of risks attributable to doses too small to produce detectable, harmful biological effects. The daughter product of this hypothesis is ALARA concept which requires that the dose received is kept as low as reasonably achievable. This concept of prudent avoidance is generally accepted by international radiation protection organisations and universally applied by radiation health professionals. The acceptance of a hypothesis which assumes that a single nuclear event can cause carcinogenesis, has generated levels of anxiety which may have resulted in significant detriment to those possibly exposed to ionising radiation. The anxiety generated may have caused more detriment and a higher death rate than the worst case ' theoretical' value calculated using the Linear or Quadratic Linear Hypothesis. Information selected from reports and comments in relevant publications indicating that this possibility has become a realty is presented. 24 refs

  3. Health effects of daily airborne particle dose in children: Direct association between personal dose and respiratory health effects

    International Nuclear Information System (INIS)

    Air pollution is a widespread health problem associated with respiratory symptoms. Continuous exposure monitoring was performed to estimate alveolar and tracheobronchial dose, measured as deposited surface area, for 103 children and to evaluate the long-term effects of exposure to airborne particles through spirometry, skin prick tests and measurement of exhaled nitric oxide (eNO). The mean daily alveolar deposited surface area dose received by children was 1.35 × 103 mm2. The lowest and highest particle number concentrations were found during sleeping and eating time. A significant negative association was found between changes in pulmonary function tests and individual dose estimates. Significant differences were found for asthmatics, children with allergic rhinitis and sensitive to allergens compared to healthy subjects for eNO. Variation is a child's activity over time appeared to have a strong impact on respiratory outcomes, which indicates that personal monitoring is vital for assessing the expected health effects of exposure to particles. -- Highlights: •Particle dose was estimated through personal monitoring on more than 100 children. •We focused on real-time daily dose of particle alveolar deposited surface area. •Spirometry, skin prick and exhaled Nitric Oxide tests were performed. •Negative link was found between changes in pulmonary functions and individual doses. •A child's lifestyle appeared to have a strong impact on health respiratory outcomes. -- The respiratory health effects of daily airborne particle dose on children through personal monitoring

  4. Biological effect of radiation on human

    International Nuclear Information System (INIS)

    1. Adaptive response when 0.01 Gy was preirradiated before high challenging dose is induced in normal cell types such normal lymphocytes, primary keratinocytes, and L929 fibroblast cells but not in neoplastic cells such as L5178Y lymphoma cells, EL-4 lymphoma cells and 308 papilloma cells. 2. Heat shock protein (HSP) 25 and inducible HSP70 is responsible for the induction of adaptive response and radioresistance - cell cycle regulation, antiapoptotic molecule and PKC activation were involved. 3. Apoptosis was induced at most 5. hrs after irradiation in primary keratinocytes, in v-rasHa transformed keratinocytes, the maximum interval was 16 hrs, and in 308 papilloma cells, the maximum was 48 hrs. 4. PKC response by radiation is correlated with induction of apoptosis. 5. Rapid induction PKCdelta in primary keratinocytes and no response of PKC epsilon may involved in radiation induced apoptosis. 6. The rate of resorption was increased when radiation was given at 2.5 days after gestation. Early death including foetal death were highly expressed when radiation was given at 7.5 days after gestation. There are no difference in incidence of late death including embryonic death. 7. 2 Gy is the most effective dose in radiation induced teratogenesis in mouse model. 8. Growth retardation and small head was present when radiation was given at 5.5, 7.5, 11.5 and 15.5 days after gestation and small head showed high incidence at 11.5 days after gestation. 9. External malformation, internal malformation and skeletal malformation was induced when radiation was given at 7.5 days after gestation. 10. OGG1-mutated cells induced radiosensitive by G2/M cell cycle arrest. 11. Radiation induced G2/M phase cell cycle and correlated with radiosensitivity. 12. PKCalpha induced differentiation. 13. Radiation exposed cells showed carcinogenic effect. 14. Organ specific radiosensitivity was shown and protein expression was involved

  5. Biological effect of radiation on human

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Yun Sil; Cho, Chul Koo; Lee, Su Jae [and others

    2000-04-01

    1. Adaptive response when 0.01 Gy was preirradiated before high challenging dose is induced in normal cell types such normal lymphocytes, primary keratinocytes, and L929 fibroblast cells but not in neoplastic cells such as L5178Y lymphoma cells, EL-4 lymphoma cells and 308 papilloma cells. 2. Heat shock protein (HSP) 25 and inducible HSP70 is responsible for the induction of adaptive response and radioresistance - cell cycle regulation, antiapoptotic molecule and PKC activation were involved. 3. Apoptosis was induced at most 5. hrs after irradiation in primary keratinocytes, in v-rasHa transformed keratinocytes, the maximum interval was 16 hrs, and in 308 papilloma cells, the maximum was 48 hrs. 4. PKC response by radiation is correlated with induction of apoptosis. 5. Rapid induction PKCdelta in primary keratinocytes and no response of PKC epsilon may involved in radiation induced apoptosis. 6. The rate of resorption was increased when radiation was given at 2.5 days after gestation. Early death including foetal death were highly expressed when radiation was given at 7.5 days after gestation. There are no difference in incidence of late death including embryonic death. 7. 2 Gy is the most effective dose in radiation induced teratogenesis in mouse model. 8. Growth retardation and small head was present when radiation was given at 5.5, 7.5, 11.5 and 15.5 days after gestation and small head showed high incidence at 11.5 days after gestation. 9. External malformation, internal malformation and skeletal malformation was induced when radiation was given at 7.5 days after gestation. 10. OGG1-mutated cells induced radiosensitive by G2/M cell cycle arrest. 11. Radiation induced G2/M phase cell cycle and correlated with radiosensitivity. 12. PKCalpha induced differentiation. 13. Radiation exposed cells showed carcinogenic effect. 14. Organ specific radiosensitivity was shown and protein expression was involved.

  6. Biological Effects of Yeast β-Glucans

    Directory of Open Access Journals (Sweden)

    Vlatka Petravić-Tominac

    2014-02-01

    Full Text Available Normal 0 21 false false false MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-parent:""; mso-padding-alt:0pt 5.4pt 0pt 5.4pt; mso-para-margin:0pt; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman"; mso-ansi-language:#0400; mso-fareast-language:#0400; mso-bidi-language:#0400;} β-Glucans are glucose polymers that naturally occur in yeasts, molds, algae, mushrooms, bacteria, oats and barley. Immunostimulation is one of the most important properties of β-glucans. They are classified as biological response modifiers and because of their biological activities they can be used in human and veterinary medicine and pharmacy. Additionally, β-glucans show interesting physicochemical properties and therefore could be applied in food and feed production as well as in cosmetic and chemical industries. Immunomodulation by β-glucan, both in vitro and in vivo, inhibits cancer cell growth and metastasis and prevents or reduces bacterial infection. In humans, dietary β-glucan lowers blood cholesterol, improves glucose utilization by body cells and also helps wound healing. β-Glucans work, in part, by stimulating the innate immune mechanism to fight a range of foreign challenges and could be used as an adjuvant, in combination with anti infective or antineoplastic agents, radiotherapy, and a range of topical agents and nutrients. The structure of β-glucans depends on the source they are isolated from. Native β-glucan molecules can be linked and branched in several ways. Biological properties of different β-glucan molecules are dependent on their molecular structure. Some authors claim that the β-(1→3, (1→6-glucan derived from yeast Saccharomyces cerevisiae produce the highest biological effects. Thus, in this review the β-glucans and their metabolic

  7. Fluence-to-effective dose conversion coefficients for muons

    International Nuclear Information System (INIS)

    Fluence-to-effective dose conversion coefficients have been computed for negative and positive muons through Monte Carlo simulations with the FLUKA code. Calculations have been performed for various geometrical conditions of irradiation of an hermaphrodite phantom, placed in a vacuum. The energy range investigated was 1 MeV to 10 TeV. The calculated results are presented and discussed. A graphical presentation of organ doses is also given. (Author)

  8. Effects of sterilising doses of gamma radiation on drugs

    International Nuclear Information System (INIS)

    Effects of gamma radiation on drugs in solid state and aqueous solution were studied after application of doses of 2.5 and 5.0 Mrad (dose rate 0.1 Mrad/hour). Whereas solid substances only showed colour changes dissolved substances were decomposed to a somewhat higher degree than by heating in an autoclave at a temperature of 120 0C. (author)

  9. Dose effect of guidewire position in intravascular brachytherapy

    International Nuclear Information System (INIS)

    It has been reported that the dose effects of metallic guidewires are significant in intravascular brachytherapy (IVBT) using a beta source. The purpose of this work is to investigate the dependence of these dose effects on guidewire position. The EGS4 Monte Carlo codes were used to perform the dose calculations for the 90Sr (NOVOSTE), 32P (Guidant) and 192Ir (BEST Ind.) sources with and without a guidewire in place. Guidewires were placed at various distances from the central axes of the sources. Due to the attenuation by the guidewires, a dose reduction of up to 70% behind a guidewire was observed for the beta sources, while the dose perturbation was found to be negligible for the gamma source. The dose reduction for the beta sources was found to be dependent on the guidewire location. For example, the dose reduction was 10% higher for a stainless steel guidewire located at 0.5 mm than that for the guidewire at 2 mm from the central axis of the source. The portion of the target volume affected (shadowed) dosimetrically by the guidewire was reduced when the guidewire was positioned farther away from the source. The shadow volume (in which the dose reduction occurs) can be reduced by up to 45% as the guidewire is moved away from the source axis from 0.5 mm to 2 mm. The dosimetric perturbations due to the presence of a metallic guidewire as well as their dependence on guidewire location should be considered in designing a new IVBT delivery device, in analysing the treatment efficacy, and/or in dose prescription for a beta source. (author)

  10. Biological effect of carbon beams on cultured human cells

    International Nuclear Information System (INIS)

    This study was performed to determine the biological effect of carbon beams on 13 human tumor cells, in comparison with 200 KVp X-rays. Carbon beams were generated by the Riken Ring Cyclotron. The RBE (relative biological effectiveness) values were distributed from 1.46 to 2.20 for LET of 20 keV/μm, and 2.29-3.54 for 80 keV/μm. The RBEs were increased in all cell lines as the LET of carbon beams was increased from 20 to 80 keV/μm. There was no significant difference in radiosensitivity between cells from adenocarcinoma and those from squamous cell carcinoma. The relationship between the radiosensitivity of cells to X-rays and RBE was analyzed, but no significant correlation was suggested. Several survival curves of 20-40 keV/μm carbon beam irradiation showed the initial shoulders and the recovery ratios between two split doses were determined. Recovery was observed for LET of 2O keV/μm but not for that of 40 keV/μm. Furthermore, recovery ratios were 1.0-1.8, smaller than those for X-rays (1.5-2.4). (author)

  11. Correlation between γ-ray-induced DNA double-strand breakage and cell killing after biologically relevant doses: analysis by pulsed-field gel electrophoresis

    International Nuclear Information System (INIS)

    We examined the degree of correlation between γ-ray-induced lethality and DNA double-strand breaks (dsbs) after biologically relevant doses of radiation. Radiation lethality was modified by treating 14C-labelled Chinese hamster ovary cells with either of two aminothiols (WR-1065 or WR-255591) and the associated effect on dsb induction was determined by pulsed-field gel electrophoresis (PFGE). The use of phosphorimaging to analyse the distribution of 14C-activity in the gel greatly improved the low-dose resolution of the PFGE assay. Both WR-1065 and WR-255591 protected against dsb induction and lethality to a similar extent after low doses of radiation. although this correlation broke down when supralethal doses were used to induce dsbs. Thus, the level of dsbs induced in these cells as measured by PFGE after survival-curve doses of γ-radiation is consistently predictive of the degree of lethality obtained, implying a cause-effect relationship between these two parameters and confirming previous results obtained using the neutral filter elution assay for dsbs. (author)

  12. Analysis of dose in teeth for estimation of effective dose by the electron spin resonance (ESR) dosimetry using dental enamels

    International Nuclear Information System (INIS)

    Dose in teeth was studied to develop a method that can predict effective dose from results by the Electron Spin Resonance (ESR) dosimetry using dental enamels for external photon exposure. Absorbed dose in teeth and effective dose were calculated by the Electron Gamma Shower Code Version 4 (EGS4). In the Monte Carlo calculations, a region for teeth was newly added to a mathematical human model. Experiments were carried out with a head phantom, which is made of tissue equivalent materials. ESR dosimetry was made with dental enamels irradiated at teeth-part in the head phantom. The absorbed dose in a mouth was also measured with TLDs exposed to gamma rays as the teeth. The Monte Carlo calculation and the experiment gave a quantitative relationship between absorbed dose in teeth and effective dose. The obtained data are considered to be useful for the retrospective individual dose assessment with ESR dosimetry using dental enamels. (author)

  13. Biological radiation dose from secondary particles in a Milky Way gamma ray burst

    CERN Document Server

    Atri, Dimitra; Karam, Andrew

    2013-01-01

    Gamma ray bursts (GBRs) are a class of highly energetic explosions emitting radiation in a very short timescale of a few seconds and with a very narrow opening angle. Although, all GRBs observed so far are extragalactic in origin, there is a high probability of a GRB of galactic origin beaming towards the Earth in the past ~ 0.5 Gyr. Such an intense burst of gamma rays would ionize the atmosphere and deplete the ozone layer. With depleted ozone, there will be an increased flux of solar UVB on the Earth\\~Os surface with harmful biological effects. In addition to the atmospheric damage, secondary particles produced by gamma ray-induced showers will reach the surface. Amongst all secondary particles, muons dominate the ground-level secondary particle flux (99% of the total number of particles) and are potentially of biological significance. Using the Monte Carlo simulation code CORSIKA, we modeled the air showers produced by gamma ray primaries up to 100 GeV. We found that the number of muons produced by hypothe...

  14. Biological effects of space radiation and development of effective countermeasures

    Science.gov (United States)

    Kennedy, Ann R.

    2014-04-01

    As part of a program to assess the adverse biological effects expected from astronauts' exposure to space radiation, numerous different biological effects relating to astronauts' health have been evaluated. There has been major focus recently on the assessment of risks related to exposure to solar particle event (SPE) radiation. The effects related to various types of space radiation exposure that have been evaluated are: gene expression changes (primarily associated with programmed cell death and extracellular matrix (ECM) remodeling), oxidative stress, gastrointestinal tract bacterial translocation and immune system activation, peripheral hematopoietic cell counts, emesis, blood coagulation, skin, behavior/fatigue (including social exploration, submaximal exercise treadmill and spontaneous locomotor activity), heart functions, alterations in biological endpoints related to astronauts' vision problems (lumbar puncture/intracranial pressure, ocular ultrasound and histopathology studies), and survival, as well as long-term effects such as cancer and cataract development. A number of different countermeasures have been identified that can potentially mitigate or prevent the adverse biological effects resulting from exposure to space radiation.

  15. Microwave radiation: biological effects and exposure standards

    Energy Technology Data Exchange (ETDEWEB)

    Lindsay, I.R.

    1981-01-01

    The thermal effects of microwave radiation are well recognized and are discussed with particular reference to cataractogenesis; the possibility of an association cannot be questioned. Postulated nonthermal effects comprise an asthenic syndrome, and for the most part the disturbances lie within clinical norms and tolerances, and are reversible. World opinion on safe exposure levels for microwave radiation is varied, and this had led to national standards disparate by three to four orders of magnitude. The US and UK exposure standard of 10 mW/cm/sup 2/ was determined over two decades ago; the possibility of a change to a more restrictive level, in line with other countries, in the near future is examined. It is concluded that such a change, without scientific rationale, is not justified. Some biological implications of the microwave radiation from the solar power satellite are considered in terms of precautions to be taken by personnel working in the vicinity of the rectenna, effects on cardiac pacemakers, and any potential effects on birds. 14 references.

  16. Stunning effects after a diagnostic dose of iodine-131

    International Nuclear Information System (INIS)

    Aim: To understand stunning effects of a diagnostic dose of iodine-131 (I-131). Methods: Four hundred and sixty-eight patients (101 males, 367 females, ages: 6-75 years) with well differentiated thyroid cancer, following total or nearly total thyroidectomy, were studied. One hundred and eleven MBq (3 mCi) diagnostic (Dx) doses of I-131 whole body scan (WBS) were obtained after withholding thyroxine after 6 weeks and triiodothyronine for 2 weeks. One week to one month later, 3.7-7.4 GBq (100-200 mCi) I-131 was given to them, then a therapeutic (Tx) dose of I-131 WBS was performed. The serum thyroid simulating hormone level was usually above 30 μIU/ml. Results: Of the 468 patients, 344 (73.5%) had scintigraphic patterns of apparently decreased uptake in 240 thyroid remnants and 104 metastatic lesions on the Tx dose of I-131 WBS compared to Dx dose of I-131 WBS. Stunning phenomenon occured in 50 cases, including 42 thyroid remnants and 18 metastatic lesions. Conclusion: Dx dose of I-131 may influence the uptake of a subsequently adminstered Tx dose of I-131. (orig.)

  17. Contrast media: Biologic effects and clinical application

    International Nuclear Information System (INIS)

    An overview is presented of the recent developments in contrast media and their clinical applications, plus the current state-of-the-art in computerized tomography, digital subtraction angiography, ultrasound and magnetic resonance imaging (MRI). Contents of these volumes include: an in-depth review of the historical development, modern perspectives in structure-function relationships, biologic effects on hemostats, gastrointestinal, cardiovascular systems and drug interactions. Critical and basic issues, including cellular toxicity, mutagenesis, synergism between radiation and contrast agents, mechanisms in contrast-induced reactions, and the management of such reactions in high-risk patients are also presented. Specific applications of paramagnetic compounds in MRI and the recent concept of liposome-encapsulated and particulate suspension of contrast materials in diagnostic imaging are thoroughly discussed

  18. Contrast media: Biologic effects and clinical application

    Energy Technology Data Exchange (ETDEWEB)

    Parvez, Z.; Moncada, R.; Sovak, M.

    1987-01-01

    An overview is presented of the recent developments in contrast media and their clinical applications, plus the current state-of-the-art in computerized tomography, digital subtraction angiography, ultrasound and magnetic resonance imaging (MRI). Contents of these volumes include: an in-depth review of the historical development, modern perspectives in structure-function relationships, biologic effects on hemostats, gastrointestinal, cardiovascular systems and drug interactions. Critical and basic issues, including cellular toxicity, mutagenesis, synergism between radiation and contrast agents, mechanisms in contrast-induced reactions, and the management of such reactions in high-risk patients are also presented. Specific applications of paramagnetic compounds in MRI and the recent concept of liposome-encapsulated and particulate suspension of contrast materials in diagnostic imaging are thoroughly discussed.

  19. Dose-effect relationships for the US radium dial painters

    International Nuclear Information System (INIS)

    Dose-response data are presented from a large percentage of the US workers who were exposed to radium through the painting of luminous dials. The data in this paper are only from females, because very few males worked in this occupation. Log-normal analyses were done for radium-induced bone sarcomas and head carcinomas after the populations of the respective doses were first determined to be log-normally distributed. These populations included luminisers who expressed no radium-related cancerous condition. In this study of the female radium luminisers, the most important data concerning radiation protection are probably from workers who were exposed to radium but showed no cancer incidence. A total of 1391 subjects with average measured skeletal doses below 10 Gy are in this category. A primary purpose is to illustrate the strong case that 226,228Ra is representative of those radionuclides that exemplify in humans a 'threshold' dose, a dose below which there has been no observed health effects on the exposed individual. Application of a threshold dose for radium deposited in the skeleton does not mean to imply that any other source of skeletal irradiation should be considered to follow a similar pattern. Second, a policy issue that begs for attention is the economic consequence of forcing radiation to appear as a highly toxic insult. It is time to evaluate the data objectively instead of formatting the extrapolation scheme beforehand and forcing the data to fit a preconceived pattern such as linearity through the dose-effect origin. In addition, it is time to re-evaluate (again) variations in background radiation levels throughout the world and to cease being concerned with, and regulating against, miniscule doses for which no biomedical effects on humans have ever been satisfactorily identified or quantified. (author)

  20. Food irradiation and its biological effects

    International Nuclear Information System (INIS)

    Irradiation of foods drew attention mostly in 1960s for disinfestation of food grains, spices and sprout inhibition in mainly potato and onion. γ-irradiation at 0.25 to 1 kGy dosage levels are usually used for irradiating grains, legumes, spices and sprout-prone vegetables. Irradiation of foods with in permissible dosage levels of 0.25 to 5 kGy is usually considered fairly safe from human consumption point of view not withstanding usual health concerns about its usage in foods. Irradiation of foods, in mostly solid or semi-solid form, at 5 kGy levels of γ-irradiation can achieve radicidation or, radiation equivalent of pasteurization and, if γ-irradiation is used at 10 kGy, it can achieve radappertization or, radiation equivalent of thermal commercial sterilization. However, the food industry uses γ-irradiation at 0.25 to 2 kGy only for mostly disinfestation of food grains/legumes, spices, sprout inhibition in potato and onion and, for surface sanitation of frozen fish, poultry and meat. Exposure to irradiation creates free radicals in foods that are capable of destroying some of the spoilage and pathogenic microflora but the same can also damage vitamins and enzymes besides creating some new harmful new chemical species, called unique radiolytic products (URPs), by combining with certain chemicals that a food may be laced with (like pesticides/fungicides). Exposure to high-energy electron beams are also known to create deleterious biological effects which may even lead to detection of trace amounts of radioactivity in the food. Some possible causes delineated for such harmful biological effects of irradiation include: irradiation induced vitamin deficiencies, the inactivity of enzymes in the foods, DNA damage and toxic radiolytic products in the foods. Irradiation, a non-thermal food preservation technique, has a role in salvaging enormous post harvest losses (25-30%) in developing economies to increase the per capita availability of foods. (author)

  1. Relative biological effectiveness and radiation weighting factors in the context of animals and plants

    International Nuclear Information System (INIS)

    Radiation weighting factors have long been employed to modify absorbed dose as part of the process of evaluating radiological impact to humans. Their use represents an acknowledgement of the fundamental difference in energy deposition patterns of charged and uncharged particles, and how this can translate into varying degrees of biological impact. Weighting factors used in human radiation protection are derived from a variety of endpoints taken from in-vitro experiments that include human and animal cell lines, as well as in-vivo experiments with animals. Nonetheless, the application of radiation weighting factors in the context of dose assessment of animals and plants is not without some controversy. Specifically, radiation protection of biota has largely focused on limiting deterministic effects, such as reduced reproductive fitness. Consequently, the application of conventional stochastic-based radiation weighting factors (when used for human protection) appears inappropriate. While based on research, radiation weighting factors represent the parsing of extensive laboratory studies on relative biological effectiveness. These studies demonstrate that the magnitude of a biological effect depends not just on dose, but also on other factors including the rate at which the dose is delivered, the type and energy of the radiation delivering the dose, and, most importantly, the endpoint under consideration. This article discusses the efforts taken to develop a logical, transparent, and defensible approach to establishing radiation weighting factors for use in assessing impact to non-human biota, and the challenges found in differentiating stochastic from deterministic impacts.

  2. Life-span studies in 226Ra-injected animals: Effect of low doses, effect of a decorporative treatment

    International Nuclear Information System (INIS)

    A life-span radiation effects study was performed in mice injected with several doses of 226Ra. The study included 788 male C57Bl mice. For the removal of the 226Ra, half the mice were treated daily with a diet 5% of which was sodium-alginate. The experiment revealed that mice that received the lowest dose of 226Ra lived significantly longer than controls, and, despite appreciable skeletal removal of 226Ra as a result of decorporative treatment, no biological benefit was observed in treated animals. 19 refs., 4 figs., 3 tabs

  3. A Novel Biological Dosimetry Method for Monitoring Occupational Radiation Exposure in Diagnostic and Therapeutic Wards: From Radiation Dosimetry to Biological Effects

    OpenAIRE

    Heydarheydari, S.; Haghparast, A.; Eivazi, M.T.

    2016-01-01

    Background and Objective Professional radiation workers are occupationally exposed to long-term low levels of ionizing radiation. Occupational health hazards from radiation exposure, in a large occupational segment of the population, are of special concern. Biological dosimetry can be performed in addition to physical dosimetry with the aim of individual dose assessment and biological effects. Methods In this biodosimetry study, some hematological parameters have been examined in 40 exposed a...

  4. SU-E-T-500: Dose Escalation Strategy for Lung Cancer Patients Using a Biologically- Guided Target Definition

    International Nuclear Information System (INIS)

    Purpose: Dose escalation strategy for lung cancer patients can lead to late symptoms such as pneumonitis and cardiac injury. We propose a strategy to increase radiation dose for improving local tumor control while simultaneously striving to minimize the injury of organs at risk (OAR). Our strategy is based on defining a small, biologically-guided target volume for receiving additional radiation dose. Methods: 106 patients with lung cancer treated with radiotherapy were selected for patients diagnosed with stage II and III disease. Previous research has shown that 50% of the maximum SUV threshold in FDG-PET imaging is appropriate for delineation of the most aggressive part of a tumor. After PET- and CT-derived targets were contoured, an IMRT treatment plan was designed to deliver 60 Gy to the GTV as delineated on a 4D CT (Plan 1). A second plan was designed with additional dose of 18 Gy to the PET-derived volume (Plan 2). A composite plan was generated by the addition of Plan 1 and Plan 2. Results: Plan 1 was compared to the composite plan and increases in OAR dose were assessed. For seven patients on average, lung V5 was increased by 1.4% and V20 by 4.2% for ipsilateral lung and by 13.5% and 7% for contralateral lung. For total lung, V5 and V20 were increased by 4.5% and 4.8% respectively. Mean lung dose was increased by 9.7% for the total lung. The maximum dose to the spinal cord increased by 16% on average. For the heart, V20 increased by 4.2% and V40 by 5.2%. Conclusion: It seems feasible that an additional 18 Gy of radiation dose can be delivered to FDG PET-derived subvolume of the CT-based GTV of the primary tumor without significant increase in total dose to the critical organs such as lungs, spinal cord and heart

  5. SU-E-T-500: Dose Escalation Strategy for Lung Cancer Patients Using a Biologically- Guided Target Definition

    Energy Technology Data Exchange (ETDEWEB)

    Shusharina, N; Khan, F; Choi, N; Sharp, G [Massachusetts General Hospital, Boston, MA (United States)

    2014-06-01

    Purpose: Dose escalation strategy for lung cancer patients can lead to late symptoms such as pneumonitis and cardiac injury. We propose a strategy to increase radiation dose for improving local tumor control while simultaneously striving to minimize the injury of organs at risk (OAR). Our strategy is based on defining a small, biologically-guided target volume for receiving additional radiation dose. Methods: 106 patients with lung cancer treated with radiotherapy were selected for patients diagnosed with stage II and III disease. Previous research has shown that 50% of the maximum SUV threshold in FDG-PET imaging is appropriate for delineation of the most aggressive part of a tumor. After PET- and CT-derived targets were contoured, an IMRT treatment plan was designed to deliver 60 Gy to the GTV as delineated on a 4D CT (Plan 1). A second plan was designed with additional dose of 18 Gy to the PET-derived volume (Plan 2). A composite plan was generated by the addition of Plan 1 and Plan 2. Results: Plan 1 was compared to the composite plan and increases in OAR dose were assessed. For seven patients on average, lung V5 was increased by 1.4% and V20 by 4.2% for ipsilateral lung and by 13.5% and 7% for contralateral lung. For total lung, V5 and V20 were increased by 4.5% and 4.8% respectively. Mean lung dose was increased by 9.7% for the total lung. The maximum dose to the spinal cord increased by 16% on average. For the heart, V20 increased by 4.2% and V40 by 5.2%. Conclusion: It seems feasible that an additional 18 Gy of radiation dose can be delivered to FDG PET-derived subvolume of the CT-based GTV of the primary tumor without significant increase in total dose to the critical organs such as lungs, spinal cord and heart.

  6. Effects of low dose radiation and epigenetic regulation

    International Nuclear Information System (INIS)

    Purpose: To conclude the relationship between epigenetics regulation and radiation responses, especially in low-dose area. Methods: The literature was examined for papers related to the topics of DNA methylation, histone modifications, chromatin remodeling and non-coding RNA modulation in low-dose radiation responses. Results: DNA methylation and radiation can regulate reciprocally, especially in low-dose radiation responses. The relationship between histone methylation and radiation mainly exists in the high-dose radiation area; histone deacetylase (HDAC) inhibitors show a promising application to enhance radiation sensitivity, no matter whether in low-dose or high-dose areas; the connection between γ-H2AX and LDR has been remained unknown, although γ-H2AX has been shown no radiation sensitivities with 1-15 Gy irradiation; histone ubiquitination play an important role in DNA damage repair mechanism. Moreover, chromatin remodeling has an integral role in DSB repair and the chromatin response, in general, may be precede DNA end resection. Finally, the effect of radiation on miRNA expression seems to vary according to cell type, radiation dose, and post-irradiation time point. Conclusion: Although the advance of epigenetic regulation on radiation responses, which we are managing to elucidate in this review, has been concluded, there are many questions and blind blots deserved to investigated, especially in low-dose radiation area. However, as progress on epigenetics, we believe that many new elements will be identified in the low-dose radiation responses which may put new sights into the mechanisms of radiation responses and radiotherapy. (authors)

  7. Application of a sitting MIRD phantom for effective dose calculations

    International Nuclear Information System (INIS)

    In typical realistic scenarios, dose factors due to 60Co contaminated steel, used in consumer products, cannot be approximated by standard exposure geometries. It is then necessary to calculate the effective dose using an appropriate anthropomorphic phantom. MCNP calculations were performed using a MIRD human model in two settings. In the first, a male office worker is sitting in a chair containing contaminated steel, surrounded by contaminated furniture. In the second, a male driver is seated inside an automobile, the steel of which is uniformly contaminated. To accurately calculate the dose to lower body organs, especially the gonads, it was essential to modify the MIRD model to simulate two sitting postures: chair and driving position. The phantom modifications are described, and the results of the calculations are presented. In the case of the automobile scenarios, results are compared to those obtained using an isotropic fluence-to-dose conversion function. (authors)

  8. Dose-dependent Effects of mTOR Inhibition on Weight and Mitochondrial Disease in Mice

    Directory of Open Access Journals (Sweden)

    Simon C Johnson

    2015-07-01

    Full Text Available Rapamycin extends lifespan and attenuates age-related pathologies in mice when administered through diet at 14 parts per million (PPM. Recently, we reported that daily intraperitoneal injection of rapamycin at 8 mg/kg attenuates mitochondrial disease symptoms and progression in the Ndufs4 knockout mouse model of Leigh Syndrome. Although rapamycin is a widely used pharmaceutical agent dosage has not been rigorously examined and no dose-response profile has been established. Given these observations we sought to determine if increased doses of oral rapamycin would result in more robust impact on mTOR driven parameters. To test this hypothesis, we compared the effects of dietary rapamycin at doses ranging from 14 to 378 PPM on growth in control and Ndufs4 knockout mice and on health and survival in the Ndufs4 knockout model. High dose rapamycin was well tolerated, dramatically reduced growth, and overcame gender differences. The highest oral dose, approximately 27-times the dose shown to extend murine lifespan, increased survival in Ndufs4 knockout mice similarly to daily rapamycin injection without observable adverse effects. These findings have broad implications for the effective use of rapamycin in murine studies and for the translational potential of rapamycin in the treatment of mitochondrial disease. This data, further supported by a comparison of available literature, suggests that 14 PPM dietary rapamycin is a sub-optimal dose for targeting mTOR systemically in mice. Our findings suggest that the role of mTOR in mammalian biology may be broadly underestimated when determined through treatment with rapamycin at commonly used doses.

  9. MO-G-BRF-09: Investigating Magnetic Field Dose Effects in Mice: A Monte Carlo Study

    Energy Technology Data Exchange (ETDEWEB)

    Rubinstein, A; Guindani, M; Followill, D; Melancon, A; Hazle, J; Court, L [UT MD Anderson Cancer Center, Houston, TX (United States)

    2014-06-15

    Purpose: In MRI-linac treatments, radiation dose distributions are affected by magnetic fields, especially at high-density/low-density interfaces. Radiobiological consequences of magnetic field dose effects are presently unknown; therefore, preclinical studies are needed to ensure the safe clinical use of MRI-linacs. This study investigates the optimal combination of beam energy and magnetic field strength needed for preclinical murine studies. Methods: The Monte Carlo code MCNP6 was used to simulate the effects of a magnetic field when irradiating a mouse-sized lung phantom with a 1.0cmx1.0cm photon beam. Magnetic field effects were examined using various beam energies (225kVp, 662keV[Cs-137], and 1.25MeV[Co-60]) and magnetic field strengths (0.75T, 1.5T, and 3T). The resulting dose distributions were compared to Monte Carlo results for humans with various field sizes and patient geometries using a 6MV/1.5T MRI-linac. Results: In human simulations, the addition of a 1.5T magnetic field caused an average dose increase of 49% (range:36%–60%) to lung at the soft tissue-to-lung interface and an average dose decrease of 30% (range:25%–36%) at the lung-to-soft tissue interface. In mouse simulations, the magnetic fields had no effect on the 225kVp dose distribution. The dose increases for the Cs-137 beam were 12%, 33%, and 49% for 0.75T, 1.5T, and 3.0T magnetic fields, respectively while the dose decreases were 7%, 23%, and 33%. For the Co-60 beam, the dose increases were 14%, 45%, and 41%, and the dose decreases were 18%, 35%, and 35%. Conclusion: The magnetic field dose effects observed in mouse phantoms using a Co-60 beam with 1.5T or 3T fields and a Cs-137 beam with a 3T field compare well with those seen in simulated human treatments with an MRI-linac. These irradiator/magnet combinations are suitable for preclinical studies investigating potential biological effects of delivering radiation therapy in the presence of a magnetic field. Partially funded by Elekta.

  10. biological and biomatrial effects of gamma radiation on the mosquito Culex Pipiens L. Vol. 4

    International Nuclear Information System (INIS)

    The mosquito, Culex Pipiens L. Was irradiated in the pupal stage with three gamma doses (40, 60 and 80 Gy). The effect of irradiation on the biology and ovarian development of the adult stage were assayed in comparison with a non-irradiated control group. The results showed that the gamma doses used decreased significantly adult emergence and increased malformations, while the sex ratio was not affected. fecundity of irradiated females was severely affected at 40 and 60 Gy, and 80 Gy produced in fecund females. Egg hatch ability was severely affected when males were irradiated at all doses. The gamma doses used decreased the number of ovarioles that reached the 5 th stage of christopher cycle. these ovarioles failed to produce mature eggs normally. The size of the irradiated female ovary was decreased either in length or in width at all doses used particularly at 80 Gy where the ovarian development was completely stopped on the first day of feeding. 6 figs

  11. Ionol [BHT]. Distribution in the organism, metabolism, and biological effect. II. Biological effects of ionol (survey)

    International Nuclear Information System (INIS)

    In these experiments, a 25 mg/kg dose of ionol, administered to mice immediately after transplantation of melanoma B-16 or injection of tumor cells, inhibited the growth of pigmented B-16 cells and somewhat decreased the number of metastases. Ionol inhibited the mutagenic effect of benz(a)pyrene in vitro and in a culture of Salmonella typhimurium. In a mix with butylhydroxyanisole and propyl gallate, it decreased the number of mutations induced by gamma irradiation in the same culture. It protected mice from dominant lethal mutations and hereditary translocations induced by ethyl methanesulfonate (EMS). When ionol was present in the feed in a dose of 0.75% it reduced the lethal effect in mice of dimethylnitrosamine, EMS, ethylene dibromide and cyclophosphamide

  12. Estimating effective doses to children from CT examinations

    International Nuclear Information System (INIS)

    Full text: Assessing doses to patients in diagnostic radiology is an integral part of implementing optimisation of radiation protection. Sources of normalised data are available for estimating doses to adults undergoing CT examinations, but for children this is not the case. This paper describes a simple method for estimating effective doses arising from paediatric CT examinations. First the effective dose to an adult is calculated, having anatomically matched the scanned regions of the child and the adult and also matched the irradiation conditions. A conversion factor is then applied to the adult effective dose, based on the region of the body being scanned - head, upper or lower trunk. This conversion factor is the child-to-adult ratio of the ratios of effective dose per entrance air kerma (in the absence of the patient) at the FAD. The values of these conversion factors were calculated by deriving effective dose per entrance air kerma at the FAD for new-born, 1, 5, 10, 15 and adult phantoms using four projections (AP, PA, left and right laterals) over a range of beam qualities and FADs.The program PCXMC was used for this purpose. Results to date suggest that the conversion factors to give effective doses for children undergoing CT examinations of the upper trunk are approximately 1.3, 1.2, 1.15, 1.1 and 1.05 for ages 0, 1, 5, 10 and 15 years respectively; CT of the lower trunk - 1.4, 1.3, 1.2, 1.2, 1.1; and CT of the head - 2.3, 2.0, 1.5, 1.3, 1.1. The dependence of these factors on beam quality (HVL from 4 to 10 mm Al) is less than 10%, with harder beams resulting in slightly smaller conversion factors. Dependence on FAD is also less than 10%. Major sources of uncertainties in the conversion factors include matching anatomical regions across the phantoms, and the presence of beam divergence in the z-direction when deriving the factors. The method described provides a simple means of estimating effective doses arising from paediatric CT examinations with

  13. Contribution of the modulation of intensity and the optimization to deliver a dose adapted to the biological heterogeneities; Apport de la modulation d'intensite et de l'optimisation pour delivrer une dose adaptee aux heterogeneites biologiques

    Energy Technology Data Exchange (ETDEWEB)

    Kubs, F

    2007-10-15

    The recent progress in functional imaging by Positron Emission Tomography (TEP) opens new perspectives in the delineation of target volumes in radiotherapy. The functional data is major; we can intend to adapt the irradiation doses on the tumor activity (TA) and to perform a dose escalation. Our objectives were (i) to characterize the TEP threshold, by quantifying the uncertainties of the target volume contour according to the lesion size and the threshold contour level, (ii) to set up the geometry suited to perform a high-precision irradiation based on the TA, (iii) to estimate the dosimetric impact of this new protocol and (iv) to verify that dosimetry is perfectly distributed. Three original phantoms were specially created to satisfy the constraints met, as well as two virtual phantoms containing 3 dose levels (dose level 3 = TA). Our results showed the importance of the effect threshold-volume on the planning in radiotherapy. To use this irradiation method, the diameter of 1 cm for the third level was able to be reached. A dose escalation of 20 Gy was possible between the second (70 Gy) and the third level (90 Gy). The dosimetric impact estimated on two real cases was suitable - increase of COIN (conformal index) from 0.6 to 0.8 and decrease of NTCP (normal tissue complication probability) of a factor 5 -. In absolute and relative dosimetry, the clinical tolerances were respected. So all the treatment process, going from the diagnosis with the TEP to reveal the TA, to the patient treatment made beforehand on phantom, and going through the ballistic and the dose calculation, was estimated and validated according to our objective to adapt the irradiation to the biological heterogeneities. However such high doses should be carefully estimated before being prescribed clinically and progress is also expected in imaging, because the minimal size which we can irradiate is on the limit of the resolution TEP. (author)

  14. Cost-effectiveness of reduction of off-site dose

    International Nuclear Information System (INIS)

    Since the early 1970's, nuclear power plants have been designed and operated with a target of not releasing more than one percent of the licensed limits (derived emission limits) in liquid and gaseous effluents. The AECB initiated this study of the cost-effectiveness of the reduction of off-site doses as part of a review to determine if further measures to reduce off-site doses might be reasonably achievable. Atlantic Nuclear has estimated the cost of existing technology options that can be applied for a further reduction of radioactive effluents from future CANDU nuclear power plants. Detritiation, filtration, ion exchange and evaporation are included in the assessment. The costs are presented in 1987 Canadian dollars, and include capital and operating costs for a reference 50 year plant life. Darlington NGS and Point Lepreau NGS are the reference nuclear power plant types and locations. The effect resulting from the hypothetical application of each technology has been calculated as the resulting reduction in world collective radiation dose detriment. The CSA N288.1 procedure was used for local pathway analysis and the global dispersion model developed by the NEA (OECD) group of experts was used for dose calculations. The reduction in the 'collective effective dose equivalent commitment' was assumed to exist for 10,000 years, the expected life-span of solid waste repositories. No attempt was made to model world population dynamics. The collective dose reductions were calculated for a nominal world population of 10 billion persons. The estimated cost and effect of applying the technology options are summarized in a tabular form for input to further consideration of 'reasonably achievable off-site dose levels'

  15. Thermal dose requirement for tissue effect: experimental and clinical findings

    Science.gov (United States)

    Dewhirst, Mark; Viglianti, Benjamin L.; Lora-Michiels, Michael; Hoopes, P. Jack; Hanson, Margaret A.

    2003-06-01

    In this review we have summarized the basic principles that govern the relationships between thermal exposure (temperature and time of exposure) and thermal damage, with an emphasis on normal tissue effects. We have also attempted to identify specific thermal dose information (for safety and injury) for a variety of tissues in a variety of species. We address the use, accuracy and difficulty of conversion of an individual time and temperature (thermal dose) to a standardized value (eg equivalent minutes at 43degC) for comparison of thermal treatments. Although, the conversion algorithm appears to work well within a range of moderately elevated temperatures (2-15degC) above normal physiologic baseline (37-39degC) there is concern that conversion accuracy does not hold up for temperatures which are minimally or significantly above baseline. An extensive review of the literature suggests a comprehensive assessment of the "thermal dose-to-tissue effect" has not previously been assembled for most individual tissues and never been viewed in a semi-comprehensive (tissues and species) manner. Finally, we have addressed the relationship of thermal dose-to-effect vs. baseline temperature. This issues is important since much of the thermal dose-to-effect information has been accrued in animal models with baseline temperatures 1-2 deg higher than that of humans.

  16. Stochastic Effects in Computational Biology of Space Radiation Cancer Risk

    Science.gov (United States)

    Cucinotta, Francis A.; Pluth, Janis; Harper, Jane; O'Neill, Peter

    2007-01-01

    Estimating risk from space radiation poses important questions on the radiobiology of protons and heavy ions. We are considering systems biology models to study radiation induced repair foci (RIRF) at low doses, in which less than one-track on average transverses the cell, and the subsequent DNA damage processing and signal transduction events. Computational approaches for describing protein regulatory networks coupled to DNA and oxidative damage sites include systems of differential equations, stochastic equations, and Monte-Carlo simulations. We review recent developments in the mathematical description of protein regulatory networks and possible approaches to radiation effects simulation. These include robustness, which states that regulatory networks maintain their functions against external and internal perturbations due to compensating properties of redundancy and molecular feedback controls, and modularity, which leads to general theorems for considering molecules that interact through a regulatory mechanism without exchange of matter leading to a block diagonal reduction of the connecting pathways. Identifying rate-limiting steps, robustness, and modularity in pathways perturbed by radiation damage are shown to be valid techniques for reducing large molecular systems to realistic computer simulations. Other techniques studied are the use of steady-state analysis, and the introduction of composite molecules or rate-constants to represent small collections of reactants. Applications of these techniques to describe spatial and temporal distributions of RIRF and cell populations following low dose irradiation are described.

  17. Normal tissue complication probabilities: dependence on choice of biological model and dose-volume histogram reduction scheme

    International Nuclear Information System (INIS)

    Purpose: To evaluate the impact of dose-volume histogram (DVH) reduction schemes and models of normal tissue complication probability (NTCP) on ranking of radiation treatment plans. Methods and Materials: Data for liver complications in humans and for spinal cord in rats were used to derive input parameters of four different NTCP models. DVH reduction was performed using two schemes: 'effective volume' and 'preferred Lyman'. DVHs for competing treatment plans were derived from a sample DVH by varying dose uniformity in a high dose region so that the obtained cumulative DVHs intersected. Treatment plans were ranked according to the calculated NTCP values. Results: Whenever the preferred Lyman scheme was used to reduce the DVH, competing plans were indistinguishable as long as the mean dose was constant. The effective volume DVH reduction scheme did allow us to distinguish between these competing treatment plans. However, plan ranking depended on the radiobiological model used and its input parameters. Conclusions: Dose escalation will be a significant part of radiation treatment planning using new technologies, such as 3-D conformal radiotherapy and tomotherapy. Such dose escalation will depend on how the dose distributions in organs at risk are interpreted in terms of expected complication probabilities. The present study indicates considerable variability in predicted NTCP values because of the methods used for DVH reduction and radiobiological models and their input parameters. Animal studies and collection of standardized clinical data are needed to ascertain the effects of non-uniform dose distributions and to test the validity of the models currently in use

  18. Soil biochar amendments: type and dose effects

    Science.gov (United States)

    Ojeda, G.; Domene, X.; Mattana, S.; Sousa, J. P.; Ortiz, O.; Andres, P.; Alcañiz, J. M.

    2012-04-01

    Biochar is an organic material produced via the pyrolysis of C-based biomass, which is increasingly being recognized by scientists and policy makers for its potential role in carbon sequestration, reducing greenhouse gas emissions, waste mitigation, and as a soil amendment. Recent studies indicated that biochar improves soil fertility through its positive influence on physical-chemical properties, since not only improves water retention, aggregation and permeability, but its high charge density can also hold large amounts of nutrients, increasing crop production. However, it was observed that combustion temperature could affects the degree of aromaticity and the size of aromatic sheets, which in turns determine short-term mineralization rates. To reconcile the different decompasibility observations of biochar, it has sugested that physical protection and interactions with soil minerals play a significant part in biochar stability. In this context, it has initiated one pilot studies which aims to assess the effects of biochar application on physical and chemical properties of agricultural soil under Mediterranean conditions, such as changes in aggregate formation, intra-aggregate carbon sequestration and chemistry of soil water. In the present study, different clases of biochar produced from fast, slow and gasification pyrolisis of vegetal (pine, poplar) and dried sludge biomass, were applied at 1% of biochar-C to mesocosmos of an agricultural soil. Preliminary, it must be pointed out that slow and gasification pyrolisis changes the proportion of particles < 2 mm in diameter, from 10% (original materials) to almost 100%. In contrast, slow pyrolisis not modifies significantly biochar granulometry. As a consequence, bulk density of poplar and pine splinters decreases after fast pyrolisis. Regarding to organic carbon contents of biochar, all biochars obtained from plant biomass presented percentagens of total organic carbon (TOC) between 70 - 90%, while biochar

  19. Radon exposure of the skin: I. Biological effects

    Energy Technology Data Exchange (ETDEWEB)

    Charles, M W [School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom)

    2007-09-15

    Radon progeny can plate out on skin and give rise to exposure of the superficial epidermis from alpha emitters Po-218 (7.7 MeV, range {approx}66 {mu}m) and Po-214 (6 MeV, range {approx}44 {mu}m). Dose rates from beta/gamma emitters Pb-214 and Bi-214 are low and only predominate at depths in excess of the alpha range. This paper reviews the evidence for a causal link between exposure from radon and its progeny, and deterministic and stochastic biological effects in human skin. Radiation induced skin effects such as ulceration and dermal atrophy, which require irradiation of the dermis, are ruled out for alpha irradiation from radon progeny because the target cells are considerably deeper than the range of alpha particles. They have not been observed in man or animals. Effects such as erythema and acute epidermal necrosis have been observed in a few cases of very high dose alpha particle exposures in man and after acute high dose exposure in animals from low energy beta radiations with similar depth doses to radon progeny. The required skin surface absorbed doses are in excess of 100 Gy. Such effects would require extremely high levels of radon progeny. They would involve quite exceptional circumstances, way outside the normal range of radon exposures in man. There is no definitive identification of the target cells for skin cancer induction in animals or man. The stem cells in the basal layer which maintain the epidermis are the most plausible contenders for target cells. The majority of these cells are near the end of the range of radon progeny alpha particles, even on the thinnest body sites. The nominal depth of these cells, as recommended by the International Commission on Radiological Protection (ICRP), is 70 {mu}m. There is evidence however that some irradiation of the hair follicles and/or the deeper dermis, as well as the inter-follicular epidermis, is also necessary for skin cancer induction. Alpha irradiation of rodent skin that is restricted to the

  20. Radon exposure of the skin: I. Biological effects

    International Nuclear Information System (INIS)

    Radon progeny can plate out on skin and give rise to exposure of the superficial epidermis from alpha emitters Po-218 (7.7 MeV, range ∼66 μm) and Po-214 (6 MeV, range ∼44 μm). Dose rates from beta/gamma emitters Pb-214 and Bi-214 are low and only predominate at depths in excess of the alpha range. This paper reviews the evidence for a causal link between exposure from radon and its progeny, and deterministic and stochastic biological effects in human skin. Radiation induced skin effects such as ulceration and dermal atrophy, which require irradiation of the dermis, are ruled out for alpha irradiation from radon progeny because the target cells are considerably deeper than the range of alpha particles. They have not been observed in man or animals. Effects such as erythema and acute epidermal necrosis have been observed in a few cases of very high dose alpha particle exposures in man and after acute high dose exposure in animals from low energy beta radiations with similar depth doses to radon progeny. The required skin surface absorbed doses are in excess of 100 Gy. Such effects would require extremely high levels of radon progeny. They would involve quite exceptional circumstances, way outside the normal range of radon exposures in man. There is no definitive identification of the target cells for skin cancer induction in animals or man. The stem cells in the basal layer which maintain the epidermis are the most plausible contenders for target cells. The majority of these cells are near the end of the range of radon progeny alpha particles, even on the thinnest body sites. The nominal depth of these cells, as recommended by the International Commission on Radiological Protection (ICRP), is 70 μm. There is evidence however that some irradiation of the hair follicles and/or the deeper dermis, as well as the inter-follicular epidermis, is also necessary for skin cancer induction. Alpha irradiation of rodent skin that is restricted to the epidermis does not

  1. Effective dose and risks from medical x-ray procedures

    International Nuclear Information System (INIS)

    The radiation risks from a range of medical x-ray examinations (radiography, fluoroscopy, and computed tomography) were assessed as a function of the age and sex of the patient using risk models described in Publication 103 (ICRP, 2007) and UNSCEAR (2006, Annex A). Such estimates of risk based on typical organ doses were compared with those derived from effective doses using the International Commission on Radiological Protection’s nominal risk coefficients. Methodologically similar but not identical dose and risk calculations were performed independently at the Institute of Radiation Hygiene (Russia) and the Health Protection Agency (UK), and led to similar conclusions. The radiogenic risk of stochastic health effects following various x-ray procedures varied significantly with the patient’s age and sex, but to differing degrees depending on which body organs were irradiated. In general, the risks of radiation-induced stochastic health effects in children are estimated to be higher (by a factor of ⩽4) than in adults, and risks in senior patients are lower by a factor of ⩾10 relative to younger people. If risks are assessed on the basis of effective dose, they are underestimated for children of both sexes by a factor of ⩽4. This approach overestimates risks by a factor of ⩽3 for adults and about an order of magnitude for senior patients. The significant sex and age dependence of radiogenic risk for different cancer types is an important consideration for radiologists when planning x-ray examinations. Whereas effective dose was not intended to provide a measure of risk associated with such examinations, it may be sufficient to make simple adjustments to the nominal risk per unit effective dose to account for age and sex differences.

  2. Effects of target size on the comparison of photon and charged particle dose distributions

    International Nuclear Information System (INIS)

    The work presented here is part of an ongoing project to quantify and evaluate the differences in the use of different radiation types and irradiation geometries in radiosurgery. We are examining dose distributions for photons using the ''Gamma Knife'' and the linear accelerator arc methods, as well as different species of charged particles from protons to neon ions. A number of different factors need to be studied to accurately compare the different modalities such as target size, shape and location, the irradiation geometry, and biological response. This presentation focuses on target size, which has a large effect on the dose distributions in normal tissue surrounding the lesion. This work concentrates on dose distributions found in radiosurgery, as opposed to those usually found in radiotherapy. 5 refs., 2 figs

  3. Effects of low-dose heavy ion irradiation on male germ cell adaptation and genetics

    Institute of Scientific and Technical Information of China (English)

    ZHANG Hong; LI Wen-Jian; ZHENG Rong-Liang

    2005-01-01

    The heavy ions with high linear energy transfer and high relative biological effectiveness are much more deleterious on the male germ cells, ones of the most radiosensitive cells of the body, than low-LET ionizing radiation such as X-ray or gamma-ray. The effects of low-dose heavy ion irradiation on male germ cell adaptation and genetics and the possible mechanism of this adaptation are summarized in our laboratory. Our results showed that the heavy ion irradiation significantly increased the frequencies of chromosomal aberrations in spermatogonia and spermatocytes of mice, the low dose heavy ion irradiation could induce significant adaptative response on mouse testes and human sperm, and pre-exposure of mouse testes with low-dose heavy ion can markedly alleviate damage effects induced by subsequent high-dose irradiation. The increase of SOD activity and decrease of lipid peroxidation levels induced by low-dose ionizing radiation may be involved in this adaptative response mechanism. These studies may provide useful theoretical and clinical bases for radioprotection of reproductive potential and assessment of genetic risks for human exposed to heavy ions in radiotherapy and in outer space environment.

  4. Effects of Sublethal Dose of Imidacloprid and Pymetrozine on Relative Biological Fitness of Brown Planthopper, Nilaparvata lugens%亚致死剂量吡虫啉和吡蚜酮对褐飞虱生物适合度的影响

    Institute of Scientific and Technical Information of China (English)

    刘淑华; 杨保军; 刘双; 丁志平; 刘泽文; 唐健

    2012-01-01

    全面评价了亚致死剂量吡虫啉和吡蚜酮对褐飞虱繁殖力和生存力的长期影响.毒力测定结果显示,吡虫啉和吡蚜酮对褐飞虱3龄若虫的LC70分别为42.41mg/L.和396.46mg/L,吡虫啉毒力约是吡蚜酮毒力的9.35倍.通过建立褐飞虱在吡虫啉和吡蚜酮亚致死剂量(LC30)作用下的生命表,发现褐飞虱在两种药剂处理下生物适合度都有所下降,分别为对照试虫的83.8%和8.4%.吡虫啉处理试虫仅羽化率明显低于对照,而吡蚜酮处理试虫的羽化率、雌虫比例、雌成虫寿命和卵孵化率各参数部明显下降.亚致死剂量的吡蚜酮使褐飞虱日产卵节律和卵孵化高峰都有所推迟,这可能是吡蚜酮对褐飞虱产生取食抑制作用进而导致其生殖器官发育缓慢造成的.%Long-term influences of sublethal dose of imidacloprid and pymetrozine on reproduction and biological fitness of the brown planthopper(BPH) were evaluated. Bioassay results showed that the LC50 values for imidacloprid and pymetrozine were 42. 41 mg/L and 396. 46 mg/L, respectively, suggesting imidacloprid was approximately 9. 35 times more toxic than pymetrozine. The effects of the sublethal dose (LC30) of imidacloprid and pymetrozine on the fitness of the brown planthopper were evaluated by constructing and comparing the life tables. Results revealed that the biological fitness of BPH exposed to imidacloprid and pymetrozine had reduced to only 83. 8% and 8. 4% of the control, respectively. In imidacloprid treatment, there was only an obvious decline in emergence rate of adult. However, the emergence rate of adult, female adult ratio, female adult duration and eggs hatching rate were conspicuously reduced under pymetrozine treatment. In addition, the egg laying and fecundity fastigium of BPH exposed to sublethal pymetrozine were postponed compared to the control, which is probably correlated with the delayed development of genitalia caused by pymetrozine's feeding

  5. Bioaccumulation and biological effects in the earthworm Eisenia fetida exposed to natural and depleted uranium

    Energy Technology Data Exchange (ETDEWEB)

    Giovanetti, Anna, E-mail: anna.giovanetti@enea.i [ENEA, Institute of Radiation Protection, CR Casaccia Via Anguillarese 301, 00123 Rome (Italy); Fesenko, Sergey [International Atomic Energy Agency (IAEA), Agency' s Laboratories Seibersdorf, A-2444 Seibersdorf (Austria); Cozzella, Maria L. [ENEA, National Institute for Metrology of Ionizing Radiation, CR Casaccia Via Anguillarese 301, 00123 Rome (Italy); Asencio, Lisbet D. [Centro de Estudios Ambientales, Carretera a Castillo de Jagua, CP. 59350 C. Nuclear, Cienfuegos (Cuba); Sansone, Umberto [International Atomic Energy Agency (IAEA), Agency' s Laboratories Seibersdorf, A-2444 Seibersdorf (Austria)

    2010-06-15

    The accumulations of both natural (U) and depleted (DU) uranium in the earthworms (Eisenia fetida) were studied to evaluate corresponding biological effects. Concentrations of metals in the experimental soil ranged from 1.86 to 600 mg kg{sup -1}. Five biological endpoints: mortality, animals' weight increasing, lysosomal membrane stability by measuring the neutral red retention time (the NRRT), histological changes and genetic effects (Comet assay) were used to evaluate biological effects in the earthworms after 7 and 28 days of exposure. No effects have been observed in terms of mortality or weight reduction. Cytotoxic and genetic effects were identified at quite low U concentrations. For some of these endpoints, in particular for genetic effects, the dose (U concentration)-effect relationships have been found to be non-linear. The results have also shown a statistically significant higher level of impact on the earthworms exposed to natural U compared to depleted U.

  6. Information on biological health effects of ionizing radiation and radionuclides: the rule of a web site

    International Nuclear Information System (INIS)

    The purpose of this project is to provide a source of information on biological and health effects of radionuclides and ionizing radiation in an easy to use format. Reported work is made up of two distinct parts: data sheets for selected radionuclides and a web file. Data sheets: Specific radiation data sheets provide an overview of the properties, the environmental behaviour, the different pathways of human exposure and the biological and health consequences of selected radionuclides. Radionuclides that have been selected are those commonly dealt with in nuclear industry (and in other areas such as medicine) and released to the environment or naturally occurring (plutonium, tritium, carbon 14). Data sheets corresponding to the different radionuclides are based on the main sources of scientific information in dosimetry, epidemiology, radiobiology and radiation protection. These data sheets are intended for radiation protection specialists and physicians. They include: main physical and chemical characteristics, main radiation protection data: dose coefficients (public, workers), dose limits sources, total released estimate (nuclear industry, atmospheric tests, main pathway of human exposure and biological behaviour, biological and health effects, medical supervision, treatment a list of the main references, appendix providing accurate information. Web file: http://www-dsv.cea.fr/doc/carmin_ext/fond.php This web file provides a source of information on biological and health effects of ionizing radiation and biological basic knowledge of radiation protection. Available for consultation via Internet, compiled information provides, in a same file, subjects as varied as biological mechanisms, ionizing radiations action, biological and health effects, risk assessment This file is mainly intended to assist in informing and training of non-specialist readership (students, teaching on radiation protection basic knowledge. This electronic document is divided in three

  7. Exposure to low dose radiation and its effect

    International Nuclear Information System (INIS)

    The title subjects are easily explained. As an introduction, the concept of the ICRP Recommendation (2007) is explained briefly on its use of radiation protection and management. Natural radiation dose to ordinary Japanese is said to be the average 1.5 mSv/y in contrast to the whole world people, 2.4. Medical radiation dose to Japanese is estimated to amount to 2.3 mSv/y, to American, 3.0, and to people of medically advanced nations, 1.92. There are areas always exposed to the natural high dose radiation like Ramsar 10.2 mSv/y (Iran). The effect of such natural low dose has been shown to be all insignificant on cancer mortality in Yangjian area (3.3 mSv/y) in China, on lung cancer risk due to radon in Japan Misasa spa area (>10 mSv/y), and on cancer mortality among 176 thousands nuclear industry workers in Japan (average accumulated dose 12 mSv), etc. There have been such reports as increased bladder cancer in Chernobyl, increased leukemic relative risk of infants whose fathers worked in Sellafield nuclear facility, and acute death/health-injury of residents in the past Lou-Lan area where Chinese nuclear bombs were tested. Fallout data from 1955 to 2011 shows the process of radioactive materials fallen and peaks were due to nuclear tests and Chernobyl/Fukushima Accidents. Basic studies on low dose effect involve those of the radioadoptive response, radiation hormesis, bystander effect and cluster injury of DNA. In low dose-carcinogenesis relationship, presented are models of linear non-threhold (LNT), those estimating lower risk than LNT like linear quadratic (LQ) model, and higher risk like supra-linear model. Risks leading to cancer formation include the occupation and others like medical doctors, tobacco smoking and various anxieties/stresses. (T.T.)

  8. Predicted effects of countermeasures on radiation doses from contaminated food

    International Nuclear Information System (INIS)

    Quantitative assessments of the effects on radiation-dose reductions from nine typical countermeasures against accidental fod contamination have been carried out with dynamic radioecological models. The foodstuffs are assumed to be contaminated with iodine-131, caesium-134 and caesium-137 after a release of radioactive materials from the Ringhals nuclear power station in Sweden resulting from a hypothetical core melt accident. The release of activity of these radionuclides is assumed at 0.07% of the core inventory of the unit 1 reactor (1600 TBq of I-131, 220 TBq of Cs-134 and 190 TBq of Cs-137). Radiation doses are estimated for the 55,000 affected inhabitants along the south-eastern coast of Sweden eating locally produced foodstuffs. The average effective dose equivalent to an individual in the critical group is predicted to be 2.9 mSv from food consumption contaminated with I-131. An accident occurring during winter is estimated to cause average individual doses of 0.32 mSv from Cs-134 and 0.47 mSv from Cs-137, and 9.4 mSv and 6.8 mSv from Cs-134 and Cs-137, respectively, for an accident occurring during summer. Doses from the intake of radioiodine may be reduced by up to a factor of 60 by rejecting contaminated food for 30 days. For the doses from radiocaesium, the largest effect is found form deep ploughing which may reduce the dose by up to a factor of 80. (au) (12 tabs., 6 ills., 19 refs.)

  9. Effect of low dose ionizing radiation upon concentration of

    Energy Technology Data Exchange (ETDEWEB)

    Viliae, M.; Kraljeviae, P.; Simpraga, M.; Miljaniae, S.

    2004-07-01

    It is known that low dose ionizing radiation might have stimulating effects (Luckey, 1982, Kraljeviae, 1988). This fact has also been confirmed in the previous papers of Kraljeviae et al. (2000-2000a; 2001). Namely, those authors showed that irradiation of chicken eggs before incubation by a low dose of 0.15 Gy gamma radiation increases the activity aspartateaminotrasferases (AST) and alanine-aminotransferases (ALT) in blood plasma of chickens hatched from irradiated eggs, as well as growth of chickens during the fattening period. Low doses might also cause changes in the concentration of some biochemical parameters in blood plasma of the same chickens such as changes in the concentration of total proteins, glucose and cholesterol. In this paper, an attempt was made to investigate the effects of low dose gamma radiation upon the concentration of sodium and potassium in the blood plasma of chickens which were hatched from eggs irradiated on the 19th day of incubation by dose of 0.15 Gy. Obtained results were compared with the results from the control group (chickens hatched from nonirradiated eggs). After hatching, all other conditions were the same for both groups. Blood samples were drawn from heart, and later from the wing vein on days 1, 3, 5, 7, 10, 20, 30 and 42. The concentration of sodium and potassium was determined spectrophotometrically by atomic absorbing spectrophotometer Perkin-Elmer 1100B. The concentration of sodium and potassium in blood plasma of chickens hatched from eggs irradiated on the 19th day of incubation by dose of 0.15 Gy indicated a statistically significant increase (P>0.01) only on the first day of the experiment. Obtained results showed that irradiation of eggs on the 19th day of incubation by dose of 0.15 Gy gamma radiation could have effects upon the metabolism of electrolytes in chickens. (Author)

  10. Effective UV radiation dose in polyethylene exposed to weather

    Science.gov (United States)

    González-Mota, R.; Soto-Bernal, J. J.; Rosales-Candelas, I.; Calero Marín, S. P.; Vega-Durán, J. T.; Moreno-Virgen, R.

    2009-09-01

    In this work we quantified the effective UV radiation dose in orange and colorless polyethylene samples exposed to weather in the city of Aguascalientes, Ags. Mexico. The spectral distribution of solar radiation was calculated using SMART 2.9.5.; the samples absorption properties were measured using UV-Vis spectroscopy and the quantum yield was calculated using samples reflectance properties. The determining factor in the effective UV dose is the spectral distribution of solar radiation, although the chemical structure of materials is also important.

  11. Pulsed total dose damage effect experimental study on EPROM

    International Nuclear Information System (INIS)

    Nowadays, memory radiation effect study mainly focus on functionality measurement. Measurable parameters is few in china. According to the present situation, threshold voltage testing method was presented on floating gate EPROM memory. Experimental study of pulsed total dose effect on EPROM threshold voltage was carried out. Damage mechanism was analysed The experiment results showed that memory cell threshold voltage negative shift was caused by pulsed total dose, memory cell threshold voltage shift is basically coincident under steady bias supply and no bias supply. (authors)

  12. Imprecision in predicted dose from 137Cs resulting from biological variability

    International Nuclear Information System (INIS)

    The variability of observed values of human metabolic and physiological characteristics which influence estimates of dose from ingestion of a unit of Cesium-137 activity, and the subsequent predicted total-body dose commitment is analyzed. The analysis is based on extensive literature review and statistical comparison of parameter variability, correlation and reliability

  13. Effective dose to patient during cardiac interventional procedures (Prague workplaces)

    International Nuclear Information System (INIS)

    The aim of this study was to assess effective dose to a patient during cardiac procedures, such as coronary angiography (CA) and percutaneous transluminal angioplasty (PTCA). Measurements were performed on 185 patients in four catheterisation laboratories in three hospitals in Prague using the dose area product (DAP) meter. Calculations of surface and effective dose were performed with Monte-Carlo-based program PCXMC. The mean DAP value per procedure determined in all workplaces ranged between 25.0 and 54.5 Gy cm2 for CA and 43.0-104.5 Gy cm2 for PTCA. In three cases, the surface dose exceeded the 2 Gy level for occurrence of transient erythema. The mean effective dose per procedure in an workplaces was determined to be in the range of 2.7-8.8 mSv for CA and 5.7-15.3 mSv for CA + PTCA combined. The results presented are comparable with those published by other authors. (authors)

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-06-15

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

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

    International Nuclear Information System (INIS)

    To determine the biological effects of low-dose-rate radiation (137Cs, 2.95 mGy/h) on EL4 lymphoma cells during 24 h, we investigated the expression of genes related to apoptosis, cell cycle arrest, DNA repair, iron transport, and ribonucleotide reductase. EL4 cells were continuously exposed to low-dose-rate radiation (total dose: 70.8 mGy) for 24 h. We analyzed cell proliferation and apoptosis by trypan blue exclusion and flow cytometry, gene expression by real-time PCR, and protein levels with the apoptosis ELISA kit. Apoptosis increased in the Low-dose-rate irradiated cells, but cell number did not differ between non- (Non-IR) and Low-dose-rate irradiated (LDR-IR) cells. In concordance with apoptotic rate, the transcriptional activity of ATM, p53, p21, and Parp was upregulated in the LDR-IR cells. Similarly, Phospho-p53 (Ser15), cleaved caspase 3 (Asp175),