Low-Dose Risk, Decisions, and Risk Communication

International Nuclear Information System (INIS)

Flynn, James; Slovic, Paul

2001-01-01

To conduct basic research on how people receive, evaluate, and form positions on scientific information and its relationship to low-dose radiation exposure. There are three major areas of study in our research program. First is the development of theories, frameworks and concepts essential to guiding data collection and analysis. The second area is a program of experimental studies on risk perception, evaluation of science information, and the structure of individual positions regarding low dose exposures. This involves the study of existing knowledge and the evaluation of science information presented within a variety of formats, as educational information, news media stories, and alternative communication methods (personal contact, small group interaction, email and internet, etc.). Third is the community-level studies to examine and record how the social conditions, under which science communications take place, influence the development of attitudes and opinions about: low- dose exposures, the available management options, control of radiation risks, and preferences for program and policy goals

Mutation frequencies in male mice and the estimation of genetic hazards of radiation in men: (specific-locus mutations/dose-rate effect/doubling dose/risk estimation)

International Nuclear Information System (INIS)

Russell, W.L.; Kelly, E.M.

1982-01-01

Estimation of the genetic hazards of ionizing radiation in men is based largely on the frequency of transmitted specific-locus mutations induced in mouse spermatogonial stem cells at low radiation dose rates. The publication of new data on this subject has permitted a fresh review of all the information available. The data continue to show no discrepancy from the interpretation that, although mutation frequency decreases markedly as dose rate is decreased from 90 to 0.8 R/min (1 R = 2.6 X 10 -4 coulombs/kg) there seems to be no further change below 0.8 R/min over the range from that dose rate to 0.0007 R/min. Simple mathematical models are used to compute: (a) a maximum likelihood estimate of the induced mutation frequency at the low dose rates, and (b) a maximum likelihood estimate of the ratio of this to the mutation frequency at high dose rates in the range of 72 to 90 R/min. In the application of these results to the estimation of genetic hazards of radiation in man, the former value can be used to calculate a doubling dose - i.e., the dose of radiation that induces a mutation frequency equal to the spontaneous frequency. The doubling dose based on the low-dose-rate data compiled here is 110 R. The ratio of the mutation frequency at low dose rate to that at high dose rate is useful when it becomes necessary to extrapolate from experimental determinations, or from human data, at high dose rates to the expected risk at low dose rates. The ratio derived from the present analysis is 0.33

Revision of risk estimates and implications for dose limits

International Nuclear Information System (INIS)

Clarke, R.H.

1989-01-01

It has been apparent for some time that our estimates of the risks associated with exposure to ionizing radiation must be increased above those values reported by UNSCEAR in 1977 an dused by ICRP to form their present recommendations. NRPB foresaw some of these changes and introduced interim advice within the UK to restrict exposures of wordkers and members of the public to levels below the existing limits. Since that advice was given, UNSCEAR has produced a 1988 report reviewing human data to provide new estimates of risks associated with exposure at high doses and high doserates. These risk figures are up to 4 times higher than when UNSCEAR reported in 1977. In this paper, the reasons for the changes in the estimates of risk will be described and the current NRPB guidelines for risk factors for protection purposes will be presented. The implications of these new risk factors for the setting of dose limits will then be discussed. (Author). 10 refs.; 2 tabs

Total Risk Management for Low Dose Radiation Exposures

International Nuclear Information System (INIS)

Simic, Z.; Mikulicic, V.; Sterc, D.

2012-01-01

Our civilization is witnessing about century of nuclear age mixed with enormous promises and cataclysmic threats. Nuclear energy seems to encapsulate both potential for pure good and evil or at least we humans are able to perceive that. These images are continuously with us and they are both helping and distracting from making best of nuclear potentials for civilization. Today with nuclear use significantly present and with huge potential to further improve our life with energy and medical use it is of enormous importance to try to have calmed, rational, and objective view on potential risks and certain benefits. Because all use of nuclear energy proved that their immediate risks are negligible (i.e., Three Mile Island and Fukushima) or much smaller than from the other alternatives (i.e., Chernobyl) it seems that the most important issue is the amount of risk from the long term effects to people from exposure to small doses of radiation. A similar issue is present in the increased use of modern computational tomography and other radiation sources use in medicine for examination and therapy. Finally, extreme natural exposures are third such potential risk sources. Definition of low doses varies depending on the way of delivery (i.e., single, multiple or continuous exposures), and for this paper usual dose of 100 mSv is selected as yearly upper amount. There are three very different scientifically supported views on the potential risks from the low doses exposure. The most conservative theory is that all radiation is harmful, and even small increments from background levels (i.e., 2-3 mSv) present additional risk. This view is called linear no threshold theory (LNT) and it is accepted as a regulatory conservative simple approach which guarantees safety. Risk is derived from the extrapolation of the measured effects of high levels of radiation. Opposite theory to LNT is hormesis which assumes that in fact small doses of radiation are helpful and they are improving our

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

International Nuclear Information System (INIS)

Jacob, P

2006-01-01

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

Radiation risk estimation

International Nuclear Information System (INIS)

Schull, W.J.; Texas Univ., Houston, TX

1992-01-01

Estimation of the risk of cancer following exposure to ionizing radiation remains largely empirical, and models used to adduce risk incorporate few, if any, of the advances in molecular biology of a past decade or so. These facts compromise the estimation risk where the epidemiological data are weakest, namely, at low doses and dose rates. Without a better understanding of the molecular and cellular events ionizing radiation initiates or promotes, it seems unlikely that this situation will improve. Nor will the situation improve without further attention to the identification and quantitative estimation of the effects of those host and environmental factors that enhance or attenuate risk. (author)

Risk of radiation-induced cancer at low doses and low dose rates for radiation protection purposes

International Nuclear Information System (INIS)

1995-01-01

The aim of this report is to provide an updated, comprehensive review of the data available for assessing the risk of radiation-induced cancer for radiation protection purposes. Particular emphasis is placed on assessing risks at low doses and low dose rates. The review brings together the results of epidemiological investigations and fundamental studies on the molecular and cellular mechanisms involved in radiation damage. Additionally, this information is supplemented by studies with experimental animals which provide further guidance on the form of the dose-response relationship for cancer induction, as well as on the effect of dose rate on the tumour yield. The emphasis of the report is on cancer induction resulting from exposure to radiations with a low linear energy transfer (LET). The work was performed under contract for the Institut de Protection et de Surete Nucleaire, Fontenay-aux-Roses, Paris, France, whose agreement to publish is gratefully ackowledged. It extends the advice on radiation risks given in Documents of the NRPB, 4 No. 4 (1993). (Author)

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

International Nuclear Information System (INIS)

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

1976-01-01

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

Mammography-oncogenecity at low doses

International Nuclear Information System (INIS)

Heyes, G J; Mill, A J; Charles, M W

2009-01-01

Controversy exists regarding the biological effectiveness of low energy x-rays used for mammography breast screening. Recent radiobiology studies have provided compelling evidence that these low energy x-rays may be 4.42 ± 2.02 times more effective in causing mutational damage than higher energy x-rays. These data include a study involving in vitro irradiation of a human cell line using a mammography x-ray source and a high energy source which matches the spectrum of radiation observed in survivors from the Hiroshima atomic bomb. Current radiation risk estimates rely heavily on data from the atomic bomb survivors, and a direct comparison between the diagnostic energies used in the UK breast screening programme and those used for risk estimates can now be made. Evidence highlighting the increase in relative biological effectiveness (RBE) of mammography x-rays to a range of x-ray energies implies that the risks of radiation-induced breast cancers for mammography x-rays are potentially underestimated by a factor of four. A pooled analysis of three measurements gives a maximal RBE (for malignant transformation of human cells in vitro) of 4.02 ± 0.72 for 29 kVp (peak accelerating voltage) x-rays compared to high energy electrons and higher energy x-rays. For the majority of women in the UK NHS breast screening programme, it is shown that the benefit safely exceeds the risk of possible cancer induction even when this higher biological effectiveness factor is applied. The risk/benefit analysis, however, implies the need for caution for women screened under the age of 50, and particularly for those with a family history (and therefore a likely genetic susceptibility) of breast cancer. In vitro radiobiological data are generally acquired at high doses, and there are different extrapolation mechanisms to the low doses seen clinically. Recent low dose in vitro data have indicated a potential suppressive effect at very low dose rates and doses. Whilst mammography is a low

Risk of cancer subsequent to low-dose radiation

International Nuclear Information System (INIS)

Warren, S.

1980-01-01

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

Estimation of lung tissue doses following exposure to low-LET radiation in the Canadian study of cancer following multiple fluoroscopies

International Nuclear Information System (INIS)

Howe, G.R.; Yaffe, M.

1992-02-01

Lung tissue doses from exposure to external low-LET radiation have been estimated for each year between 1930 and 1960 for 92,707 tuberculosis patients first treated in Canadian institutions between 1930 and 1952. Many of these patients received multiple chest fluoroscopies together with treatment by artificial pneumothorax, and thus accumulated doses up to 15.7 grays. The estimated doses have been used in a statistical analysis of lung cancer mortality between 1950 and 1987 occurring among 64,698 patients known to be alive at the start of 1950, and followed by linkage to the Canadian national mortality data base. There were substantial variations in the total cumulative lung tissue dose received by the cohort, with 2,490 individuals having doses in excess of 1.7 grays. A total of 1,156 lung cancer deaths was observed in the cohort, and these have been used to estimate relative risks. The most appropriate risk model appears to be a simple linear relative risk function, with an excess relative risk coefficient of 0.089 for an absorbed dose of 1 gray. This contrasts with estimates of relative risk based on the atomic bomb survivors study, for which the excess relative risk coefficient for males 20 years after the first exposure is estimated to be 0.64. The difference is statistically significant. It is postulated that fractionation and dose rate effectiveness factors may account for some of the discrepancy. (Modified author abstract) (14 refs., 20 tabs.)

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

Science.gov (United States)

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

2006-01-01

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

Dose dependence on stochastic radiobiological effect in radiation risk estimation

International Nuclear Information System (INIS)

Komochkov, M.M.

1999-01-01

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

The assessment of the carcinogenic effects of low dose radiation

International Nuclear Information System (INIS)

Tubiana, M.; Lafuma, J.; Masse, R.; Latarjet, R.

1991-01-01

It is concluded that the exclusion of patients for the purposes of risk estimation, the choice of a particular relative risk projection model and of a dose reduction factor equal to 2 are all decisions which result in an overestimation of the actual risk. These choices can be understood when the aim is radiation protection and when it is safer to overestimate the risk; however, they are open to criticism if the aim is a realistic assessment of the risk. For low doses, below 50 mSv/year, and when all causes of uncertainty are added, the actual risk might be markedly lower than the risk estimated with the ICRP (1991) carcinogenic risk coefficient and the DRF estimated by ICRP. Future studies should aim at providing direct and more precise assessments of risk coefficients in the low dose region. (Author)

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

International Nuclear Information System (INIS)

Maruyama, Takashi; Nishizawa, Kanae; Kumamoto, Yoshikazu; Iwai, Kazuo; Mase, Naomichi.

1993-01-01

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)

Conformal irradiation of the prostate: estimating long-term rectal bleeding risk using dose-volume histograms

International Nuclear Information System (INIS)

Hartford, Alan C.; Niemierko, Andrzej; Adams, Judith A.; Urie, Marcia M.; Shipley, William U.

1996-01-01

Purpose: Dose-volume histograms (DVHs) may be very useful tools for estimating probability of normal tissue complications (NTCP), but there is not yet an agreed upon method for their analysis. This study introduces a statistical method of aggregating and analyzing primary data from DVHs and associated outcomes. It explores the dose-volume relationship for NTCP of the rectum, using long-term data on rectal wall bleeding following prostatic irradiation. Methods and Materials: Previously published data were reviewed and updated on 41 patients with Stages T3 and T4 prostatic carcinoma treated with photons followed by perineal proton boost, including dose-volume histograms (DVHs) of each patient's anterior rectal wall and data on the occurrence of postirradiation rectal bleeding (minimum FU > 4 years). Logistic regression was used to test whether some individual combination of dose and volume irradiated might best separate the DVHs into categories of high or low risk for rectal bleeding. Further analysis explored whether a group of such dose-volume combinations might be superior in predicting complication risk. These results were compared with results of the 'critical volume model', a mathematical model based on assumptions of underlying radiobiological interactions. Results: Ten of the 128 tested dose-volume combinations proved to be 'statistically significant combinations' (SSCs) distinguishing between bleeders (14 out of 41) and nonbleeders (27 out of 41), ranging contiguously between 60 CGE (Cobalt Gray Equivalent) to 70% of the anterior rectal wall and 75 CGE to 30%. Calculated odds ratios for each SSC were not significantly different across the individual SSCs; however, analysis combining SSCs allowed segregation of DVHs into three risk groups: low, moderate, and high. Estimates of probabilities of normal tissue complications (NTCPs) based on these risk groups correlated strongly with observed data (p = 0.003) and with biomathematical model-generated NTCPs

Risks to health from radiation at low dose rates

International Nuclear Information System (INIS)

Gentner, N.E.; Osborne, R.V.

1997-01-01

Our focus is on whether, using a balance-of-evidence approach, it is possible to say that at a low enough dose, or at a sufficiently low dose rate, radiation risk reduces to zero in a population. We conclude that insufficient evidence exists at present to support such a conclusion. In part this reflects statistical limitations at low doses, and in part (although mechanisms unquestionably exist to protect us against much of the damage induced by ionizing radiation) the biological heterogeneity of human populations, which means these mechanisms do not act in all members of the population at all times. If it is going to be possible to demonstrate that low doses are less dangerous than we presently assume, the evidence, paradoxically, will likely come from studies of higher dose and dose rate scenarios than are encountered occupationally. (author)

Risk at Low Doses: Scientific knowledge, uncertainties and management

International Nuclear Information System (INIS)

Giusssani, A.; Ballarini, F.; Ottolenghi, A.

2002-01-01

Most of the applications of ionizing radiation in the medical field, for the exposed workers as well as the majority of patients undergoing diagnostic examinations, can be seen as low situations. Epidemiological information is however available for dose and dose rates higher than the values typical of most medical situation. Main source of information is the Life Span Study (LSS) of Japanese. A-bomb survivors, supplemented by studies of selected groups of exposed workers (uranium miners, radium painters) or radiotherapy patients with a detailed follow-up history. All of these group studies, however, suffer from one or more of the following limitations: - lack of adequate dosimetry - lack of a reliable control group for the necessary comparison - influence of concomitant factors (not always easy to find out) - influence of social conditions. In addition exposed study populations are different than the population of patients for which the risk estimates are needed in the medical situation. Recent studies aimed to evaluate the available data on the cohorts of the inhabitants of the Techa river settlements as well as of the workers of the Mayak nuclear facilities may provide in the future useful information on large populations chronically exposed to relatively low doses. (Author)

Radiation in space: risk estimates

International Nuclear Information System (INIS)

Fry, R.J.M.

2002-01-01

The complexity of radiation environments in space makes estimation of risks more difficult than for the protection of terrestrial population. In deep space the duration of the mission, position of the solar cycle, number and size of solar particle events (SPE) and the spacecraft shielding are the major determinants of risk. In low-earth orbit missions there are the added factors of altitude and orbital inclination. Different radiation qualities such as protons and heavy ions and secondary radiations inside the spacecraft such as neutrons of various energies, have to be considered. Radiation dose rates in space are low except for short periods during very large SPEs. Risk estimation for space activities is based on the human experience of exposure to gamma rays and to a lesser extent X rays. The doses of protons, heavy ions and neutrons are adjusted to take into account the relative biological effectiveness (RBE) of the different radiation types and thus derive equivalent doses. RBE values and factors to adjust for the effect of dose rate have to be obtained from experimental data. The influence of age and gender on the cancer risk is estimated from the data from atomic bomb survivors. Because of the large number of variables the uncertainties in the probability of the effects are large. Information needed to improve the risk estimates includes: (1) risk of cancer induction by protons, heavy ions and neutrons; (2) influence of dose rate and protraction, particularly on potential tissue effects such as reduced fertility and cataracts; and (3) possible effects of heavy ions on the central nervous system. Risk cannot be eliminated and thus there must be a consensus on what level of risk is acceptable. (author)

Risk estimation and decision making: the health effects on populations of exposure to low levels of ionizing radiation

International Nuclear Information System (INIS)

Fabrikant, J.I.

1982-01-01

Presented is a background for an understanding of the potential health effects in populations exposed to low-level radiation. Discussed is the knowledge about the health effects of low-level radiation. Comments on how the risks of radiation-induced cancer and genetically-related ill-health in man may be estimated, the sources of the scientific and epidemiological data, the dose-response models used, and the uncertainties which limit precise estimates of excess risks from radiation. Also discussed are the implications of numerical risk estimation for radiation protection and decision-making for public health policy

Dose-response characteristics of low- and intermediate-risk prostate cancer treated with external beam radiotherapy

International Nuclear Information System (INIS)

Cheung, Rex; Tucker, Susan L.; Lee, Andrew K.; Crevoisier, Renaud de; Dong Lei; Kamat, Ashish; Pisters, Louis; Kuban, Deborah

2005-01-01

Purpose: In this era of dose escalation, the benefit of higher radiation doses for low-risk prostate cancer remains controversial. For intermediate-risk patients, the data suggest a benefit from higher doses. However, the quantitative characterization of the benefit for these patients is scarce. We investigated the radiation dose-response relation of tumor control probability in low-risk and intermediate-risk prostate cancer patients treated with radiotherapy alone. We also investigated the differences in the dose-response characteristics using the American Society for Therapeutic Radiology and Oncology (ASTRO) definition vs. an alternative biochemical failure definition. Methods and materials: This study included 235 low-risk and 387 intermediate-risk prostate cancer patients treated with external beam radiotherapy without hormonal treatment between 1987 and 1998. The low-risk patients had 1992 American Joint Committee on Cancer Stage T2a or less disease as determined by digital rectal examination, prostate-specific antigen (PSA) levels of ≤10 ng/mL, and biopsy Gleason scores of ≤6. The intermediate-risk patients had one or more of the following: Stage T2b-c, PSA level of ≤20 ng/mL but >10 ng/mL, and/or Gleason score of 7, without any of the following high-risk features: Stage T3 or greater, PSA >20 ng/mL, or Gleason score ≥8. The logistic models were fitted to the data at varying points after treatment, and the dose-response parameters were estimated. We used two biochemical failure definitions. The ASTRO PSA failure was defined as three consecutive PSA rises, with the time to failure backdated to the mid-point between the nadir and the first rise. The second biochemical failure definition used was a PSA rise of ≥2 ng/mL above the current PSA nadir (CN + 2). The failure date was defined as the time at which the event occurred. Local, nodal, and distant relapses and the use of salvage hormonal therapy were also failures. Results: On the basis of the

On possible risks of low-dose irradiation

International Nuclear Information System (INIS)

Hug, O.; Gesellschaft fuer Strahlen- und Umweltforschung m.b.H., Neuherberg/Muenchen

1974-01-01

The survey on more recent experimental and epidemiological data and newer concepts for a realistic estimation of the radiation risk leads to the conclusion that for radiation late damages and possibly also for genetic damages with a chronical radiation exposure in the order of magnitude of the natural radiation exposure and probably also in the order of magnitude of the maximum permissible radiation dose, the risk is very probably lower than is to be expected based on the findings after relatively high doses and dose rates. A few less direct comparative studies have detected a time factor of 3 to 5. Considering the analysis of the RBW demely ionizing radiation which at high doses is not greater than 3, increases with decreasing dose and according to biophysical considerations, can possibly reach a value of 30, an effectiveness reduced by a factor of 10 of small doses and dose rates of loosely ionizing radiation would be even to be expected. All radiobiological knowledge on the effect of ionizing radiation allows one to expect that even smallest radiation doses can cause cellular damages due to the linear irreversable components of the radiation effect and probably that these damages can even be the starting point of a malignant tumour. Regarding this cancer-initiating effect however, the effectiveness of loosely ionizing radiation per rad in the region of natural radiation exposure lie considerably below that existing at high doses and dose rates. Whether however this initial carcinogenic effect of very small doses is at all noticeable during the average life duration in an increase of the spontaneous age-specific tumour rate is questionable if the assumption is confirmed that with decreasing dose, the time manifestation of the radiation induced tumours is delayed. (orig./LH) [de

Cancer risk from low doses of ionizing radiation

Energy Technology Data Exchange (ETDEWEB)

Auvinen, A

1997-06-01

The aim of the study was to estimate cancer risk from small doses of ionizing radiation from various sources, including both external and internal exposure. The types of radiation included alpha, gamma, and neutron radiation. A nationwide follow-up study covering the years up to 1992 revealed no significant association between fallout from the Chernobyl accident and incidence of childhood leukemia. An excess of eight cases or more per year could be excluded. However, some indication of an increase was evident in the most heavily affected areas. Furthermore, the risk estimates were in accordance with those reported from Hiroshima and Nagasaki, although the confidence intervals were wide. (282 refs.).

Cancer risk from low doses of ionizing radiation

International Nuclear Information System (INIS)

Auvinen, A.

1997-06-01

The aim of the study was to estimate cancer risk from small doses of ionizing radiation from various sources, including both external and internal exposure. The types of radiation included alpha, gamma, and neutron radiation. A nationwide follow-up study covering the years up to 1992 revealed no significant association between fallout from the Chernobyl accident and incidence of childhood leukemia. An excess of eight cases or more per year could be excluded. However, some indication of an increase was evident in the most heavily affected areas. Furthermore, the risk estimates were in accordance with those reported from Hiroshima and Nagasaki, although the confidence intervals were wide. (282 refs.)

Estimating doses and risks associated with decontamination and decommissioning activities using the CRRIS

International Nuclear Information System (INIS)

Miller, C.W.; Sjoreen, A.L.; Cotter, S.J.

1986-01-01

The Computerized Radiological Risk Investigation System (CRRIS) is applicable to determining doses and risks from a variety of decontamination and decommissioning activities. For example, concentrations in air from resuspended radionuclides initially deposited on the ground surface and the concentrations of deposited radionuclides in various soil layers can be obtained. The CRRIS will estimate exposure to radon and its progeny in terms of working-level months, and will compute the resulting health risks. The CRRIS consists of seven integrated computer codes that stand alone or are run as a system to calculate environmental transport, doses, and risks. PRIMUS output provides other CRRIS codes the capability to handle radionuclide decay chains. ANEMOS and RETADD-II calculate atmospheric dispersion and deposition for local and regional distances, respectively. Multiple ANEMOS runs for sources within a small area are combined on a master grid by SUMIT. MLSOIL is used to estimate effective ground surface concentrations for dose computations. TERRA calculates food chain transport, and ANDROS calculates individual or population exposures, doses, and risks. Applications of the CRRIS to decontamination problems are discussed. 16 refs., 1 fig

Estimation of radiation exposure from lung cancer screening program with low-dose computed tomography

Energy Technology Data Exchange (ETDEWEB)

Kim, Su Yeon; Jun, Jae Kwan [Graduate School of Cancer Science and Policy, National Cancer Center, Seoul (Korea, Republic of)

2016-12-15

The National Lung Screening Trial (NLST) demonstrated that screening with Low-dose Computed Tomography (LDCT) screening reduced lung cancer mortality in a high-risk population. Recently, the United States Preventive Services Task Force (USPSTF) gave a B recommendation for annual LDCT screening for individuals at high-risk. With the promising results, Korea developed lung cancer screening guideline and is planning a pilot study for implementation of national lung cancer screening. With widespread adoption of lung cancer screening with LDCT, there are concerns about harms of screening, including high false-positive rates and radiation exposure. Over the 3 rounds of screening in the NLST, 96.4% of positive results were false-positives. Although the initial screening is performed at low dose, subsequent diagnostic examinations following positive results additively contribute to patient's lifetime exposure. As with implementing a large-scale screening program, there is a lack of established risk assessment about the effect of radiation exposure from long-term screening program. Thus, the purpose of this study was to estimate cumulative radiation exposure of annual LDCT lung cancer screening program over 20-year period.

Low dose diagnostic radiation does not increase cancer risk in cancer prone mice

Energy Technology Data Exchange (ETDEWEB)

Boreham, D., E-mail: dboreham@nosm.ca [Northern Ontario School of Medicine, ON (Canada); Phan, N., E-mail: nghiphan13@yahoo.com [Univ. of Ottawa, Ottawa, ON (Canada); Lemon, J., E-mail: lemonja@mcmaster.ca [McMaster Univ., Hamilton, ON (Canada)

2014-07-01

The increased exposure of patients to low dose diagnostic ionizing radiation has created concern that these procedures will result in greater risk of carcinogenesis. However, there is substantial evidence that shows in many cases that low dose exposure has the opposite effect. We have investigated whether CT scans can modify mechanisms associated with carcinogenesis in cancer-prone mice. Cancer was induced in Trp53+/- mice with an acute high dose whole-body 4 Gy γ-radiation exposure. Four weeks following the cancer-inducing dose, weekly whole-body CT scans (10 mGy/scan, 75 kVp X-rays) were given for ten consecutive weeks adding an additional radiation burden of 0.1 Gy. Short-term biological responses and subsequent lifetime cancer risk were investigated. Five days following the last CT scan, there were no detectable differences in the spontaneous levels of DNA damage in blood cells (reticulocytes). In fact, CT scanned mice had significantly lower constitutive levels of oxidative DNA damage and cell death (apoptosis), compared to non-CT scanned mice. This shows that multiple low dose radiation exposures modified the radio response and indicates protective processes were induced in mice. In mice treated with the multiple CT scans following the high cancer-inducing 4 Gy dose, tumour latency was increased, significantly prolonging lifespan. We conclude that repeated CT scans can reduce the cancer risk of a prior high-dose radiation exposure, and delay the progression of specific types of radiation-induced cancers in Trp53+/-mice. This research shows for the first time that low dose exposure long after cancer initiation events alter risk and reduce cancer morbidity. Cancer induction following low doses does not follow a linear non-threshold model of risk and this model should not be used to extrapolate risk to humans following low dose exposure to ionizing radiation. (author)

Review of European research trends of low dose radiation risk

International Nuclear Information System (INIS)

Iwasaki, Toshiyasu; Yoshida, Kazuo

2010-01-01

Large research projects on low dose radiation effects in Europe and US over the past decade have provided limited scientific knowledge which could underpin the validation of radiation protection systems. Recently in Europe, there have been repeated discussions and dialogues to improve the situation, and as the consequence, the circumstances surrounding low dose radiation risks are changing. In 2009, Multidisciplinary European Low Dose Initiative (MELODI) was established as a trans-national organization capable of ensuring appropriate governance of research in the pursuit of a long term shared vision, and Low Dose Research towards Multidisciplinary Integration (DoReMi) network was launched in 2010 to achieve fairly short term results in order to prove the validity of the MELODI approach. It is expected to be very effective and powerful activities to facilitate the reduction of uncertainties in the understanding of low dose risks, but the regulatory requests rushing the reinforcement of radiological protection regulations based on the precautional principles are more increasing. To develop reasonable radiological protection systems based on scientific evidences, we need to accelerate to collect scientific evidences which could directly underpin more appropriate radiation protection systems even in Japan. For the purpose, we Japan need to develop from an independent standpoint and share as a multidisciplinary vision a long term and holistic research strategy which enables to enhance Japanese advantages such as low dose rate facilities and animal facilities, as soon as possible. (author)

What can be learned from epidemiologic studies of persons exposed to low doses of radiation?

International Nuclear Information System (INIS)

Gilbert, E.S.

1993-04-01

The main objective of radiation risk assessment is to determine the risk of various adverse health effects associated with exposure to low doses and low dose rates. Extrapolation of risks from studies of persons exposed at high doses (generally exceeding 1 Sv) and dose rates has been the primary approach used to achieve this objective. The study of Japanese atomic bomb survivors in Hiroshima and Nagasaki has played an especially important role in risk assessment efforts. A direct assessment of the dose-response function based on studies of persons exposed at low doses and dose rates is obviously desirable. This paper focuses on the potential of both current and future nuclear workers studies for investigating the dose-response functions at low doses, and also discusses analyses making use of the low dose portion of the atomic bomb survivor data. Difficulties in using these data are the statistical imprecision of estimated dose-response parameters, and potential bias resulting from confounding factors and from uncertainties in dose estimates

Health effect of low dose/low dose rate radiation

International Nuclear Information System (INIS)

Kodama, Seiji

2012-01-01

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

Mechanisms of Enhanced Cell Killing at Low Doses: Implications for Radiation Risk

International Nuclear Information System (INIS)

Johnston, Peter J.; Wilson, George D.

2003-01-01

We have shown that cell lethality actually measured after exposure to low-doses of low-LET radiation, is markedly enhanced relative to the cell lethality previously expected by extrapolation of the high-dose cell-killing response. Net cancer risk is a balance between cell transformation and cell kill and such enhanced lethality may more than compensate for transformation at low radiation doses over a least the first 10 cGy of low-LET exposure. This would lead to a non-linear, threshold, dose-risk relationship. Therefore our data imply the possibility that the adverse effects of small radiation doses (<10 cGy) could be overestimated in specific cases. It is now important to research the mechanisms underlying the phenomenon of low-dose hypersensitivity to cell killing, in order to determine whether this can be generalized to safely allow an increase in radiation exposure limits. This would have major cost-reduction implications for the whole EM program

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

International Nuclear Information System (INIS)

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

2003-01-01

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

Current estimates of radiation risks and implications for dose limits

International Nuclear Information System (INIS)

Clarke, R.H.

1989-01-01

The publication of the 1988 report of UNSCEAR represents a major step forward in that there is an international consensus on the estimation of risk from exposure to ionising radiation. The estimates of fatal cancers in the UNSCEAR report are up to 4 times the values in the 1977 review. This paper will describe the reasons for the increase, the remaining uncertainties and the implications for dose limits in occupational and public exposure. (author)

Estimation of organ doses and risk of cancer associated with CT examination

International Nuclear Information System (INIS)

Ahmed, Nagla Nooraldaim

2017-11-01

The purpose of this study to estimate the organ closes and risk of cancer associated with CT examinations in Khartoum state, where the study conducted in three hospitals; Alzytouna , royal scan and Royal Care. From April to November 2017, and the data collected from 120 patients, 40 patents from each hospital undergoing CT brain and abdomen examinations. The data were entered to CT - Expo version 2.4 software for calculation the effective dose and organ dose and by Xray risk web site for calculate the risk factor associated with CT examinations. Results have shown the values of effective dose that found 9.73 mSv for all patients and for female and male 9.9 mSv respectively. The effective dose from Brain examinations in three hospitals Alzytouna Royal scan and Royal Care was 16.9 mSv, 3.7 mSv, 3.8 mSv respectively, and from abdomen examinations was 4.2 mSv, 7.6 mSv, 22.2 mSv respectively. Comparing te effective dose from the hospitals, for Ct. Brain in Alzytouna hospital was higher than other hospitals; and for CT Abdomen in Royal Care hospital was higher than other hospitals, but still under the risk levels according to the ICRP report. For organ doses results, the most organs exposed from CT. brain was brain, salivary gland, thyroid gland, Bone marrow, Bone surface, Extra thoracic tissue, Eye lens and oral mucosa received ( 70,2, 66.4,15.04, 10.9, 24.9, 14.8,89.5,65.07) mSv respectively. The most organs exposed from CT. Abdomen were liver, stomach, low, Large intestine, Bladder, Bone surface, upper , Large intestine, spleen, kidney, small intestine and prostate received (16.53, 12.8, 33.43, 41.01,20.5, 38.4, 14.7, 28.9, 37.5,30.5 ) mSv respectively. This study found that te ability of cancer induced i the female was higher from the male; dut to body component of the female. (Author)

Estimation of population dose and risk to holding assistants from veterinary X-ray examination in Japan

International Nuclear Information System (INIS)

Hashizume, Tadashi; Suganuma, Tunenori; Shida, Takuo

1989-01-01

For the estimation of the population doses and risks of stochastic effects to assistants who hold animals during veterinary X-ray examination, a random survey of hospitals and clinics was carried out concerning age distribution of such assistants by groups of facilities. The average organ and tissue dose per examination was evaluated from the experimental data using mean technical factors such as X-ray tube voltage, tube current and field size based on the results of a nationwide survey. The population doses to the assistants were calculated to be about 14 nSv per person per year for the genetically significant dose, 3.5 nSv per person per year for per caput mean marrow dose, 3.3 nSv for the leukemia significant dose and 4.5 nSv for the malignant significant dose, respectively. The total risk of stochastic effects to the Japanese population from holding assistants was estimated using population data and it was estimated to be less than one person per year, but the cancer risks to a number of the assistants were estimated to be more than 4 x 10 -5 . (author)

Estimates of Health Detriments and Tissue Weighting Factors for Hong Kong Populations from Low Dose, Low Dose Rate and Low LET Ionising Radiation Exposure

International Nuclear Information System (INIS)

Lee, S.K.

1998-01-01

The total health detriments and the tissue weighting factors for the Hong Kong populations from low dose, low dose rate and low LET ionising radiation exposure are obtained according to the methodology recommended in ICRP Publication 60. The probabilities of fatal cancers for the general (ages 0-90) and working (ages 20-64) populations due to lifetime exposure at low dose and low dose rate are 4.9 x 10 -2 Sv -1 and 3.6 x 10 -2 Sv -1 respectively, comparing with the ICRP 60 estimates of 5.0 x 10 -2 Sv -1 and 4.0 x 10 -2 Sv -1 . The corresponding total health detriments for the general and working populations are 6.9 x 10 -2 Sv -1 and 4.9 x 10 -2 Sv -1 respectively comparing with the ICRP 60 estimates of 7.3 x 10 -2 Sv -1 and 5.6 x 10 -2 Sv -1 . Tissue weighting factors for the general population are 0.01 (bone surface and skin), 0.02 (liver, oesophagus and thyroid), 0.04 (bladder and breast), 0.08 (remainder), 0.10 (stomach), 0.11 (bone marrow), 0.15 (colon), 0.19 (lung) and 0.21 (gonads) and for the working population are 0.01 (bone surface and skin), 0.03 (liver, oesophagus and thyroid), 0.04 (breast), 0.06 (remainder), 0.07 (bladder), 0.08 (colon), 0.14 (bone marrow and stomach), 0.16 (lung) and 0.20 (gonads). (author)

Radiation dose and cancer risk estimates in helical CT for pulmonary tuberculosis infections

Directory of Open Access Journals (Sweden)

Adeleye Bamise

2017-12-01

Full Text Available The preference for computed tomography (CT for the clinical assessment of pulmonary tuberculosis (PTB infections has increased the concern about the potential risk of cancer in exposed patients. In this study, we investigated the correlation between cancer risk and radiation doses from different CT scanners, assuming an equivalent scan protocol. Radiation doses from three 16-slice units were estimated using the CT-Expo dosimetry software version 2.4 and standard CT scan protocol for patients with suspected PTB infections. The lifetime risk of cancer for each scanner was determined using the methodology outlined in the BEIR VII report. Organ doses were significantly different (P < 0.05 between the scanners. The calculated effective dose for scanner H2 is 34% and 37% higher than scanners H3 and H1 respectively. A high and statistically significant correlation was observed between estimated lifetime cancer risk for both male (r2 = 0.943, P < 0.05 and female patients (r2 = 0.989, P < 0.05. The risk variation between the scanners was slightly higher than 2% for all ages but was much smaller for specific ages for male and female patients (0.2% and 0.7%, respectively. These variations provide an indication that the use of a scanner optimizing protocol is imperative.

Radiation dose and cancer risk estimates in helical CT for pulmonary tuberculosis infections

Science.gov (United States)

Adeleye, Bamise; Chetty, Naven

2017-12-01

The preference for computed tomography (CT) for the clinical assessment of pulmonary tuberculosis (PTB) infections has increased the concern about the potential risk of cancer in exposed patients. In this study, we investigated the correlation between cancer risk and radiation doses from different CT scanners, assuming an equivalent scan protocol. Radiation doses from three 16-slice units were estimated using the CT-Expo dosimetry software version 2.4 and standard CT scan protocol for patients with suspected PTB infections. The lifetime risk of cancer for each scanner was determined using the methodology outlined in the BEIR VII report. Organ doses were significantly different (P < 0.05) between the scanners. The calculated effective dose for scanner H2 is 34% and 37% higher than scanners H3 and H1 respectively. A high and statistically significant correlation was observed between estimated lifetime cancer risk for both male (r2 = 0.943, P < 0.05) and female patients (r2 = 0.989, P < 0.05). The risk variation between the scanners was slightly higher than 2% for all ages but was much smaller for specific ages for male and female patients (0.2% and 0.7%, respectively). These variations provide an indication that the use of a scanner optimizing protocol is imperative.

TU-C-18A-01: Models of Risk From Low-Dose Radiation Exposures: What Does the Evidence Say?

International Nuclear Information System (INIS)

Bushberg, J; Boreham, D; Ulsh, B

2014-01-01

At dose levels of (approximately) 500 mSv or more, increased cancer incidence and mortality have been clearly demonstrated. However, at the low doses of radiation used in medical imaging, the relationship between dose and cancer risk is not well established. As such, assumptions about the shape of the dose-response curve are made. These assumptions, or risk models, are used to estimate potential long term effects. Common models include 1) the linear non-threshold (LNT) model, 2) threshold models with either a linear or curvilinear dose response above the threshold, and 3) a hormetic model, where the risk is initially decreased below background levels before increasing. The choice of model used when making radiation risk or protection calculations and decisions can have significant implications on public policy and health care decisions. However, the ongoing debate about which risk model best describes the dose-response relationship at low doses of radiation makes informed decision making difficult. This symposium will review the two fundamental approaches to determining the risk associated with low doses of ionizing radiation, namely radiation epidemiology and radiation biology. The strengths and limitations of each approach will be reviewed, the results of recent studies presented, and the appropriateness of different risk models for various real world scenarios discussed. Examples of well-designed and poorly-designed studies will be provided to assist medical physicists in 1) critically evaluating publications in the field and 2) communicating accurate information to medical professionals, patients, and members of the general public. Equipped with the best information that radiation epidemiology and radiation biology can currently provide, and an understanding of the limitations of such information, individuals and organizations will be able to make more informed decisions regarding questions such as 1) how much shielding to install at medical facilities, 2) at

TU-C-18A-01: Models of Risk From Low-Dose Radiation Exposures: What Does the Evidence Say?

Energy Technology Data Exchange (ETDEWEB)

Bushberg, J [UC Davis Medical Center, Sacramento, CA (United States); Boreham, D [McMaster University, Ontario, CA (Canada); Ulsh, B

2014-06-15

At dose levels of (approximately) 500 mSv or more, increased cancer incidence and mortality have been clearly demonstrated. However, at the low doses of radiation used in medical imaging, the relationship between dose and cancer risk is not well established. As such, assumptions about the shape of the dose-response curve are made. These assumptions, or risk models, are used to estimate potential long term effects. Common models include 1) the linear non-threshold (LNT) model, 2) threshold models with either a linear or curvilinear dose response above the threshold, and 3) a hormetic model, where the risk is initially decreased below background levels before increasing. The choice of model used when making radiation risk or protection calculations and decisions can have significant implications on public policy and health care decisions. However, the ongoing debate about which risk model best describes the dose-response relationship at low doses of radiation makes informed decision making difficult. This symposium will review the two fundamental approaches to determining the risk associated with low doses of ionizing radiation, namely radiation epidemiology and radiation biology. The strengths and limitations of each approach will be reviewed, the results of recent studies presented, and the appropriateness of different risk models for various real world scenarios discussed. Examples of well-designed and poorly-designed studies will be provided to assist medical physicists in 1) critically evaluating publications in the field and 2) communicating accurate information to medical professionals, patients, and members of the general public. Equipped with the best information that radiation epidemiology and radiation biology can currently provide, and an understanding of the limitations of such information, individuals and organizations will be able to make more informed decisions regarding questions such as 1) how much shielding to install at medical facilities, 2) at

Risk estimates for the health effects of alpha radiation

International Nuclear Information System (INIS)

Thomas, D.C.; McNeill, K.G.

1981-09-01

This report provides risk estimates for various health effects of alpha radiation. Human and animal data have been used to characterize the shapes of dose-response relations and the effects of various modifying factors, but quantitative risk estimates are based solely on human data: for lung cancer, on miners in the Colorado plateau, Czechoslovakia, Sweden, Ontario and Newfoundland; for bone and head cancers, on radium dial painters and radium-injected patients. Slopes of dose-response relations for lung cancer show a tendency to decrease with increasing dose. Linear extrapolation is unlikely to underestimate the excess risk at low doses by more than a factor of l.5. Under the linear cell-killing model, our best estimate

Estimation of effective dose and lifetime attributable risk from multiple head CT scans in ventriculoperitoneal shunted children

International Nuclear Information System (INIS)

Aw-Zoretic, J.; Seth, D.; Katzman, G.; Sammet, S.

2014-01-01

Purpose: The purpose of this review is to determine the averaged effective dose and lifetime attributable risk factor from multiple head computed tomography (CT) dose data on children with ventriculoperitoneal shunts (VPS). Method and materials: A total of 422 paediatric head CT exams were found between October 2008 and January 2011 and retrospectively reviewed. The CT dose data was weighted with the latest IRCP 103 conversion factor to obtain the effective dose per study and the averaged effective dose was calculated. Estimates of the lifetime attributable risk were also calculated from the averaged effective dose using a conversion factor from the latest BEIR VII report. Results: Our study found the highest effective doses in neonates and the lowest effective doses were observed in the 10–18 years age group. We estimated a 0.007% potential increase risk in neonates and 0.001% potential increased risk in teenagers over the base risk. Conclusion: Multiple head CTs in children equates to a slight potential increase risk in lifetime attributable risk over the baseline risk for cancer, slightly higher in neonates relative to teenagers. The potential risks versus clinical benefit must be assessed

TU-H-207A-08: Estimating Radiation Dose From Low-Dose Lung Cancer Screening CT Exams Using Tube Current Modulation

International Nuclear Information System (INIS)

Hardy, A; Bostani, M; McMillan, K; Zankl, M; Cagnon, C; McNitt-Gray, M

2016-01-01

Purpose: The purpose of this work is to estimate effective and lung doses from a low-dose lung cancer screening CT protocol using Tube Current Modulation (TCM) across patient models of different sizes. Methods: Monte Carlo simulation methods were used to estimate effective and lung doses from a low-dose lung cancer screening protocol for a 64-slice CT (Sensation 64, Siemens Healthcare) that used TCM. Scanning parameters were from the AAPM protocols. Ten GSF voxelized patient models were used and had all radiosensitive organs identified to facilitate estimating both organ and effective doses. Predicted TCM schemes for each patient model were generated using a validated method wherein tissue attenuation characteristics and scanner limitations were used to determine the TCM output as a function of table position and source angle. The water equivalent diameter (WED) was determined by estimating the attenuation at the center of the scan volume for each patient model. Monte Carlo simulations were performed using the unique TCM scheme for each patient model. Lung doses were tallied and effective doses were estimated using ICRP 103 tissue weighting factors. Effective and lung dose values were normalized by scanspecific 32 cm CTDIvol values based upon the average tube current across the entire simulated scan. Absolute and normalized doses were reported as a function of WED for each patient. Results: For all ten patients modeled, the effective dose using TCM protocols was below 1.5 mSv. Smaller sized patient models experienced lower absolute doses compared to larger sized patients. Normalized effective and lung doses showed some dependence on patient size (R2 = 0.77 and 0.78, respectively). Conclusion: Effective doses for a low-dose lung screening protocol using TCM were below 1.5 mSv for all patient models used in this study. Institutional research agreement, Siemens Healthcare; Past recipient, research grant support, Siemens Healthcare; Consultant, Toshiba America Medical

TU-H-207A-08: Estimating Radiation Dose From Low-Dose Lung Cancer Screening CT Exams Using Tube Current Modulation

Energy Technology Data Exchange (ETDEWEB)

Hardy, A; Bostani, M [University of California, Los Angeles, Los Angeles, CA (United States); McMillan, K [Mayo Clinic, Rochester, MN (United States); Zankl, M [Helmholtz Zentrum Munchen, Neuherberg (Germany); Cagnon, C [UCLA Medical Center, Los Angeles, CA (United States); McNitt-Gray, M [UCLA School of Medicine, Los Angeles, CA (United States)

2016-06-15

Purpose: The purpose of this work is to estimate effective and lung doses from a low-dose lung cancer screening CT protocol using Tube Current Modulation (TCM) across patient models of different sizes. Methods: Monte Carlo simulation methods were used to estimate effective and lung doses from a low-dose lung cancer screening protocol for a 64-slice CT (Sensation 64, Siemens Healthcare) that used TCM. Scanning parameters were from the AAPM protocols. Ten GSF voxelized patient models were used and had all radiosensitive organs identified to facilitate estimating both organ and effective doses. Predicted TCM schemes for each patient model were generated using a validated method wherein tissue attenuation characteristics and scanner limitations were used to determine the TCM output as a function of table position and source angle. The water equivalent diameter (WED) was determined by estimating the attenuation at the center of the scan volume for each patient model. Monte Carlo simulations were performed using the unique TCM scheme for each patient model. Lung doses were tallied and effective doses were estimated using ICRP 103 tissue weighting factors. Effective and lung dose values were normalized by scanspecific 32 cm CTDIvol values based upon the average tube current across the entire simulated scan. Absolute and normalized doses were reported as a function of WED for each patient. Results: For all ten patients modeled, the effective dose using TCM protocols was below 1.5 mSv. Smaller sized patient models experienced lower absolute doses compared to larger sized patients. Normalized effective and lung doses showed some dependence on patient size (R2 = 0.77 and 0.78, respectively). Conclusion: Effective doses for a low-dose lung screening protocol using TCM were below 1.5 mSv for all patient models used in this study. Institutional research agreement, Siemens Healthcare; Past recipient, research grant support, Siemens Healthcare; Consultant, Toshiba America Medical

Randomized phase 2 study of low-dose decitabine vs low-dose azacitidine in lower-risk MDS and MDS/MPN.

Science.gov (United States)

Jabbour, Elias; Short, Nicholas J; Montalban-Bravo, Guillermo; Huang, Xuelin; Bueso-Ramos, Carlos; Qiao, Wei; Yang, Hui; Zhao, Chong; Kadia, Tapan; Borthakur, Gautam; Pemmaraju, Naveen; Sasaki, Koji; Estrov, Zeev; Cortes, Jorge; Ravandi, Farhad; Alvarado, Yesid; Komrokji, Rami; Sekeres, Mikkael A; Steensma, David P; DeZern, Amy; Roboz, Gail; Kantarjian, Hagop; Garcia-Manero, Guillermo

2017-09-28

Hypomethylating agents (HMAs) improve survival in patients with higher-risk myelodysplastic syndromes (MDS) but are less well-studied in lower-risk disease. We compared the safety and efficacy of low-dose decitabine vs low-dose azacitidine in this group of patients. Adults with low- or intermediate 1-risk MDS or MDS/myeloproliferative neoplasm (MPN), including chronic myelomonocytic leukemia, according to the International Prognostic Scoring System, were randomly assigned using a Bayesian adaptive design to receive either azacitidine 75 mg/m 2 intravenously/subcutaneously daily or decitabine 20 mg/m 2 intravenously daily for 3 consecutive days on a 28-day cycle. The primary outcome was overall response rate (ORR). Between November 2012 and February 2016, 113 patients were treated: 40 (35%) with azacitidine and 73 (65%) with decitabine. The median age was 70 years; 81% of patients were intermediate 1-risk patients. The median number of cycles received was 9. The ORRs were 70% and 49% ( P = .03) for patients treated with decitabine and azacitidine, respectively. Thirty-two percent of patients treated with decitabine became transfusion independent compared with 16% of patients treated with azacitidine ( P = .2). Cytogenetic response rates were 61% and 25% ( P = .02), respectively. With a median follow-up of 20 months, the overall median event-free survival was 18 months: 20 and 13 months for patients treated with decitabine and azacitidine, respectively ( P = .1). Treatment was well tolerated, with a 6-week mortality rate of 0%. The use of low-dose HMAs is safe and effective in patients with lower-risk MDS and MDS/MPN. Their effect on the natural history of lower-risk disease needs to be further studied. This trial was registered at clinicaltrials.gov (identifier NCT01720225). © 2017 by The American Society of Hematology.

Patient-specific radiation dose and cancer risk estimation in CT: Part II. Application to patients

Energy Technology Data Exchange (ETDEWEB)

Li Xiang; Samei, Ehsan; Segars, W. Paul; Sturgeon, Gregory M.; Colsher, James G.; Toncheva, Greta; Yoshizumi, Terry T.; Frush, Donald P. [Medical Physics Graduate Program, Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Duke University Medical Center, Durham, North Carolina 27705 (United States); Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Medical Physics Graduate Program, Department of Physics, and Department of Biomedical Engineering, Duke University Medical Center, Durham, North Carolina 27705 (United States); Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Medical Physics Graduate Program, Duke University Medical Center, Durham, North Carolina 27705 (United States); Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Duke University Medical Center, Durham, North Carolina 27705 and Department of Biomedical Engineering, University of North Carolina, Chapel Hill, North Carolina 27599 (United States); Department of Radiology, Duke University Medical Center, Durham, North Carolina 27705 (United States); Duke Radiation Dosimetry Laboratory, Department of Radiology, Duke University Medical Center, Durham, North Carolina 27705 (United States); Duke Radiation Dosimetry Laboratory, Department of Radiology, Medical Physics Graduate Program, Duke University Medical Center, Durham, North Carolina 27705 (United States); Division of Pediatric Radiology, Department of Radiology, Medical Physics Graduate Program, Duke University Medical Center, Durham, North Carolina 27710 (United States)

2011-01-15

Purpose: Current methods for estimating and reporting radiation dose from CT examinations are largely patient-generic; the body size and hence dose variation from patient to patient is not reflected. Furthermore, the current protocol designs rely on dose as a surrogate for the risk of cancer incidence, neglecting the strong dependence of risk on age and gender. The purpose of this study was to develop a method for estimating patient-specific radiation dose and cancer risk from CT examinations. Methods: The study included two patients (a 5-week-old female patient and a 12-year-old male patient), who underwent 64-slice CT examinations (LightSpeed VCT, GE Healthcare) of the chest, abdomen, and pelvis at our institution in 2006. For each patient, a nonuniform rational B-spine (NURBS) based full-body computer model was created based on the patient's clinical CT data. Large organs and structures inside the image volume were individually segmented and modeled. Other organs were created by transforming an existing adult male or female full-body computer model (developed from visible human data) to match the framework defined by the segmented organs, referencing the organ volume and anthropometry data in ICRP Publication 89. A Monte Carlo program previously developed and validated for dose simulation on the LightSpeed VCT scanner was used to estimate patient-specific organ dose, from which effective dose and risks of cancer incidence were derived. Patient-specific organ dose and effective dose were compared with patient-generic CT dose quantities in current clinical use: the volume-weighted CT dose index (CTDI{sub vol}) and the effective dose derived from the dose-length product (DLP). Results: The effective dose for the CT examination of the newborn patient (5.7 mSv) was higher but comparable to that for the CT examination of the teenager patient (4.9 mSv) due to the size-based clinical CT protocols at our institution, which employ lower scan techniques for smaller

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

International Nuclear Information System (INIS)

Thomas, J.M.; Eberhardt, L.L.

1981-01-01

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

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

International Nuclear Information System (INIS)

Thomas, J.M.; Eberhardt, L.L.

1981-01-01

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

The carcinogenic risks of low-LET and high-LET ionizing radiations

International Nuclear Information System (INIS)

Fabrikant, J.I.

1991-08-01

This report presents a discussion on risk from ionizing radiations to human populations. Important new information on human beings has come mainly from further follow-up of existing epidemiological studies, notably the Japanese atomic bomb survivors and the ankylosing spondylitis patients; from new epidemiological surveys, such as the patients treated for cancer of the uterine cervix; and from combined surveys, including workers exposed in underground mines. Since the numerous and complex differences among the different study populations introduce factors that influence the risk estimates derived in ways that are not completely understood, it is not clear how to combine the different risk estimates obtained. These factors involve complex biological and physical variables distributed over time. Because such carcinogenic effects occur too infrequently to be demonstrated at low doses, the risks of low-dose radiation can be estimated only by interpolation from observations at high doses on the basis of theoretical concepts, mathematical models and available empirical evidence, primarily the epidemiological surveys of large populations exposed to ionizing radiation. In spite of a considerable amount of research, only recently has there has been efforts to apply the extensive laboratory data in animals to define the dose-incidence relationship in the low dose region. There simply are insufficient data in the epidemiological studies of large human populations to estimate risk coefficients directly from exposure to low doses. The risk estimates for the carcinogenic effects of radiation have been, in the past, somewhat low and reassessment of the numerical values is now necessary

Studies of workers exposed to low doses of external radiation

International Nuclear Information System (INIS)

Gilbert, E.S.

1991-04-01

Currently, several epidemiologic studies of workers who have been exposed occupationally to low levels of radiation are being conducted, and include studies of workers in the United States, Great Britain, and Canada involved in the production of both defense materials and nuclear power. This paper focuses on studies that evaluate the possible adverse effects resulting from external exposure to radiation. The radiation risk estimates that have been used to establish radiation protection standards for workers and others have been obtained mainly from studies of persons exposed at high doses and dose rates. However, questions remain with regard to the extrapolation process that has been necessary for estimating low-level radiation risks. Occupational studies provide a direct assessment of risk based on data on persons exposed at the actual levels of interest. If current risk estimates are correct, these studies have very little chance of detecting risk, but can still be used to provide useful upper limits on risks. The studies are also adequate to detect serious underestimation of risks. 36 refs., 3 figs., 3 tabs

Biological influence from low dose and low-dose rate radiation

International Nuclear Information System (INIS)

Magae, Junji

2007-01-01

Although living organisms have defense mechanisms for radioadaptive response, the influence is considered to vary qualitatively and quantitatively for low dose and high dose, as well as for low-dose rate and high-dose rate. This article describes the bioresponse to low dose and low-dose rate. Among various biomolecules, DNA is the most sensitive to radiation, and accurate replication of DNA is an essential requirement for the survival of living organisms. Also, the influence of active enzymes resulted from the effect of radiation on enzymes in the body is larger than the direct influence of radiation on the body. After this, the article describes the carcinogenic risk by low-dose radiation, and then so-called Hormesis effect to create cancer inhibition effect by stimulating active physiology. (S.K.)

Burden of upper gastrointestinal symptoms in patients receiving low-dose acetylsalicylic acid for cardiovascular risk management

DEFF Research Database (Denmark)

Bytzer, Peter; Pratt, Stephen; Elkin, Eric

2013-01-01

Continuous low-dose acetylsalicylic acid (aspirin; ASA) is a mainstay of cardiovascular (CV) risk management. It is well established, however, that troublesome upper gastrointestinal (GI) symptoms are commonly experienced among low-dose ASA users.......Continuous low-dose acetylsalicylic acid (aspirin; ASA) is a mainstay of cardiovascular (CV) risk management. It is well established, however, that troublesome upper gastrointestinal (GI) symptoms are commonly experienced among low-dose ASA users....

Low-dose extrapolation of radiation health risks: some implications of uncertainty for radiation protection at low doses.

Science.gov (United States)

Land, Charles E

2009-11-01

Ionizing radiation is a known and well-quantified human cancer risk factor, based on a remarkably consistent body of information from epidemiological studies of exposed populations. Typical examples of risk estimation include use of Japanese atomic bomb survivor data to estimate future risk from radiation-related cancer among American patients receiving multiple computed tomography scans, persons affected by radioactive fallout, or persons whose livelihoods involve some radiation exposure, such as x-ray technicians, interventional radiologists, or shipyard workers. Our estimates of radiation-related risk are uncertain, reflecting statistical variation and our imperfect understanding of crucial assumptions that must be made if we are to apply existing epidemiological data to particular situations. Fortunately, that uncertainty is also highly quantifiable, and can be presented concisely and transparently. Radiation protection is ultimately a political process that involves consent by stakeholders, a diverse group that includes people who might be expected to be risk-averse and concerned with plausible upper limits on risk (how bad could it be?), cost-averse and concerned with lower limits on risk (can you prove there is a nontrivial risk at current dose levels?), or combining both points of view. How radiation-related risk is viewed by individuals and population subgroups also depends very much on perception of related benefit, which might be (for example) medical, economic, altruistic, or nonexistent. The following presentation follows the lead of National Council on Radiation Protection and Measurements (NCRP) Commentary 14, NCRP Report 126, and later documents in treating radiation protection from the viewpoint of quantitative uncertainty analysis.

Low-dose aspirin use and the risk of ovarian cancer in Denmark

DEFF Research Database (Denmark)

Baandrup, Lone; Kjaer, S K; Olsen, J H

2015-01-01

BACKGROUND: A comprehensive body of evidence has shown that aspirin has cancer-preventive effects, particularly against gastrointestinal cancer, but its effects on the risk of ovarian cancer are less well established. This nationwide case-control study examined the association between low......-dose aspirin and the risk of ovarian cancer. PATIENTS AND METHODS: We identified all patients in the Danish Cancer Registry aged 30-84 years old with a histologically verified first diagnosis of epithelial ovarian cancer during 2000-2011. Each patient was sex- and age-matched to 15 population controls using...... risk-set sampling. Prescription use, comorbidity, reproductive history, and demographic characteristics data were obtained from nationwide registries. The use of low-dose (75-150 mg) aspirin was defined according to the dose as well as the duration and consistency of use. Conditional logistic...

Summary of the BEIR V committee's estimates of genetic risks

International Nuclear Information System (INIS)

Grahn, D.

1990-01-01

The Committee on the Biological Effects of Ionizing Radiations (BEIR V) was constituted in late 1986 to conduct a comprehensive review of the biological effects of ionizing radiations focusing on information reported since the conclusion of the 1980 BEIR study, and to provide new estimates of the risks of genetic and somatic effects in humans due to low-level exposures of ionizing radiation. The Committee preferred the doubling-dose method of genetic risk estimation over the direct method. Data from animal (mouse) studies provide a median value of 100 to 114 cGy for long-term low dose rate exposure doubling doses. These values are lower than the median from human studies. The BEIR Committee believed that a doubling dose of 100 cGy would be a prudent value leading to conservative estimates. The estimated risks themselves are not much different from those generated by previous BEIR committees, UNSCEAR, and other published estimates. The Committee estimates that between 100 and 200 added cases per million live births will be observed at genetic equilibrium if the population is exposed each generation to a dose of 0.01 Sv (1 rem). Nearly half ware attributed to clinically mild dominant defects, and the balance to congenital abnormalities. (L.L.) (2 tabs.)

Toxicity risk of non-target organs at risk receiving low-dose radiation: case report

International Nuclear Information System (INIS)

Shueng, Pei-Wei; Lin, Shih-Chiang; Chang, Hou-Tai; Chong, Ngot-Swan; Chen, Yu-Jen; Wang, Li-Ying; Hsieh, Yen-Ping; Hsieh, Chen-Hsi

2009-01-01

The spine is the most common site for bone metastases. Radiation therapy is a common treatment for palliation of pain and for prevention or treatment of spinal cord compression. Helical tomotherapy (HT), a new image-guided intensity modulated radiotherapy (IMRT), delivers highly conformal dose distributions and provides an impressive ability to spare adjacent organs at risk, thus increasing the local control of spinal column metastases and decreasing the potential risk of critical organs under treatment. However, there are a lot of non-target organs at risk (OARs) occupied by low dose with underestimate in this modern rotational IMRT treatment. Herein, we report a case of a pathologic compression fracture of the T9 vertebra in a 55-year-old patient with cholangiocarcinoma. The patient underwent HT at a dose of 30 Gy/10 fractions delivered to T8-T10 for symptom relief. Two weeks after the radiotherapy had been completed, the first course of chemotherapy comprising gemcitabine, fluorouracil, and leucovorin was administered. After two weeks of chemotherapy, however, the patient developed progressive dyspnea. A computed tomography scan of the chest revealed an interstitial pattern with traction bronchiectasis, diffuse ground-glass opacities, and cystic change with fibrosis. Acute radiation pneumonitis was diagnosed. Oncologists should be alert to the potential risk of radiation toxicities caused by low dose off-targets and abscopal effects even with highly conformal radiotherapy

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

Science.gov (United States)

Cancer Risks Attributable to Low Doses of Ionizing Radiation - What Do We Really Know?AbstractHigh doses of ionizing radiation clearly produce deleterious consequences in humans including, but not exclusively, cancer induction. At very low radiation doses the situatio...

Radiation exposure to examiners and patients during therapeutic ERCP: Dose optimisation and risk estimation

International Nuclear Information System (INIS)

Sulieman, A.; Kappas, K.; Theodorou, K.; Paroutoglou, G.; Kapatenakis, A.; Kapsoritakis, A.; Potamianos, S.; Vlychou, M.; Fezoulidis, I.

2008-01-01

Aim: This study intended to optimise the radiation dose during therapeutic ERCP, and to estimate the risk for examiners and patients, to compare the doses based on available data obtained by other researchers and reference levels recommended by international organizations, and to evaluate the technique applied in order to reduce patient and examiners doses. Materials and Methods: 153 patients were studied in two Gastroenterology Departments, (group A, 111; group B, 42). Thermoluminescent dosimeters (TLD) were used to measure the staff and patients entrance surface dose (ESD) at different body sites. Results: The mean ESD, exit and thyroid surface dose per procedure was estimated to be 68.75 mGy, 3.45 mGy and 0.67 mGy, respectively. The mean patient effective dose was 3.44 mSv, and the cancer risk per procedure was estimated to be 190 x10 -6 . The effective dose for the first, second and third examiner was 0.4 μSv, 0.2 μSv and 5.0 μSv, respectively. Conclusion: The patient dose can be optimized by the presence of two experienced examiners and reduction of radiographic images. The examiners should use a wrap around lead apron since the highest dose originating from the X-ray tube, is incident on their side and back. The current formulae, which exist, underestimate the effective dose to the examiners, when they are applied for ERCP procedures. For both patients and examiners, our results were up to 60% lower compared to the lowest values found in previous studies. (authors)

Estimation of breast dose and cancer risk in chest and abdomen CT procedures

International Nuclear Information System (INIS)

Eltahir, Suha Abubaker Ali

2013-05-01

The use of CT in medical diagnosis delivers radiation doses to patents that are higher than those from other radiological procedures. Lack of optimized protocols be an additional source of increased dose in developing countries. The aims of this study are first, to measure patient doses during CT chest and abdomen procedures, second, to estimate the radiation dose to the breast, and third to quantify the radiation risks during the procedures. Patient doses from two common CT examinations were obtained from four hospitals in Khartoum.The patient doses were estimated using measurement of CT dose indexes (CTDI), exposure-related parameters, and the IMPACT spreadsheet based on NRPB conversion factors. A large variation of mean organ doses among hospitals was observed for similar CT examinations. These variations largely originated from different CT scanning protocols used in different hospitals and scanner type. The largest range was found for CT of the chest, for which the dose varied from 2.3 to 47 (average 24.7) mSv and for abdomen CT, it was 1.6 to 18.8 (average 10.2) mSv. Radiation dose to the breast ranged from 1.6 to 32.9 mSv for the chest and 1.1 to 13.2 mSv for the abdomen. The radiation risk per procedure was high. The obtained values were mostly higher than the values of organ doses reported from the other studies. It was concluded that current clinical chest and abdomen protocols result in variable radiation doses to the breast. The magnitude of exposure may have implications for imaging strategies.(Author)

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

International Nuclear Information System (INIS)

Metz-Flamant, Camille

2011-01-01

exposure. Our study finds a risk of leukemia associated with chronic external exposure and allows taking into account modifying factors of this relation. Additional follow-up allows to improve the precision of the estimated dose-response relationship. A combined analysis including the present cohort and other nuclear cohorts could quantify more precisely the risks associated with low doses at low dose rates, in order to validate current underlying hypotheses of the radiation protection system. (author)

Estimation of cancer risks from radiotherapy of benign diseases

International Nuclear Information System (INIS)

Trott, K.R.; Kamprad, F.

2006-01-01

Background: The effective-dose method which was proposed by the ICRP (International Commission of Radiation Protection) for the estimation of risk to the general population from occupational or environmental, low-dose radiation exposure is not adequate for estimating the risk of cancer induction by radiotherapy of malignant or nonmalignant diseases. Methods:The risk of cancer induction by radiotherapy of benign diseases should be based on epidemiologic data directly derived from follow-up studies of patients who had been given radiotherapy for nonmalignant diseases in the past. Results: Risk factors were derived from epidemiologic studies of patients treated with irradiation for nonmalignant diseases to be used for selecting treatment options and optimizing treatment procedures. Conclusion: In most cases, cancer risks estimated by the effective-dose method may overestimate the true risks by one order of magnitude, yet in other cases even may underestimate it. The proposed method using organ-specific risk factors may be more suitable for treatment planning. (orig.)

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

Energy Technology Data Exchange (ETDEWEB)

Scott, Bobby, R., Ph.D.

2003-06-27

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

Second International MELODI Workshop on Low Dose Risk Research - Slides of the presentations

International Nuclear Information System (INIS)

Repussard, J.; Weiss, W.; Quintana Trias, O.; Rosario Perez, M. del; Andersen, M.; Rudiger Trott, K.; Ottolenghi, A.; Smyth, V.; Graw, J.; Little, M.P.; Yonai, S.; Barcellos-Hoff, M.H.; Bouffler, S.; Chevillard, S.; Jeggo, P.; Sabatier, L.; Baatout, S.; Niwa, O.; Oesch, F.; Atkinson, M.; Averbeck, D.; Lloyd, D.; O'Neill, P.

2011-01-01

The MELODI (Multidisciplinary European Low Dose Initiative) mission is to impulse low dose risk research in Europe through a strategic research agenda (SRA) and road-map of priorities. The last presentation is dedicated to the SRA and its preference research programs. The other presentations deal principally with the low-dose exposure in medical uses of ionizing radiations, radiosensitivity, radiation-induced cataracts, or epidemiology and radiobiology of cardiovascular disease. This document is composed of the slides of the presentations

Estimation of the total effective dose from low-dose CT scans and radiopharmaceutical administrations delivered to patients undergoing SPECT/CT explorations

International Nuclear Information System (INIS)

Montes, C.; Hernandez, J.; Gomez-Caminero, F.; Garcia, S.; Martin, C.; Rosero, A.; Tamayo, P.

2013-01-01

Hybrid imaging, such as single photon emission computed tomography (SPECT)/CT, is used in routine clinical practice, allowing coregistered images of the functional and structural information provided by the two imaging modalities. However, this multimodality imaging may mean that patients are exposed to a higher radiation dose than those receiving SPECT alone. The study aimed to determine the radiation exposure of patients who had undergone SPECT/CT examinations and to relate this to the Background Equivalent Radiation Time (BERT). 145 SPECT/CT studies were used to estimate the total effective dose to patients due to both radiopharmaceutical administrations and low-dose CT scans. The CT contribution was estimated by the Dose-Length Product method. Specific conversion coefficients were calculated for SPECT explorations. The radiation dose from low-dose CTs ranged between 0.6 mSv for head and neck CT and 2.6 mSv for whole body CT scan, representing a maximum of 1 year of background radiation exposure. These values represent a decrease of 80-85% with respect to the radiation dose from diagnostic CT. The radiation exposure from radiopharmaceutical administration varied from 2.1 mSv for stress myocardial perfusion SPECT to 26 mSv for gallium SPECT in patients with lymphoma. The BERT ranged from 1 to 11 years. The contribution of low-dose CT scans to the total radiation dose to patients undergoing SPECT/CT examinations is relatively low compared with the effective dose from radiopharmaceutical administration. When a CT scan is only acquired for anatomical localization and attenuation correction, low-dose CT scan is justified on the basis of its lower dose. (author)

Risks of circulatory diseases among Mayak PA workers with radiation doses estimated using the improved Mayak Worker Dosimetry System 2008

Energy Technology Data Exchange (ETDEWEB)

Moseeva, Maria B.; Azizova, Tamara V.; Grigoryeva, Evgenia S. [Southern Urals Biophysics Institute (SUBI), Ozyorsk, Chelyabinsk Region (Russian Federation); Haylock, Richard [Public Health of England, London (United Kingdom)

2014-05-15

The new Mayak Worker Dosimetry System 2008 (MWDS-2008) was published in 2013 and supersedes the Doses-2005 dosimetry system for Mayak Production Association (PA) workers. It provides revised external and internal dose estimates based on the updated occupational history data. Using MWDS-2008, a cohort of 18,856 workers first employed at one of the main Mayak PA plants during 1948-1972 and followed up to 2005 was identified. Incidence and mortality risks from ischemic heart disease (IHD) (International Classification of Diseases (ICD)-9 codes 410-414) and from cerebrovascular diseases (CVD) (ICD-9 codes 430-438) were examined in this cohort and compared with previously published risk estimates in the same cohort based on the Doses-2005 dosimetry system. Significant associations were observed between doses from external gamma-rays and IHD and CVD incidence and also between internal doses from alpha-radiation and IHD mortality and CVD incidence. The estimates of excess relative risk (ERR)/Gy were consistent with those estimates from the previous studies based on Doses-2005 system apart from the relationship between CVD incidence and internal liver dose where the ERR/Gy based on MWDS-2008 was just over three times higher than the corresponding estimate based on Doses-2005 system. Adjustment for smoking status did not show any effect on the estimates of risk from internal alpha-particle exposure. (orig.)

Re-distribution of brachytherapy dose using a differential dose prescription adapted to risk of local failure in low-risk prostate cancer patients

DEFF Research Database (Denmark)

Rylander, Susanne; Polders, Daniel; Steggerda, Marcel J

2015-01-01

BACKGROUND AND PURPOSE: We investigated the application of a differential target- and dose prescription concept for low-dose-rate prostate brachytherapy (LDR-BT), involving a re-distribution of dose according to risk of local failure and treatment-related morbidity. MATERIAL AND METHODS: Our study......- and dose prescription concept of prescribing a lower dose to the whole gland and an escalated dose to the GTV using LDR-BT seed planning was technically feasible and resulted in a significant dose-reduction to urethra and bladder neck....

Estimation of breast doses and breast cancer risk associated with repeated fluoroscopic chest examinations of women with tuberculosis

International Nuclear Information System (INIS)

Boice, J.D. Jr.; Rosenstein, M.; Trout, E.D.

1978-01-01

A methodology is presented to estimate cumulative breast dose and breast cancer risk for women exposed to repeated fluoroscopic chest examinations during air collapse therapy for pulmonary tuberculosis. Medical record abstraction, physician interview, patient contact, machine exposure measurements, and absorbed dose computations were combined to estimate average breast doses for 1047 Massachusetts women who were treated between 1930 and 1954. The methodology presented considers breast size and composition, patient orientation, x-ray field size and location, beam quality, type of examination, machine exposure rate, and exposure time during fluoroscopic examinations. The best estimate for the risk of radiation-induced cancer for the women living longer than 10 years after initial fluoroscopic exposure is 6.2 excess breast cancers per million woman-year-rad with 90% confidence limits of 2.8 and 10.7 cancers/10 6 WY-rad. When breast cancer risk is considered as a function of absorbed dose in the breast, instead of as a function of the number of fluoroscopic examinations, a linear dose--response relationship over the range of estimated doses is consistent with the data. However, because of the uncertainty due to small-sample variability and because of the wide range of assumptions regarding certain fluoroscopy conditions, other dose--response relationships are compatible with the data

Problems linked to effects of ionizing radiations low doses

International Nuclear Information System (INIS)

Anon.

1995-10-01

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

New use of low-dose aspirin and risk of colorectal cancer by stage at diagnosis: a nested case-control study in UK general practice.

Science.gov (United States)

García Rodríguez, Luis A; Soriano-Gabarró, Montse; Bromley, Susan; Lanas, Angel; Cea Soriano, Lucía

2017-09-07

Evidence from clinical trial populations suggests low-dose aspirin reduces the risk of colorectal cancer (CRC). Part of this reduction in risk might be due to protection against metastatic disease. We investigated the risk of CRC among new-users of low-dose aspirin (75-300 mg), including risk by stage at diagnosis. Using The Health Improvement Network, we conducted a cohort study with nested case-control analysis. Two cohorts (N = 170,336 each) aged 40-89 years from 2000 to 2009 and free of cancer were identified: i) new-users of low-dose aspirin, ii) non-users of low-dose aspirin, at start of follow-up, matched by age, sex and previous primary care practitioner visits. Patients were followed for up to 12 years to identify incident CRC. 10,000 frequency-matched controls were selected by incidence density sampling where the odds ratio is an unbiased estimator of the incidence rate ratio (RR). RRs with 95% confidence intervals were calculated. Low-dose aspirin use was classified 'as-treated' independent from baseline exposure status to account for changes in exposure during follow-up. Current users of low-dose aspirin (use on the index date or in the previous 90 days) had a significantly reduced risk of CRC, RR 0.66 (95% CI 0.60-0.74). The reduction in risk was apparent across all age groups, and was unrelated to dose, indication, gender, CRC location or case-fatality status. Reduced risks occurred throughout treatment duration and with all low-dose aspirin doses. RRs by aspirin indication were 0.71 (0·63-0·79) and 0.60 (0.53-0.68) for primary and secondary cardiovascular protection, respectively. Among cases with staging information (n = 1421), RRs for current use of low-dose aspirin were 0.94 (0.66-1.33) for Dukes Stage A CRC, 0.54 (0.42-0.68) for Dukes B, 0.71 (0.56-0.91) for Dukes C, and 0.60 (0.48-0.74) for Dukes D. After 5 years' therapy, the RR for Dukes Stage A CRC was 0.53 (0.24-1.19). Patients starting low-dose aspirin therapy have a reduced

A long-term risk-benefit analysis of low-dose aspirin in primary prevention.

Science.gov (United States)

Wu, I-Chen; Hsieh, Hui-Min; Yu, Fang-Jung; Wu, Meng-Chieh; Wu, Tzung-Shiun; Wu, Ming-Tsang

2016-02-01

The long-term risk-benefit effect of occasional and regular use of low-dose aspirin (≤ 100 mg per day) in primary prevention of vascular diseases and cancers was calculated. One representative database of 1 000 000 participants from Taiwan's National Health Insurance scheme in 1997-2000 was used. The potential study subjects were those aged 30-95 years, were found not to have been prescribed aspirin before 1 January 2000, but to have first been prescribed low-dose aspirin (≤ 100 mg per day) after that date and were followed up to 31 December 2009. Participants prescribed low-dose aspirin risk. A total of 1720 pairs were analysed. During the study period, haemorrhage and ischaemia occurred in 25 (1·45%) and 67 participants (3·90%) in occasional users and 69 (4·01%) and 100 participants (5·81%) in regular users, whereas cancer occurred in 32 participants (1·86%) in occasional users and 26 participants (1·51%) in regular users. The crude and adjusted net clinical risks of low-dose aspirin use between the two frequency of users (≥ 80% vs. prevention against major vascular diseases and cancer. © 2015 Stichting European Society for Clinical Investigation Journal Foundation.

Patient- and cohort-specific dose and risk estimation for abdominopelvic CT: a study based on 100 patients

Science.gov (United States)

Tian, Xiaoyu; Li, Xiang; Segars, W. Paul; Frush, Donald P.; Samei, Ehsan

2012-03-01

The purpose of this work was twofold: (a) to estimate patient- and cohort-specific radiation dose and cancer risk index for abdominopelvic computer tomography (CT) scans; (b) to evaluate the effects of patient anatomical characteristics (size, age, and gender) and CT scanner model on dose and risk conversion coefficients. The study included 100 patient models (42 pediatric models, 58 adult models) and multi-detector array CT scanners from two commercial manufacturers (LightSpeed VCT, GE Healthcare; SOMATOM Definition Flash, Siemens Healthcare). A previously-validated Monte Carlo program was used to simulate organ dose for each patient model and each scanner, from which DLP-normalized-effective dose (k factor) and DLP-normalized-risk index values (q factor) were derived. The k factor showed exponential decrease with increasing patient size. For a given gender, q factor showed exponential decrease with both increasing patient size and patient age. The discrepancies in k and q factors across scanners were on average 8% and 15%, respectively. This study demonstrates the feasibility of estimating patient-specific organ dose and cohort-specific effective dose and risk index in abdominopelvic CT requiring only the knowledge of patient size, gender, and age.

Evaluation of organ dose and estimation of risk due to the abdominal region radiography in Indian adults

International Nuclear Information System (INIS)

Kumaresan, M.; Chaubey, Ajay; Kantharia, Surita; Karira, V.; Kumar, Rajesh; Biju, K.; Rao, B.S.

2006-01-01

Organ dose, risk of carcinogenesis and genetic effect due to the abdominal region radiography in Indian adult with the help of Monte-Carlo MCNP code by measuring the entrance skin dose by LiF: Mg, Cu, P TL phosphor and the risk coefficients provided by ICRP 60 were estimated. The entrance skin dose for abdominal region radiography was ranges from 2.75 mSv to 18.88 mSv while average entrance skin dose was 8.3 mSv. The bladder, testes and ovary are the important organ those are getting higher dose. The maximum dose for testes, ovary and bladder is 5.37 mSv, 1.45 mSv and 4.74 mSv respectively. The frequency of occurrence of fatal cancers and serious genetic disorders as a consequence of abdominal region radiography ranges from 0.1 to 38.8 risk/10 6 of fatal cancer. Although the estimated risks are small but cannot be neglected. It is important to avoid unnecessary repetitions and also to carry out proper quality assurance tests on the equipment and in the long run it will help reduce the risks and maximize the benefits of radiodiagnosis. These studies may lead to setting up of national reference levels for the diagnostic procedures India. (author)

Genetic radiation risks: a neglected topic in the low dose debate

Directory of Open Access Journals (Sweden)

Inge Schmitz-Feuerhake

2016-01-01

Full Text Available Objectives To investigate the accuracy and scientific validity of the current very low risk factor for hereditary diseases in humans following exposures to ionizing radiation adopted by the United Nations Scientific Committee on the Effects of Atomic Radiation and the International Commission on Radiological Protection. The value is based on experiments on mice due to reportedly absent effects in the Japanese atomic bomb (Abomb survivors. Methods To review the published evidence for heritable effects after ionising radiation exposures particularly, but not restricted to, populations exposed to contamination from the Chernobyl accident and from atmospheric nuclear test fallout. To make a compilation of findings about early deaths, congenital malformations, Down’s syndrome, cancer and other genetic effects observed in humans after the exposure of the parents. To also examine more closely the evidence from the Japanese A-bomb epidemiology and discuss its scientific validity. Results Nearly all types of hereditary defects were found at doses as low as one to 10 mSv. We discuss the clash between the current risk model and these observations on the basis of biological mechanism and assumptions about linear relationships between dose and effect in neonatal and foetal epidemiology. The evidence supports a dose response relationship which is non-linear and is either biphasic or supralinear (hogs-back and largely either saturates or falls above 10 mSv. Conclusions We conclude that the current risk model for heritable effects of radiation is unsafe. The dose response relationship is non-linear with the greatest effects at the lowest doses. Using Chernobyl data we derive an excess relative risk for all malformations of 1.0 per 10 mSv cumulative dose. The safety of the Japanese A-bomb epidemiology is argued to be both scientifically and philosophically questionable owing to errors in the choice of control groups, omission of internal exposure effects and

Space Radiation Heart Disease Risk Estimates for Lunar and Mars Missions

Science.gov (United States)

Cucinotta, Francis A.; Chappell, Lori; Kim, Myung-Hee

2010-01-01

The NASA Space Radiation Program performs research on the risks of late effects from space radiation for cancer, neurological disorders, cataracts, and heart disease. For mortality risks, an aggregate over all risks should be considered as well as projection of the life loss per radiation induced death. We report on a triple detriment life-table approach to combine cancer and heart disease risks. Epidemiology results show extensive heterogeneity between populations for distinct components of the overall heart disease risks including hypertension, ischaemic heart disease, stroke, and cerebrovascular diseases. We report on an update to our previous heart disease estimates for Heart disease (ICD9 390-429) and Stroke (ICD9 430-438), and other sub-groups using recent meta-analysis results for various exposed radiation cohorts to low LET radiation. Results for multiplicative and additive risk transfer models are considered using baseline rates for US males and female. Uncertainty analysis indicated heart mortality risks as low as zero, assuming a threshold dose for deterministic effects, and projections approaching one-third of the overall cancer risk. Medan life-loss per death estimates were significantly less than that of solid cancer and leukemias. Critical research questions to improve risks estimates for heart disease are distinctions in mechanisms at high doses (>2 Gy) and low to moderate doses (<2 Gy), and data and basic understanding of radiation doserate and quality effects, and individual sensitivity.

Radiation doses and risks from internal emitters

International Nuclear Information System (INIS)

Harrison, John; Day, Philip

2008-01-01

This review updates material prepared for the UK Government Committee Examining Radiation Risks from Internal Emitters (CERRIE) and also refers to the new recommendations of the International Commission on Radiological Protection (ICRP) and other recent developments. Two conclusions from CERRIE were that ICRP should clarify and elaborate its advice on the use of its dose quantities, equivalent and effective dose, and that more attention should be paid to uncertainties in dose and risk estimates and their implications. The new ICRP recommendations provide explanations of the calculation and intended purpose of the protection quantities, but further advice on their use would be helpful. The new recommendations refer to the importance of understanding uncertainties in estimates of dose and risk, although methods for doing this are not suggested. Dose coefficients (Sv per Bq intake) for the inhalation or ingestion of radionuclides are published as reference values without uncertainty. The primary purpose of equivalent and effective dose is to enable the summation of doses from different radionuclides and from external sources for comparison with dose limits, constraints and reference levels that relate to stochastic risks of whole-body radiation exposure. Doses are calculated using defined biokinetic and dosimetric models, including reference anatomical data for the organs and tissues of the human body. Radiation weighting factors are used to adjust for the different effectiveness of different radiation types, per unit absorbed dose (Gy), in causing stochastic effects at low doses and dose rates. Tissue weighting factors are used to take account of the contribution of individual organs and tissues to overall detriment from cancer and hereditary effects, providing a simple set of rounded values chosen on the basis of age- and sex-averaged values of relative detriment. While the definition of absorbed dose has the scientific rigour required of a basic physical quantity

The MIRD method of estimating absorbed dose

International Nuclear Information System (INIS)

Weber, D.A.

1991-01-01

The estimate of absorbed radiation dose from internal emitters provides the information required to assess the radiation risk associated with the administration of radiopharmaceuticals for medical applications. The MIRD (Medical Internal Radiation Dose) system of dose calculation provides a systematic approach to combining the biologic distribution data and clearance data of radiopharmaceuticals and the physical properties of radionuclides to obtain dose estimates. This tutorial presents a review of the MIRD schema, the derivation of the equations used to calculate absorbed dose, and shows how the MIRD schema can be applied to estimate dose from radiopharmaceuticals used in nuclear medicine

Publication of new results from the INWORKS epidemiological study about the risk of cancer among nuclear industry workers chronically exposed to low ionizing radiation doses

International Nuclear Information System (INIS)

2015-01-01

In this cohort study, 308297 workers in the nuclear industry from France, the United Kingdom, and the United States with detailed monitoring data for external exposure to ionising radiation were linked to death registries. Excess relative rate per Gy of radiation dose for mortality from cancer was estimated. Follow-up encompassed 8.2 million person years. Of 66632 known deaths by the end of follow-up, 17?957 were due to solid cancers. Results suggest a linear increase in the rate of cancer with increasing radiation exposure. The average cumulative colon dose estimated among exposed workers was 20.9 mGy (median 4.1 mGy). The estimated rate of mortality from all cancers excluding leukaemia increased with cumulative dose by 48% per Gy (90% confidence interval 20% to 79%), lagged by 10 years. Similar associations were seen for mortality from all solid cancers (47% (18% to 79%)), and within each country. The estimated association over the dose range of 0-100 mGy was similar in magnitude to that obtained over the entire dose range but less precise. Smoking and occupational asbestos exposure are potential confounders; however, exclusion of deaths from lung cancer and pleural cancer did not affect the estimated association. Despite substantial efforts to characterise the performance of the radiation dosimeters used, the possibility of measurement error remains. The study provides a direct estimate of the association between protracted low dose exposure to ionising radiation and solid cancer mortality. Although high dose rate exposures are thought to be more dangerous than low dose rate exposures, the risk per unit of radiation dose for cancer among radiation workers was similar to estimates derived from studies of Japanese atomic bomb survivors. Quantifying the cancer risks associated with protracted radiation exposures can help strengthen the foundation for radiation protection standards

Low Dose Radiation Cancer Risks: Epidemiological and Toxicological Models

Energy Technology Data Exchange (ETDEWEB)

David G. Hoel, PhD

2012-04-19

The basic purpose of this one year research grant was to extend the two stage clonal expansion model (TSCE) of carcinogenesis to exposures other than the usual single acute exposure. The two-stage clonal expansion model of carcinogenesis incorporates the biological process of carcinogenesis, which involves two mutations and the clonal proliferation of the intermediate cells, in a stochastic, mathematical way. The current TSCE model serves a general purpose of acute exposure models but requires numerical computation of both the survival and hazard functions. The primary objective of this research project was to develop the analytical expressions for the survival function and the hazard function of the occurrence of the first cancer cell for acute, continuous and multiple exposure cases within the framework of the piece-wise constant parameter two-stage clonal expansion model of carcinogenesis. For acute exposure and multiple exposures of acute series, it is either only allowed to have the first mutation rate vary with the dose, or to have all the parameters be dose dependent; for multiple exposures of continuous exposures, all the parameters are allowed to vary with the dose. With these analytical functions, it becomes easy to evaluate the risks of cancer and allows one to deal with the various exposure patterns in cancer risk assessment. A second objective was to apply the TSCE model with varing continuous exposures from the cancer studies of inhaled plutonium in beagle dogs. Using step functions to estimate the retention functions of the pulmonary exposure of plutonium the multiple exposure versions of the TSCE model was to be used to estimate the beagle dog lung cancer risks. The mathematical equations of the multiple exposure versions of the TSCE model were developed. A draft manuscript which is attached provides the results of this mathematical work. The application work using the beagle dog data from plutonium exposure has not been completed due to the fact

Carcinogenesis induced by low-dose radiation

Directory of Open Access Journals (Sweden)

Piotrowski Igor

2017-11-01

Full Text Available Although the effects of high dose radiation on human cells and tissues are relatively well defined, there is no consensus regarding the effects of low and very low radiation doses on the organism. Ionizing radiation has been shown to induce gene mutations and chromosome aberrations which are known to be involved in the process of carcinogenesis. The induction of secondary cancers is a challenging long-term side effect in oncologic patients treated with radiation. Medical sources of radiation like intensity modulated radiotherapy used in cancer treatment and computed tomography used in diagnostics, deliver very low doses of radiation to large volumes of healthy tissue, which might contribute to increased cancer rates in long surviving patients and in the general population. Research shows that because of the phenomena characteristic for low dose radiation the risk of cancer induction from exposure of healthy tissues to low dose radiation can be greater than the risk calculated from linear no-threshold model. Epidemiological data collected from radiation workers and atomic bomb survivors confirms that exposure to low dose radiation can contribute to increased cancer risk and also that the risk might correlate with the age at exposure.

Stereotactic body radiation therapy for low- and low-intermediate risk prostate cancer: Is there a dose effect?

Directory of Open Access Journals (Sweden)

Alan Jay Katz

2011-12-01

Full Text Available This study examines the efficacy and toxicity of two stereotactic body radiation therapy (SBRT dose regimens for treatment of early prostate cancer. Forty-one patients treated with 35 Gy were matched with 41 patients treated with 36.25 Gy. Both patient groups received SBRT in 5 fractions over 5 consecutive days using the CyberKnife. Each group had 37 low-risk patients and 4 intermediate-risk patients. No statistically significant differences were present for age, prostate volume, PSA, Gleason score, stage, or risk between the groups. The dose was prescribed to the 83-87% isodose line to cover the prostate and a 5-mm margin all around, except 3 mm posteriorly. The overall median follow-up is 51 months (range, 45-58 months with a median 54 months and 48 months follow-up for the 35-Gy and 36.25-Gy dose groups, respectively. One biochemical failure occurred in each group yielding a 97.5% freedom from biochemical failure. The PSA response has been favorable for all patients with a mean PSA of 0.1 ng/ml at 4-years. Overall toxicity has been mild with 5% late grade 2 rectal toxicity in both dose groups. Late grade 1 urinary toxicity was equivalent between groups; grade 2 urinary toxicity was 5% (2/41 patients and 10% (4/41 patients in the 35-Gy and 36.25-Gy dose groups (p = 0.6969, respectively. Overall, the highly favorable PSA response, limited biochemical failures, limited toxicity, and limited impact on quality of life in these low- to low-intermediate-risk patients are supportive of excellent long-term results for CyberKnife delivered SBRT.

Harderian Gland Tumorigenesis: Low-Dose and LET Response

Energy Technology Data Exchange (ETDEWEB)

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

2016-04-19

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

The researches on the effects of low doses irradiation

International Nuclear Information System (INIS)

2009-02-01

All research conducted as part of 'Risc-Rad' and those conducted by actors in international programs on low doses allow progress in understanding mechanisms of carcinogenesis associated with irradiation. The data do not question the use in radiation protection, risk estimation models based on a linear increase of the risk with the dose of radiation. Nevertheless, they show that the nature of biological responses induced by low doses of radiation has differences with the responses induced by high doses of radiation. They also show the diversity of effects/dose relationships as the mechanism observed and the importance of genetic predisposition in the individual sensitivity to low doses of radiation. It is therefore essential to continue to bring new data to better understand the complex biological effects and their impact on the establishment of radiation protection standards. In addition, the results have often been at the cellular level. The diversity of responses induced by radiations is also a function of cell types observed, the aging of cells and tissue organization. It is essential to strengthen researches at the tissue and body level, involving in vitro and in vivo approaches while testing the hypothesis in epidemiology with a global approach to systems biology. Over the past four years, the collaboration between partners of 'Risc-Rad' using experimental biology approaches and those using mathematical modeling techniques aimed at developing a new model describing the carcinogenesis induced by low radiation doses. On an other hand, The High level expert group on European low dose risk research (H.L.E.G.) develop programmes in the area of low dose irradiation (Germany, Finland, France, Italy and United Kingdom). It proposed a structure of trans national government called M.E.L.O.D.I. ( multidisciplinary european low dose initiative). Its objective is to structure and integrate European research by gathering around a common programme of multidisciplinary

Low-dose ionizing radiation – is it harmful to health?

Energy Technology Data Exchange (ETDEWEB)

Sullivan, A. H. [CERN Radiation Protection Group (European Organization for Nuclear Research (CERN))

1987-09-15

A conference on the health effects of low-dose ionizing radiation organized in London earlier this year by the British Nuclear Energy Society brought together epidemiologists who have been investigating the mortality of workers from the nuclear industry in an attempt to put low-level radiation risk estimates on a scientific basis.

Estimated risk of radiation-induced cancer from paediatric chest CT: two-year cohort study

Energy Technology Data Exchange (ETDEWEB)

Niemann, Tilo [Cantonal Hospital Baden, Department of Radiology, Baden (Switzerland); University Lille Nord de France, Department of Thoracic Imaging, Hospital Calmette, Lille (France); Colas, Lucie; Santangelo, Teresa; Faivre, Jean Baptiste; Remy, Jacques; Remy-Jardin, Martine [University Lille Nord de France, Department of Thoracic Imaging, Hospital Calmette, Lille (France); Roser, Hans W.; Bremerich, Jens [University of Basel Hospital, Clinic of Radiology and Nuclear Medicine, Medical Physics, Basel (Switzerland)

2015-03-01

The increasing absolute number of paediatric CT scans raises concern about the safety and efficacy and the effects of consecutive diagnostic ionising radiation. To demonstrate a method to evaluate the lifetime attributable risk of cancer incidence/mortality due to a single low-dose helical chest CT in a two-year patient cohort. A two-year cohort of 522 paediatric helical chest CT scans acquired using a dedicated low-dose protocol were analysed retrospectively. Patient-specific estimations of radiation doses were modelled using three different mathematical phantoms. Per-organ attributable cancer risk was then estimated using epidemiological models. Additional comparison was provided for naturally occurring risks. Total lifetime attributable risk of cancer incidence remains low for all age and sex categories, being highest in female neonates (0.34%). Summation of all cancer sites analysed raised the relative lifetime attributable risk of organ cancer incidence up to 3.6% in female neonates and 2.1% in male neonates. Using dedicated scan protocols, total lifetime attributable risk of cancer incidence and mortality for chest CT is estimated low for paediatric chest CT, being highest for female neonates. (orig.)

Risks of low-level radiation - the evidence of epidemiology

International Nuclear Information System (INIS)

Gloag, D.

1980-01-01

The difficulties involved in estimating risks from very low levels of radiation and the use of dose-response models for cancer incidence are discussed with reference to the third BEIR Committee report on the Effects on Populations of Exposure to low levels of Ionizing Radiation (1980). Cancer risk estimates derived from different epidemiological studies are reviewed. They include atom bomb survivors, medically irradiated groups and occupational groups. (36 references). (author)

3D conditional generative adversarial networks for high-quality PET image estimation at low dose.

Science.gov (United States)

Wang, Yan; Yu, Biting; Wang, Lei; Zu, Chen; Lalush, David S; Lin, Weili; Wu, Xi; Zhou, Jiliu; Shen, Dinggang; Zhou, Luping

2018-07-01

Positron emission tomography (PET) is a widely used imaging modality, providing insight into both the biochemical and physiological processes of human body. Usually, a full dose radioactive tracer is required to obtain high-quality PET images for clinical needs. This inevitably raises concerns about potential health hazards. On the other hand, dose reduction may cause the increased noise in the reconstructed PET images, which impacts the image quality to a certain extent. In this paper, in order to reduce the radiation exposure while maintaining the high quality of PET images, we propose a novel method based on 3D conditional generative adversarial networks (3D c-GANs) to estimate the high-quality full-dose PET images from low-dose ones. Generative adversarial networks (GANs) include a generator network and a discriminator network which are trained simultaneously with the goal of one beating the other. Similar to GANs, in the proposed 3D c-GANs, we condition the model on an input low-dose PET image and generate a corresponding output full-dose PET image. Specifically, to render the same underlying information between the low-dose and full-dose PET images, a 3D U-net-like deep architecture which can combine hierarchical features by using skip connection is designed as the generator network to synthesize the full-dose image. In order to guarantee the synthesized PET image to be close to the real one, we take into account of the estimation error loss in addition to the discriminator feedback to train the generator network. Furthermore, a concatenated 3D c-GANs based progressive refinement scheme is also proposed to further improve the quality of estimated images. Validation was done on a real human brain dataset including both the normal subjects and the subjects diagnosed as mild cognitive impairment (MCI). Experimental results show that our proposed 3D c-GANs method outperforms the benchmark methods and achieves much better performance than the state

Late effects of low doses and dose rates

International Nuclear Information System (INIS)

Paretzke, H.G.

1980-01-01

This paper outlines the spectrum of problems and approaches used in work on the derivation of quantitative prognoses of late effects in man of low doses and dose rates. The origins of principal problems encountered in radiation risks assessments, definitions and explanations of useful quantities, methods of deriving risk factors from biological and epidemiological data, and concepts of risk evaluation and problems of acceptance are individually discussed

Cancer risk at low doses of ionizing radiation. Artificial neural networks inference from atomic bomb survivors

International Nuclear Information System (INIS)

Sasaki, Masao S.; Tachibana, Akira; Takeda, Shunichi

2014-01-01

Cancer risk at low doses of ionizing radiation remains poorly defined because of ambiguity in the quantitative link to doses below 0.2 Sv in atomic bomb survivors in Hiroshima and Nagasaki arising from limitations in the statistical power and information available on overall radiation dose. To deal with these difficulties, a novel nonparametric statistics based on the ‘integrate-and-fire’ algorithm of artificial neural networks was developed and tested in cancer databases established by the Radiation Effects Research Foundation. The analysis revealed unique features at low doses that could not be accounted for by nominal exposure dose, including (1) the presence of a threshold that varied with organ, gender and age at exposure, and (2) a small but significant bumping increase in cancer risk at low doses in Nagasaki that probably reflects internal exposure to 239 Pu. The threshold was distinct from the canonical definition of zero effect in that it was manifested as negative excess relative risk, or suppression of background cancer rates. Such a unique tissue response at low doses of radiation exposure has been implicated in the context of the molecular basis of radiation–environment interplay in favor of recently emerging experimental evidence on DNA double-strand break repair pathway choice and its epigenetic memory by histone marking. (author)

Cancer and non-cancer risk at low doses of radiation: biological basis of radiation-environment interplay

International Nuclear Information System (INIS)

Sasaki, Masao S.

2013-01-01

Cancer and non-cancer risk at low doses of ionizing radiation remains poorly defined due to ambiguity at low doses caused by limitations in statistical power and information available on interplay with environment. To deal with these problems, a novel non-parametric statistics was developed based on artificial neural networks theorem and applied to cancer and non-cancer risk in A-bomb survivors. The analysis revealed several unique features at low doses that could not be accounted for by nominal radiation dose alone. They include (1) threshold that varies with organ, gender and age, including cardiovascular diseases, (2) prevalence of infectious diseases, and (3) suppression of pathogenesis of HTLV1. The threshold is unique as it is manifested as negative excess relative risk, a reduction of spontaneous rate at low doses. The response is consistent with currently emerging laboratory data on DNA double-strand break (DSB) repair pathway choice and its sustainability as epigenetic memory in accordance with histone code theory. In response to DSB, of radiation or DNA replication arrest origin, distinct and competitively operating repair pathways are instigated. Activation by low doses of restitution-directed canonical non-homologous end-joining (C-NHEJ) suppresses both error-prone alternative end-joining (Alt-NHEJ) and homologous recombination (HR). The latter two present major pathways to mutagenesis at stalled replication folk associated with endogenous and exogenous genotoxin such as tobacco smoke metabolites and AID-associated somatic hypermutation and class switch recombination in Ig gene. Suppression of these error-prone pathways by low doses of low LET radiation is consistent with the reduction of cancer occurrence by environmental genotoxin, immunodiversity and stable integration of retrovirus DNA, providing a significant modulator of dose linearity at low doses. Whole picture may bring about a new landscape of cancer and non-cancer molecular epidemiology which

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

International Nuclear Information System (INIS)

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

2015-01-01

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

Biological dose estimation in a radiation accident involving low-dose ...

African Journals Online (AJOL)

Blood specimens were collected from 8 people 18 days after they had been accidentally exposed to a 947,2 GBq iridium192 source during industrial application. The equivalent whole-body dose received at day 0 was estimated using a model based on quantitative and qualitative chromosome aberration analysis in ...

Review of the controversy on risks from low levels of radiation

International Nuclear Information System (INIS)

Higson, D.

2001-01-01

The need for regulation of low levels of radiation exposure, and the estimation of risks from such exposures, are based on the assumption that risk is proportional to dose without a threshold, the 'linear no-threshold (LNT) hypothesis'. This assumption is not supported by scientific data. There is no clear evidence of harm from low levels of exposure, up to at least 20 mSv (acute dose) or total dose rates of at least 50 mSv per year. Even allowing for reasonable extrapolation from radiation levels at which harmful effects have been observed, the LNT assumption should not be used to estimate risks from doses less than 100 mSv. Laboratory and epidemiological evidence, and evolutionary expectations of biological effects from low level radiation, suggest that beneficial health effects (sometimes called 'radiation hormesis') are at least as likely as harmful effects from such exposures. Controversy on this matter strikes at the basis of radiation protection practice

Biodistribution parameters and radiation absorbed dose estimates for radiolabeled human low density lipoprotein

International Nuclear Information System (INIS)

Hay, R.V.; Ryan, J.W.; Williams, K.A.; Atcher, R.W.; Brechbiel, M.W.; Gansow, O.A.; Fleming, R.M.; Stark, V.J.; Lathrop, K.A.; Harper, P.V.

1992-01-01

The authors propose a model to generate radiation absorbed dose estimates for radiolabeled low density lipoprotein (LDL), based upon eight studies of LDL biodistribution in three adult human subjects. Autologous plasma LDL was labeled with Tc-99m, I-123, or In-111 and injected intravenously. Biodistribution of each LDL derivative was monitored by quantitative analysis of scintigrams and direct counting of excreta and of serial blood samples. Assuming that transhepatic flux accounts for the majority of LDL clearance from the bloodstream, they obtained values of cumulated activity (A) and of mean dose per unit administered activity (D) for each study. In each case highest D values were calculated for liver, with mean doses of 5 rads estimated at injected activities of 27 mCi, 9 mCi, and 0.9 mCi for Tc-99m-LDL, I-123-LDL, and In-111-LDL, respectively

Lifetime radiation risks from low-dose rate radionuclides in beagles

International Nuclear Information System (INIS)

Goldman, M.; Rosenblatt, L.S.

1985-01-01

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

Low-Dose-Rate Brachytherapy Versus Cryotherapy in Low- and Intermediate-Risk Prostate Cancer.

Science.gov (United States)

Gestaut, Matthew M; Cai, Wendi; Vyas, Shilpa; Patel, Belur J; Hasan, Salman A; MunozMaldonado, Yolanda; Deb, Niloyjyoti; Swanson, Gregory

2017-05-01

Cryotherapy and brachytherapy are definitive local treatment options for low- to intermediate-risk prostate cancer. There are both prospective and retrospective data for brachytherapy, but the use of cryotherapy has been limited primarily to single-institution retrospective studies. Currently, no published evidence has compared low-dose-rate brachytherapy versus cryotherapy. Institutional review board approval was obtained to conduct a retrospective chart review of consecutive patients treated at our institution from 1990 to 2012. For inclusion, patients must have received a prostate cancer diagnosis and have been considered to have low- to intermediate-risk disease according to the National Comprehensive Cancer Network criteria. All patients received brachytherapy or cryotherapy treatment. Disease specifics and failure details were collected for all patients. Failure was defined as prostate-specific antigen nadir +2 ng/mL. A total of 359 patients were analyzed. The groups comprised 50 low-risk cryotherapy (LRC), 92 intermediate-risk cryotherapy (IRC), 133 low-risk brachytherapy (LRB), and 84 intermediate-risk brachytherapy (IRB) patients. The median prostate-specific antigen follow-up periods were 85.6 months (LRC), 59.2 months (IRC), 74.9 months (LRB), and 59.8 months (IRB). The 5-year biochemical progression-free survival (bPFS) rate was 57.9% in the cryotherapy group versus 89.6% in the brachytherapy group (Pcryotherapy for low- and intermediate-risk groups (Pcryotherapy patients was -35°C (range, -96°C to -6°C). Cryotherapy used a median of 2 freeze-thaw cycles (range, 2-4 freeze-thaw cycles). Results from this study suggest that cryotherapy is inferior to brachytherapy for patients with low- to intermediate-risk prostate cancer. Patient selection criteria for consideration of cryotherapy and brachytherapy are similar in terms of anesthesia candidacy. Therefore, cryotherapy would not be recommended as a first-line local therapy for this particular

Research on low radiation doses - A better understanding of low doses

International Nuclear Information System (INIS)

2016-01-01

Radiation doses below 100 mSv are called low doses. Epidemiological research on the health hazards of low doses are difficult to do because numerous pathologies, particularly cancer, appear lifelong for genetical or environmental causes without any link with irradiation and it is very difficult to identify the real cause of a cancer. Another concern is that the impact on human health is weak and are observed only after a long period after irradiation. These features make epidemiological studies cumbersome to implement since they require vast cohorts and a very long-term follow-up. The extrapolation of the effects of higher doses to the domain of low doses does not meet reality and it is why the European Union takes part into the financing of such research. In order to gain efficiency, scientists work together through various European networks among them: HLEG (High Level Expert Group On European Low Dose Risk Research) or MELODI (Multidisciplinary European Low Dose Initiative). Several programs are underway or have been recently launched: -) the impact of Cesium contamination on children's health (Epice program), -) the study of the impact of medical imaging on children, -) the study of the health of children living near nuclear facilities, -) the relationship between radon and lung cancer, -) the effect of occupational low radiation doses, -) the effect of uranium dissolved in water on living organisms (Envirhom program). (A.C.)

Low-dose aspirin and risk of intracranial bleeds: An observational study in UK general practice.

Science.gov (United States)

Cea Soriano, Lucía; Gaist, David; Soriano-Gabarró, Montse; Bromley, Susan; García Rodríguez, Luis A

2017-11-28

To quantify the risk of intracranial bleeds (ICBs) associated with new use of prophylactic low-dose aspirin using a population-based primary care database in the United Kingdom. A cohort of new users of low-dose aspirin (75-300 mg; n = 199,079) aged 40-84 years and a 1:1 matched cohort of nonusers of low-dose aspirin at baseline were followed (maximum 14 years, median 5.4 years) to identify incident cases of ICB, with validation by manual review of patient records or linkage to hospitalization data. Using 10,000 frequency-matched controls, adjusted rate ratios (RRs) with 95% confidence intervals (CIs) were calculated for current low-dose aspirin use (0-7 days before the index date [ICB date for cases, random date for controls]); reference group was never used. There were 1,611 cases of ICB (n = 743 for intracerebral hemorrhage [ICH], n = 483 for subdural hematoma [SDH], and n = 385 for subarachnoid hemorrhage [SAH]). RRs (95% CI) were 0.98 (0.84-1.13) for all ICB, 0.98 (0.80-1.20) for ICH, 1.23 (0.95-1.59) for SDH, and 0.77 (0.58-1.01) for SAH. No duration of use or dose-response association was apparent. RRs (95% CI) for ≥1 year of low-dose aspirin use were 0.90 (0.72-1.13) for ICH, 1.20 (0.91-1.57) for SDH, and 0.69 (0.50-0.94) for SAH. Low-dose aspirin is not associated with an increased risk of any type of ICB and is associated with a significantly decreased risk of SAH when used for ≥1 year. © 2017 American Academy of Neurology.

Cytogenetic Low-Dose Hyperradiosensitivity Is Observed in Human Peripheral Blood Lymphocytes

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Seth, Isheeta [Department of Biological Sciences, Wayne State University, Detroit, Michigan (United States); Joiner, Michael C. [Department of Radiation Oncology, Wayne State University, Detroit, Michigan (United States); Tucker, James D., E-mail: jtucker@biology.biosci.wayne.edu [Department of Biological Sciences, Wayne State University, Detroit, Michigan (United States)

2015-01-01

Purpose: The shape of the ionizing radiation response curve at very low doses has been the subject of considerable debate. Linear-no-threshold (LNT) models are widely used to estimate risks associated with low-dose exposures. However, the low-dose hyperradiosensitivity (HRS) phenomenon, in which cells are especially sensitive at low doses but then show increased radioresistance at higher doses, provides evidence of nonlinearity in the low-dose region. HRS is more prominent in the G2 phase of the cell cycle than in the G0/G1 or S phases. Here we provide the first cytogenetic mechanistic evidence of low-dose HRS in human peripheral blood lymphocytes using structural chromosomal aberrations. Methods and Materials: Human peripheral blood lymphocytes from 2 normal healthy female donors were acutely exposed to cobalt 60 γ rays in either G0 or G2 using closely spaced doses ranging from 0 to 1.5 Gy. Structural chromosomal aberrations were enumerated, and the slopes of the regression lines at low doses (0-0.4 Gy) were compared with doses of 0.5 Gy and above. Results: HRS was clearly evident in both donors for cells irradiated in G2. No HRS was observed in cells irradiated in G0. The radiation effect per unit dose was 2.5- to 3.5-fold higher for doses ≤0.4 Gy than for doses >0.5 Gy. Conclusions: These data provide the first cytogenetic evidence for the existence of HRS in human cells irradiated in G2 and suggest that LNT models may not always be optimal for making radiation risk assessments at low doses.

Methods to estimate the genetic risk

International Nuclear Information System (INIS)

Ehling, U.H.

1989-01-01

The estimation of the radiation-induced genetic risk to human populations is based on the extrapolation of results from animal experiments. Radiation-induced mutations are stochastic events. The probability of the event depends on the dose; the degree of the damage dose not. There are two main approaches in making genetic risk estimates. One of these, termed the direct method, expresses risk in terms of expected frequencies of genetic changes induced per unit dose. The other, referred to as the doubling dose method or the indirect method, expresses risk in relation to the observed incidence of genetic disorders now present in man. The advantage of the indirect method is that not only can Mendelian mutations be quantified, but also other types of genetic disorders. The disadvantages of the method are the uncertainties in determining the current incidence of genetic disorders in human and, in addition, the estimasion of the genetic component of congenital anomalies, anomalies expressed later and constitutional and degenerative diseases. Using the direct method we estimated that 20-50 dominant radiation-induced mutations would be expected in 19 000 offspring born to parents exposed in Hiroshima and Nagasaki, but only a small proportion of these mutants would have been detected with the techniques used for the population study. These methods were used to predict the genetic damage from the fallout of the reactor accident at Chernobyl in the vicinity of Southern Germany. The lack of knowledge for the interaction of chemicals with ionizing radiation and the discrepancy between the high safety standards for radiation protection and the low level of knowledge for the toxicological evaluation of chemical mutagens will be emphasized. (author)

Patient Doses and Risk Evaluation in Bone Mineral Densitometry

International Nuclear Information System (INIS)

Angelucci, M.; Borio, R.; Chiocchini, S.; Degli Esposti, P.; Dipilato, A.C.; Policani, G.

1999-01-01

The aim of this work was to evaluate the equipment dose to the organs and tissues and the effective dose of patients undergoing the most frequent examinations carried out in bone mineral densitometry (BMD): lumbar spine and femur. Experimental measurements of absorbed doses on a Rando phantom, allow comparison of the performances of three different photon emitter facilities. The comparison of the entrance and exit doses measured on a Rando phantom and on 50 female non-obese patients show that entrance doses on Rando can be used as 'diagnostic reference levels' for patients. A quantitative estimate of the stochastic risk due to BMD procedures was made: the results obtained show that the stochastic risk is very low and that the BMD is, at present, the most confirmed procedure for osteoporosis diagnosis and management. (author)

A Web-Based System for Bayesian Benchmark Dose Estimation.

Science.gov (United States)

Shao, Kan; Shapiro, Andrew J

2018-01-11

Benchmark dose (BMD) modeling is an important step in human health risk assessment and is used as the default approach to identify the point of departure for risk assessment. A probabilistic framework for dose-response assessment has been proposed and advocated by various institutions and organizations; therefore, a reliable tool is needed to provide distributional estimates for BMD and other important quantities in dose-response assessment. We developed an online system for Bayesian BMD (BBMD) estimation and compared results from this software with U.S. Environmental Protection Agency's (EPA's) Benchmark Dose Software (BMDS). The system is built on a Bayesian framework featuring the application of Markov chain Monte Carlo (MCMC) sampling for model parameter estimation and BMD calculation, which makes the BBMD system fundamentally different from the currently prevailing BMD software packages. In addition to estimating the traditional BMDs for dichotomous and continuous data, the developed system is also capable of computing model-averaged BMD estimates. A total of 518 dichotomous and 108 continuous data sets extracted from the U.S. EPA's Integrated Risk Information System (IRIS) database (and similar databases) were used as testing data to compare the estimates from the BBMD and BMDS programs. The results suggest that the BBMD system may outperform the BMDS program in a number of aspects, including fewer failed BMD and BMDL calculations and estimates. The BBMD system is a useful alternative tool for estimating BMD with additional functionalities for BMD analysis based on most recent research. Most importantly, the BBMD has the potential to incorporate prior information to make dose-response modeling more reliable and can provide distributional estimates for important quantities in dose-response assessment, which greatly facilitates the current trend for probabilistic risk assessment. https://doi.org/10.1289/EHP1289.

beta. and. gamma. -comparative dose estimates on Enewetak Atoll

Energy Technology Data Exchange (ETDEWEB)

Crase, K.W.; Gudiksen, P.H.; Robison, W.L. (California Univ., Livermore (USA). Lawrence Livermore National Lab.)

1982-05-01

Enewetak Atoll in the Pacific is used for atmospheric testing of U.S. nuclear weapons. Beta dose and ..gamma..-ray exposure measurements were made on two islands of the Enewetak Atoll during July-August 1976 to determine the ..beta.. and low energy ..gamma..-contribution to the total external radiation doses to the returning Marshallese. Measurements were made at numerous locations with thermoluminescent dosimeters (TLD), pressurized ionization chambers, portable NaI detectors, and thin-window pancake GM probes. Results of the TLD measurements with and without a ..beta..-attenuator indicate that approx. 29% of the total dose rate at 1 m in air is due to ..beta..- or low energy ..gamma..-contribution. The contribution at any particular site, however, is reduced by vegetation. Integral 30-yr external shallow dose estimates for future inhabitants were made and compared with external dose estimates of a previous large scale radiological survey. Integral 30-yr shallow external dose estimates are 25-50% higher than whole body estimates. Due to the low penetrating ability of the ..beta..'s or low energy ..gamma..'s, however, several remedial actions can be taken to reduce the shallow dose contribution to the total external dose.

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)

Di Giorgio, Marina; Zaretzky, A.

2010-01-01

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) [es

Contamination and cancers: low-dose risks and standards of radioprotection

International Nuclear Information System (INIS)

Vignes, S.

1980-01-01

Irradiation of the population due to the running of nuclear power stations represents less than 1% of the natural radioactivity today, and should amount to 3% at most by the year 2 000. The main effects of ionizing radiations are reviewed and their undetectability below 100 rems is underlined. Thus the evaluation of low-dose risks can only be speculative and the cautions hypothesis adopted is that of a linear relationship between dose and effect, together with the absence of threshold. According to calculations the worker, supposedly exposed to 500 mrem a year between ages 18 and 65, would run a 22.2% instead of the normal 22% risk of dying of cancer. As for the population, the risk would increase by only 1 per 10 000 in the year 2 000. This means that no other mutagenic and carcinogenic agent is as well regulated as radioactive pollution and efforts directed at a better control of harmful chemicals, for instance, are only taking an example from the ruling on radioprotection [fr

Estimates of bias and uncertainty in recorded external dose

International Nuclear Information System (INIS)

Fix, J.J.; Gilbert, E.S.; Baumgartner, W.V.

1994-10-01

A study is underway to develop an approach to quantify bias and uncertainty in recorded dose estimates for workers at the Hanford Site based on personnel dosimeter results. This paper focuses on selected experimental studies conducted to better define response characteristics of Hanford dosimeters. The study is more extensive than the experimental studies presented in this paper and includes detailed consideration and evaluation of other sources of bias and uncertainty. Hanford worker dose estimates are used in epidemiologic studies of nuclear workers. A major objective of these studies is to provide a direct assessment of the carcinogenic risk of exposure to ionizing radiation at low doses and dose rates. Considerations of bias and uncertainty in the recorded dose estimates are important in the conduct of this work. The method developed for use with Hanford workers can be considered an elaboration of the approach used to quantify bias and uncertainty in estimated doses for personnel exposed to radiation as a result of atmospheric testing of nuclear weapons between 1945 and 1962. This approach was first developed by a National Research Council (NRC) committee examining uncertainty in recorded film badge doses during atmospheric tests (NRC 1989). It involved quantifying both bias and uncertainty from three sources (i.e., laboratory, radiological, and environmental) and then combining them to obtain an overall assessment. Sources of uncertainty have been evaluated for each of three specific Hanford dosimetry systems (i.e., the Hanford two-element film dosimeter, 1944-1956; the Hanford multi-element film dosimeter, 1957-1971; and the Hanford multi-element TLD, 1972-1993) used to estimate personnel dose throughout the history of Hanford operations. Laboratory, radiological, and environmental sources of bias and uncertainty have been estimated based on historical documentation and, for angular response, on selected laboratory measurements

Evaluation of Low- Versus High-dose Valganciclovir for Prevention of Cytomegalovirus Disease in High-risk Renal Transplant Recipients.

Science.gov (United States)

Gabardi, Steven; Asipenko, Natalya; Fleming, James; Lor, Kevin; McDevitt-Potter, Lisa; Mohammed, Anisa; Rogers, Christin; Tichy, Eric M; Weng, Renee; Lee, Ruth-Ann

2015-07-01

Despite proven efficacy of prolonged cytomegalovirus (CMV) prophylaxis using valganciclovir 900 mg/day, some centers use 450 mg/day due to reported success and cost savings. This multicenter, retrospective study compared the efficacy and safety of 6 months of low-dose versus high-dose valganciclovir prophylaxis in high-risk, donor-positive/recipient-negative, renal transplant recipients (RTR). Two hundred thirty-seven high-risk RTR (low-dose group = valganciclovir 450 mg/day [n = 130]; high-dose group = valganciclovir 900 mg/day [n = s7]) were evaluated for 1-year CMV disease prevalence. Breakthrough CMV, resistant CMV, biopsy-proven acute rejection (BPAR), graft loss, opportunistic infections (OI), new-onset diabetes after transplantation (NODAT), premature valganciclovir discontinuation, renal function and myelosuppression were also assessed. Patient demographics and transplant characteristics were comparable. Induction and maintenance immunosuppression were similar, except for more early steroid withdrawal in the high-dose group. Similar proportions of patients developed CMV disease (14.6% vs 24.3%; P = 0.068); however, controlling CMV risk factor differences through multivariate logistic regression revealed significantly lower CMV disease in the low-dose group (P = 0.02; odds ratio, 0.432, 95% confidence interval, 0.211-0.887). Breakthrough and resistant CMV occurred at similar frequencies. There was no difference in renal function or rates of biopsy-proven acute rejection, graft loss, opportunistic infections, or new-onset diabetes after transplantation. The high-dose group had significantly lower mean white blood cell counts at months 5 and 6; however, premature valganciclovir discontinuation rates were similar. Low-dose and high-dose valganciclovir regimens provide similar efficacy in preventing CMV disease in high-risk RTR, with a reduced incidence of leukopenia associated with the low-dose regimen and no difference in resistant CMV. Low-dose valganciclovir

Risk management or mind control? Possible messages in the report by the working group on the risk management of low-dose exposures

International Nuclear Information System (INIS)

Onai, Takayuki; Shirabe, Masashi

2012-01-01

Fukushima accident discharged a large amount of radioactive materials to the air and brought about a long-term low-dose radiation exposure risk in contaminated area. In December 2011 the government working group (WG) on the risk management of low-dose radiation exposure issued the report on subjects: (1) health effects from annual radiation exposure of 20 mSv, (2) special consideration necessary for children and pregnant women and (3) proper way communicating citizens on radioactive materials and radiation doses in relation to health risks from low-dose radiation exposure. This article recommended making radiation protection strategies based on discussions among experts, government and citizens in consideration of “uncertainty” of scientific knowledge, and it criticized the WG's report mainly in the following respects. 1) The report mixed evacuation order level and ICRP's reference level in its discussion on “20 mSv”. 2) It was over-optimistic and frequently misleading on health risks of low-dose radiation. For example, it sometimes discussed the risks employing data and knowledge against recommendations of international authorities like UNSCEAR and ICRP. 3) It regarded Fukushima residents’ anxieties and stresses to be controlled as the only source of health risks. This attitude offered a counterpoint to UNSCEAR's deliberate attitude to “radiophobia”. 4) Against the spirit of ICRP Publ.111, only experts of WG made decisions about radiation protection in the absence of stakeholders. As its result, 5) risk communication recommended in the report was not interactive, in fact, based on “deficit model” of science communication. (author)

Health effects of low doses at low dose rates: dose-response relationship modeling in a cohort of workers of the nuclear industry; Effets sanitaires des faibles doses a faibles debits de dose: modelisation de la relation dose-reponse dans une cohorte de travailleurs du nucleaire

Energy Technology Data Exchange (ETDEWEB)

Metz-Flamant, Camille

2011-09-19

exposure. Our study finds a risk of leukemia associated with chronic external exposure and allows taking into account modifying factors of this relation. Additional follow-up allows to improve the precision of the estimated dose-response relationship. A combined analysis including the present cohort and other nuclear cohorts could quantify more precisely the risks associated with low doses at low dose rates, in order to validate current underlying hypotheses of the radiation protection system. (author)

Estimating radiation risk induced by CT screening for Korean population

Science.gov (United States)

Yang, Won Seok; Yang, Hye Jeong; Min, Byung In

2017-02-01

The purposes of this study are to estimate the radiation risks induced by chest/abdomen computed tomography (CT) screening for healthcare and to determine the cancer risk level of the Korean population compared to other populations. We used an ImPACT CT Patient Dosimetry Calculator to compute the organ effective dose induced by CT screening (chest, low-dose chest, abdomen/pelvis, and chest/abdomen/pelvis CT). A risk model was applied using principles based on the BEIR VII Report in order to estimate the lifetime attributable risk (LAR) using the Korean Life Table 2010. In addition, several countries including Hong Kong, the United States (U.S.), and the United Kingdom, were selected for comparison. Herein, each population exposed radiation dose of 100 mSv was classified according to country, gender and age. For each CT screening the total organ effective dose calculated by ImPACT was 6.2, 1.5, 5.2 and 11.4 mSv, respectively. In the case of Korean female LAR, it was similar to Hong Kong female but lower than those of U.S. and U.K. females, except for those in their twenties. The LAR of Korean males was the highest for all types of CT screening. However, the difference of the risk level was negligible because of the quite low value.

Validity of the linear no-threshold theory of radiation carcinogenesis at low doses

International Nuclear Information System (INIS)

Cohen, B.L.

1999-01-01

A great deal is known about the cancer risk of high radiation doses from studies of Japanese A-bomb survivors, patients exposed for medical therapy, occupational exposures, etc. But the vast majority of important applications deal with much lower doses, usually accumulated at much lower dose rates, referred to as 'low-level radiation' (LLR). Conventionally, the cancer risk from LLR has been estimated by the use of linear no-threshold theory (LNT). For example, it is assumed that the cancer risk from 0 01 Sr (100 mrem) of dose is 0 01 times the risk from 1 Sv (100 rem). In recent years, the former risk estimates have often been reduced by a 'dose and dose rate reduction factor', which is taken to be a factor of 2. But otherwise, the LNT is frequently used for doses as low as one hundred-thousandth of those for which there is direct evidence of cancer induction by radiation. It is the origin of the commonly used expression 'no level of radiation is safe' and the consequent public fear of LLR. The importance of this use of the LNT can not be exaggerated and is used in many applications in the nuclear industry. The LNT paradigm has also been carried over to chemical carcinogens, leading to severe restrictions on use of cleaning fluids, organic chemicals, pesticides, etc. If the LNT were abandoned for radiation, it would probably also be abandoned for chemical carcinogens. In view of these facts, it is important to consider the validity of the LNT. That is the purpose of this paper. (author)

Estimation of risks from medical irradiation

International Nuclear Information System (INIS)

Persson, B.R.R.

1983-01-01

This paper discuss various concepts of quantifying risks from medical irradiation. The expected individual risk from specific medical examination can be derived by estimation the dose-equivalent in different organs and tissues and apply the risk factors recommended for these tissues. A more practical way is to estimate or measure the energy imparted which has been found to correlate quite well with the total risk derived by summing up the risks for the involved tissues. The effective dose-equivalent concept can be used to derive the collective effective dose-equivalent in a population in order to compare the contribution from medical exposure with the contribution from other sources of irradiation in the society. In many countries it is thus shown that medical exposures gives the largest man-made contribution to the population dose

The assessment of risks from exposure to low-levels of ionizing radiation

International Nuclear Information System (INIS)

Gilbert, E.S.

1992-06-01

This report is concerned with risk assessments for human populations receiving low level radiation doses; workers routinely exposed to radiation, Japanese victims of nuclear bombs, and the general public are all considered. Topics covered include risk estimates for cancer, mortality rates, risk estimates for nuclear site workers, and dosimetry

Low-Dose-Rate Brachytherapy Versus Cryotherapy in Low- and Intermediate-Risk Prostate Cancer

International Nuclear Information System (INIS)

Gestaut, Matthew M.; Cai, Wendi; Vyas, Shilpa; Patel, Belur J.; Hasan, Salman A.; MunozMaldonado, Yolanda; Deb, Niloyjyoti; Swanson, Gregory

2017-01-01

Purpose: Cryotherapy and brachytherapy are definitive local treatment options for low- to intermediate-risk prostate cancer. There are both prospective and retrospective data for brachytherapy, but the use of cryotherapy has been limited primarily to single-institution retrospective studies. Currently, no published evidence has compared low-dose-rate brachytherapy versus cryotherapy. Methods and Materials: Institutional review board approval was obtained to conduct a retrospective chart review of consecutive patients treated at our institution from 1990 to 2012. For inclusion, patients must have received a prostate cancer diagnosis and have been considered to have low- to intermediate-risk disease according to the National Comprehensive Cancer Network criteria. All patients received brachytherapy or cryotherapy treatment. Disease specifics and failure details were collected for all patients. Failure was defined as prostate-specific antigen nadir +2 ng/mL. Results: A total of 359 patients were analyzed. The groups comprised 50 low-risk cryotherapy (LRC), 92 intermediate-risk cryotherapy (IRC), 133 low-risk brachytherapy (LRB), and 84 intermediate-risk brachytherapy (IRB) patients. The median prostate-specific antigen follow-up periods were 85.6 months (LRC), 59.2 months (IRC), 74.9 months (LRB), and 59.8 months (IRB). The 5-year biochemical progression–free survival (bPFS) rate was 57.9% in the cryotherapy group versus 89.6% in the brachytherapy group (P<.0001). The 5-year bPFS rate was 70.0% (LRC), 51.4% (IRC), 89.4% (LRB), and 89.7% (IRB). The bPFS rate was significantly different between brachytherapy and cryotherapy for low- and intermediate-risk groups (P<.05). The mean nadir temperature reached for cryotherapy patients was −35°C (range, −96°C to −6°C). Cryotherapy used a median of 2 freeze-thaw cycles (range, 2-4 freeze-thaw cycles). Conclusions: Results from this study suggest that cryotherapy is inferior to brachytherapy for patients with

Low-Dose-Rate Brachytherapy Versus Cryotherapy in Low- and Intermediate-Risk Prostate Cancer

Energy Technology Data Exchange (ETDEWEB)

Gestaut, Matthew M., E-mail: Matthew.Gestaut@BSWHealth.org [Department of Radiation Oncology, Baylor Scott and White Memorial Hospital, Texas A& M University School of Medicine, Temple, Texas (United States); Cai, Wendi [Department of Biostatistics, Baylor Scott and White Health, Temple, Texas (United States); Vyas, Shilpa [Department of Radiation Oncology, Swedish Cancer Institute, Seattle, Washington (United States); Patel, Belur J. [Department of Urology, Baylor Scott and White Memorial Hospital, Texas A& M University School of Medicine, Temple, Texas (United States); Hasan, Salman A. [Department of Radiation Oncology, Baylor Scott and White Memorial Hospital, Texas A& M University School of Medicine, Temple, Texas (United States); MunozMaldonado, Yolanda [Department of Biostatistics, Baylor Scott and White Health, Temple, Texas (United States); Deb, Niloyjyoti; Swanson, Gregory [Department of Radiation Oncology, Baylor Scott and White Memorial Hospital, Texas A& M University School of Medicine, Temple, Texas (United States)

2017-05-01

Purpose: Cryotherapy and brachytherapy are definitive local treatment options for low- to intermediate-risk prostate cancer. There are both prospective and retrospective data for brachytherapy, but the use of cryotherapy has been limited primarily to single-institution retrospective studies. Currently, no published evidence has compared low-dose-rate brachytherapy versus cryotherapy. Methods and Materials: Institutional review board approval was obtained to conduct a retrospective chart review of consecutive patients treated at our institution from 1990 to 2012. For inclusion, patients must have received a prostate cancer diagnosis and have been considered to have low- to intermediate-risk disease according to the National Comprehensive Cancer Network criteria. All patients received brachytherapy or cryotherapy treatment. Disease specifics and failure details were collected for all patients. Failure was defined as prostate-specific antigen nadir +2 ng/mL. Results: A total of 359 patients were analyzed. The groups comprised 50 low-risk cryotherapy (LRC), 92 intermediate-risk cryotherapy (IRC), 133 low-risk brachytherapy (LRB), and 84 intermediate-risk brachytherapy (IRB) patients. The median prostate-specific antigen follow-up periods were 85.6 months (LRC), 59.2 months (IRC), 74.9 months (LRB), and 59.8 months (IRB). The 5-year biochemical progression–free survival (bPFS) rate was 57.9% in the cryotherapy group versus 89.6% in the brachytherapy group (P<.0001). The 5-year bPFS rate was 70.0% (LRC), 51.4% (IRC), 89.4% (LRB), and 89.7% (IRB). The bPFS rate was significantly different between brachytherapy and cryotherapy for low- and intermediate-risk groups (P<.05). The mean nadir temperature reached for cryotherapy patients was −35°C (range, −96°C to −6°C). Cryotherapy used a median of 2 freeze-thaw cycles (range, 2-4 freeze-thaw cycles). Conclusions: Results from this study suggest that cryotherapy is inferior to brachytherapy for patients with

Cancer risk estimation from the A-bomb survivors

International Nuclear Information System (INIS)

Pierce, D.A.; Vaeth, M.

1989-10-01

Generalizations regarding radiogenic cancer risks from the A-bomb survivor data of the Radiation Effects Research Foundation involve a large number of well-identified uncertainties and approximations. These include extrapolation to low doses and dose rates, projections in time, sampling variation, the quality of the data, extrapolation to other populations, and the use of simplifying conventions. This paper discusses some of these issues, with emphasis on the first three. Results are given regarding the maximum 'linear-quadratic' curvature consistent with these data, taking into account uncertainties in individual exposure estimates. Discussion is given regarding use of relative risk models and projection of lifetime risks, emphasizing results for those who were old enough at exposure to have been followed up for a major part of their lives by now, and stressing the speculative aspects of conclusions about those exposed as children. Combining these results, and brief discussion of other uncertainties itemized above, comment is made on the evolution of risk estimates over the past 15 years. (author)

Biological Effects of Low-Dose Exposure

CERN Document Server

Komochkov, M M

2000-01-01

On the basis of the two-protection reaction model an analysis of stochastic radiobiological effects of low-dose exposure of different biological objects has been carried out. The stochastic effects are the results published in the last decade: epidemiological studies of human cancer mortality, the yield of thymocyte apoptosis of mice and different types of chromosomal aberrations. The results of the analysis show that as dependent upon the nature of biological object, spontanous effect, exposure conditions and radiation type one or another form dose - effect relationship is realized: downwards concave, near to linear and upwards concave with the effect of hormesis included. This result testifies to the incomplete conformity of studied effects of 1990 ICRP recomendations based on the linear no-threshold hypothesis about dose - effect relationship. Because of this the methodology of radiation risk estimation recomended by ICRP needs more precisian and such quantity as collective dose ought to be classified into...

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

International Nuclear Information System (INIS)

Nomura, Takaharu

2008-01-01

β-cells against superoxide generated by glycation reaction evoked by high glucose environment. Continuous irradiation at 0.63 mGy/hr from 28 days of age elongates life span, and recovers splenic inflammatory response in Klotho-mice bearing ageing syndrome. The radiation increases anti-oxidants in liver, implicating the prevention of ageing through the suppression of cellular oxidative damages. Our results suggest that low dose/low dose-rate radiation effectively ameliorates diseases related to reactive oxygen species, and elongates life span of animals, at least in part through the stimulation of protective responses against oxidative stress. These findings are important not only for clinical use of low dose/low dose-rate radiation for human diseases, but also for non-cancerous risk estimation at dose and dose rate range argued in legal restrictions. (author)

Low-Dose Aspirin Discontinuation and Risk of Cardiovascular Events: A Swedish Nationwide, Population-Based Cohort Study.

Science.gov (United States)

Sundström, Johan; Hedberg, Jakob; Thuresson, Marcus; Aarskog, Pernilla; Johannesen, Kasper Munk; Oldgren, Jonas

2017-09-26

There are increasing concerns about risks associated with aspirin discontinuation in the absence of major surgery or bleeding. We investigated whether long-term low-dose aspirin discontinuation and treatment gaps increase the risk of cardiovascular events. We performed a cohort study of 601 527 users of low-dose aspirin for primary or secondary prevention in the Swedish prescription register between 2005 and 2009 who were >40 years of age, were free from previous cancer, and had ≥80% adherence during the first observed year of treatment. Cardiovascular events were identified with the Swedish inpatient and cause-of-death registers. The first 3 months after a major bleeding or surgical procedure were excluded from the time at risk. During a median of 3.0 years of follow-up, 62 690 cardiovascular events occurred. Patients who discontinued aspirin had a higher rate of cardiovascular events than those who continued (multivariable-adjusted hazard ratio, 1.37; 95% confidence interval, 1.34-1.41), corresponding to an additional cardiovascular event observed per year in 1 of every 74 patients who discontinue aspirin. The risk increased shortly after discontinuation and did not appear to diminish over time. In long-term users, discontinuation of low-dose aspirin in the absence of major surgery or bleeding was associated with a >30% increased risk of cardiovascular events. Adherence to low-dose aspirin treatment in the absence of major surgery or bleeding is likely an important treatment goal. © 2017 American Heart Association, Inc.

Donor-specific cell-based assays in studying sensitivity to low-dose radiation: a population-based perspective

Directory of Open Access Journals (Sweden)

Dora eIl'yasova

2014-11-01

Full Text Available Currently, a linear no-threshold model is used to estimate health risks associated with exposure to low-dose radiation, a prevalent exposure in the general population, because the direct estimation from epidemiological studies suffers from uncertainty. This model has been criticized based on unique biology of low-dose radiation. Whether the departure from linearity is toward increased or decreased risk is intensely debated. We present an approach based on individual radiosensitivity testing and discuss how individual radiosensitivity can be assessed with the goal to develop a quantifiable measure of cellular response that can be conducted via high-throughput population testing.

Hormesis: from marginalization to mainstream A case for hormesis as the default dose-response model in risk assessment

International Nuclear Information System (INIS)

Calabrese, Edward J.

2004-01-01

The paper provides an account of how the hormetic dose response has emerged in recent years as a serious dose-response model in toxicology and risk assessment after decades of extreme marginalization. In addition to providing the toxicological basis of this dose-response revival, the paper reexamines the concept of a default dose model in toxicology and risk assessment and makes the argument that the hormetic model satisfies criteria (e.g., generalizability, frequency, application to risk assessment endpoints, false positive/negative potential, requirements for hazard assessment, reliability of estimating risks, capacity for validation of risk estimates, public health implications of risk estimates) for such a default model better than its chief competitors, the threshold and linear at low dose models. The selection of the hormetic model as the default model in risk assessment for noncarcinogens and specifically for carcinogens would have a profound impact on the practice of risk assessment and its societal implications

Risk of Low Dose/Low Dose Rate Ionizing Radiation to Humans Symposium Annual Meeting of the Environmental Mutagen Society: Agenda and Abstracts

Energy Technology Data Exchange (ETDEWEB)

Veigl, Martina L. [Environmental Mutagen Society (EMS), Reston, VA (United States); Case Western Reserve Univ., Cleveland, OH (United States). Case Comprehensive Cancer Center; Morgan, William F. [Univ. of Maryland, College Park, MD (United States); Schwartz, Jeffrey L. [Univ. of Washington, Seattle, WA (United States)

2009-11-11

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

Dose-stress synergism in cancer risk assessment

International Nuclear Information System (INIS)

Pop-Jordanova, N.; Pop-Jordanov, J.

2001-01-01

Our hypothesis is that the relatively low risk of cancer or leukaemia from depleted uranium, as predicted by the World Health Organization and the International Atomic Energy Agency, is a result of neglecting the synergism between physico-chemical agents and psychological stress agents (here shortly denoted as dose-stress synergism). We use the modified risk assessment model that comprises a psycho-somatic extension, originally developed by us for assessing the risks of energy sources. Our preliminary meta-analysis of animal and human studies on cancers confirmed the existence of stress effects, including the amplifying synergism. Consequently, the psychological stress can increase the probability of even small toxic chemical or ionizing radiation exposure to produce malignancy. Such dose-stress synergism might influence the health risks among military personnel and the residents in the highly stressful environment in the Balkans. Further investigation is needed to estimate the order of magnitude of these combined effects in particular circumstances. (Original)

Radiation dose in cardiac SPECT/CT: An estimation of SSDE and effective dose

International Nuclear Information System (INIS)

Abdollahi, Hamid; Shiri, Isaac; Salimi, Yazdan; Sarebani, Maghsoud; Mehdinia, Reza; Deevband, Mohammad Reza; Mahdavi, Seied Rabi; Sohrabi, Ahmad; Bitarafan-Rajabi, Ahmad

2016-01-01

Aims: The dose levels for Computed Tomography (CT) localization and attenuation correction of Single Photon Emission Computed Tomography (SPECT) are limited and reported as Volume Computed Tomography Dose Index (CTDIvol) and Dose-Length Product (DLP). This work presents CT dose estimation from Cardiac SPECT/CT based on new American Association of Physicists in Medicine (AAPM) Size Specific Dose Estimation (SSDE) parameter, effective dose, organ doses and also emission dose from nuclear issue. Material and methods: Myocardial perfusion SPECT/CT for 509 patients was included in the study. SSDE, effective dose and organ dose were calculated using AAPM guideline and Impact-Dose software. Data were analyzed using R and SPSS statistical software. Spearman-Pearson correlation test and linear regression models were used for finding correlations and relationships among parameters. Results: The mean CTDIvol was 1.34 mGy ± 0.19 and the mean SSDE was 1.7 mGy ± 0.16. The mean ± SD of effective dose from emission, CT and total dose were 11.5 ± 1.4, 0.49 ± 0.11 and 12.67 ± 1.73 (mSv) respectively. The mean ± SD of effective dose from emission, CT and total dose were 11.5 ± 1.4, 0.49 ± 0.11 and 12.67 ± 1.73 (mSv) respectively. The spearman test showed that correlation between body size and organ doses is significant except thyroid and red bone marrow. CTDIvol was strongly dependent on patient size, but SSDE was not. Emission dose was strongly dependent on patient weight, but its dependency was lower to effective diameter. Conclusion: The dose parameters including CTDIvol, DLP, SSDE, effective dose values reported here are very low and below the reference level. This data suggest that appropriate CT acquisition parameters in SPECT/CT localization and attenuation correction are very beneficial for patients and lowering cancer risks.

Radiation dose in cardiac SPECT/CT: An estimation of SSDE and effective dose

Energy Technology Data Exchange (ETDEWEB)

Abdollahi, Hamid, E-mail: Hamid_rbp@yahoo.com [Department of Medical Physics, School of Medicine, Iran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Shiri, Isaac [Department of Medical Physics, School of Medicine, Iran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Salimi, Yazdan [Biomedical Engineering and Medical Physics Department, Faculty of Medicine, Shahid Beheshti University of Medical Sciences, Tehran (Iran, Islamic Republic of); Sarebani, Maghsoud; Mehdinia, Reza [Department of Medical Physics, School of Medicine, Iran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Deevband, Mohammad Reza [Biomedical Engineering and Medical Physics Department, Faculty of Medicine, Shahid Beheshti University of Medical Sciences, Tehran (Iran, Islamic Republic of); Mahdavi, Seied Rabi [Department of Medical Physics, School of Medicine, Iran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Radiation Biology Research Center, Iran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Sohrabi, Ahmad [Department of Biostatistics, School of Public Health, Iran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Bitarafan-Rajabi, Ahmad, E-mail: bitarafan@hotmail.com [Department of Medical Physics, School of Medicine, Iran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Department of Nuclear Medicine, Rajaei Cardiovascular, Medical and Research Center, Iran University of Medical Sciences, Tehran (Iran, Islamic Republic of)

2016-12-15

Aims: The dose levels for Computed Tomography (CT) localization and attenuation correction of Single Photon Emission Computed Tomography (SPECT) are limited and reported as Volume Computed Tomography Dose Index (CTDIvol) and Dose-Length Product (DLP). This work presents CT dose estimation from Cardiac SPECT/CT based on new American Association of Physicists in Medicine (AAPM) Size Specific Dose Estimation (SSDE) parameter, effective dose, organ doses and also emission dose from nuclear issue. Material and methods: Myocardial perfusion SPECT/CT for 509 patients was included in the study. SSDE, effective dose and organ dose were calculated using AAPM guideline and Impact-Dose software. Data were analyzed using R and SPSS statistical software. Spearman-Pearson correlation test and linear regression models were used for finding correlations and relationships among parameters. Results: The mean CTDIvol was 1.34 mGy ± 0.19 and the mean SSDE was 1.7 mGy ± 0.16. The mean ± SD of effective dose from emission, CT and total dose were 11.5 ± 1.4, 0.49 ± 0.11 and 12.67 ± 1.73 (mSv) respectively. The mean ± SD of effective dose from emission, CT and total dose were 11.5 ± 1.4, 0.49 ± 0.11 and 12.67 ± 1.73 (mSv) respectively. The spearman test showed that correlation between body size and organ doses is significant except thyroid and red bone marrow. CTDIvol was strongly dependent on patient size, but SSDE was not. Emission dose was strongly dependent on patient weight, but its dependency was lower to effective diameter. Conclusion: The dose parameters including CTDIvol, DLP, SSDE, effective dose values reported here are very low and below the reference level. This data suggest that appropriate CT acquisition parameters in SPECT/CT localization and attenuation correction are very beneficial for patients and lowering cancer risks.

Uncertainties in fatal cancer risk estimates used in radiation protection

International Nuclear Information System (INIS)

Kai, Michiaki

1999-01-01

Although ICRP and NCRP had not described the details of uncertainties in cancer risk estimates in radiation protection, NCRP, in 1997, firstly reported the results of uncertainty analysis (NCRP No.126) and which is summarized in this paper. The NCRP report pointed out that there are following five factors which uncertainty possessing: uncertainty in epidemiological studies, in dose assessment, in transforming the estimates to risk assessment, in risk prediction and in extrapolation to the low dose/dose rate. These individual factors were analyzed statistically to obtain the relationship between the probability of cancer death in the US population and life time risk coefficient (% per Sv), which showed that, for the latter, the mean value was 3.99 x 10 -2 /Sv, median, 3.38 x 10 -2 /Sv, GSD (geometrical standard deviation), 1.83 x 10 -2 /Sv and 95% confidential limit, 1.2-8.84 x 10 -2 /Sv. The mean value was smaller than that of ICRP recommendation (5 x 10 -2 /Sv), indicating that the value has the uncertainty factor of 2.5-3. Moreover, the most important factor was shown to be the uncertainty in DDREF (dose/dose rate reduction factor). (K.H.)

Estimation of pneumonitis risk in three-dimensional treatment planning using dose-volume histogram analysis

International Nuclear Information System (INIS)

Oetzel, Dieter; Schraube, Peter; Hensley, Frank; Sroka-Perez, Gabriele; Menke, Markus; Flentje, Michael

1995-01-01

Purpose: Investigations to study correlations between the estimations of biophysical models in three dimensional (3D) treatment planning and clinical observations are scarce. The development of clinically symptomatic pneumonitis in the radiotherapy of thoracic malignomas was chosen to test the predictive power of Lyman's normal tissue complication probability (NTCP) model for the assessment of side effects for nonuniform irradiation. Methods and Materials: In a retrospective analysis individual computed-tomography-based 3D dose distributions of a random sample of (46(20)) patients with lung/esophageal cancer were reconstructed. All patients received tumor doses between 50 and 60 Gy in a conventional treatment schedule. Biological isoeffective dose-volume histograms (DVHs) were used for the calculation of complication probabilities after applying Lyman's and Kutcher's DVH-reduction algorithm. Lung dose statistics were performed for single lung (involved ipsilateral and contralateral) and for the lung as a paired organ. Results: In the lung cancer group, about 20% of the patients (9 out of 46) developed pneumonitis 3-12 (median 7.5) weeks after completion of radiotherapy. For the majority of these lung cancer patients, the involved ipsilateral lung received a much higher dose than the contralateral lung, and the pneumonitis patients had on average a higher lung exposure with a doubling of the predicted complication risk (38% vs. 20%). The lower lung exposure for the esophagus patients resulted in a mean lung dose of 13.2 Gy (lung cancer: 20.5 Gy) averaged over all patients in correlation with an almost zero complication risk and only one observed case of pneumonitis (1 out of 20). To compare the pneumonitis risk estimations with observed complication rates, the patients were ranked into bins of mean ipsilateral lung dose. Particularly, in the bins with the highest patient numbers, a good correlation was achieved. Agreement was not reached for the lung functioning as

Responses of epithelial cells to low and very low doses of low let radiation

International Nuclear Information System (INIS)

Mothersill, Carmel; Seymour, Colin

2003-01-01

Recent advances in our knowledge of the biological effects of low doses of ionizing radiation have shown unexpected phenomena. These vary in the endpoint used to detect them and in the dose range examined but all occur as high-frequency events in cell populations. They include: 1. a 'bystander effect' which can be demonstrated at low doses as a transferable.factor(s) causing radiobiological effects in unexposed cells, 2. an assortment of delayed effects' occurring in progeny of cells exposed to low doses, 3. Low-dose Hypersensitivity (HRS) and Increased radioresistance (IRR) which can collectively be demonstrated as a change in the dose-effect relationship, occurring around 0.5-1 Gy of low LET radiation and 4. adaptive responses where cells exposed to very low doses followed by higher doses, exhibit an induced relatively resistant response to the second dose. In all cases, the effect of very low doses is greater than would be predicted by extrapolation of high dose data and is inconsistent with conventional DNA break/repair-based radiobiology. In practical risk assessment terms, the relative importance of the effects are high at low doses where they dominate the response, and small at high doses. This paper reviews these assorted phenomena and in particular seeks to explore whether related or distinct mechanisms underlie these various effects Understanding the mechanistic basis of these phenomena may suggest new approaches to controlling death or survival sectoring at low radiation doses. The key question is whether these low dose phenomena necessitate a new approach to risk assessment. (author)

beta- and gamma-Comparative dose estimates on Eniwetok Atoll

Energy Technology Data Exchange (ETDEWEB)

Crase, K.W.; Gudiksen, P.H.; Robison, W.L.

1982-05-01

Eniwetok Atoll is one of the Pacific atolls used for atmospheric testing of U.S. nuclear weapons. Beta dose and gamma-ray exposure measurements were made on two islands of the Eniwetok Atoll during July-August 1976 to determine the beta and low energy gamma-contribution to the total external radiation doses to the returning Marshallese. Measurements were made at numerous locations with thermoluminescent dosimeters (TLD), pressurized ionization chambers, portable NaI detectors, and thin-window pancake GM probes. Results of the TLD measurements with and without a beta-attenuator indicate that approx. 29% of the total dose rate at 1 m in air is due to beta- or low energy gamma-contribution. The contribution at any particular site, however, is somewhat dependent on ground cover, since a minimal amount of vegetation will reduce it significantly from that over bare soil, but thick stands of vegetation have little effect on any further reductions. Integral 30-yr external shallow dose estimates for future inhabitants were made and compared with external dose estimates of a previous large scale radiological survey (En73). Integral 30-yr shallow external dose estimates are 25-50% higher than whole body estimates. Due to the low penetrating ability of the beta's or low energy gamma's, however, several remedial actions can be taken to reduce the shallow dose contribution to the total external dose.

Medical effects of low doses of ionising radiation

International Nuclear Information System (INIS)

Coggle, J.E.

1990-01-01

Ionising radiation is genotoxic and causes biological effects via a chain of events involving DNA strand breaks and 'multiply damaged sites' as critical lesions that lead to cell death. The acute health effects of radiation after doses of a few gray, are due to such cell death and consequent disturbance of cell population kinetics. Because of cellular repair and repopulation there is generally a threshold dose of about 1-2 Gy below which such severe effects are not inducible. However, more subtle, sub-lethal mutational DNA damage in somatic cells of the body and the germ cells of the ovary and testis cause the two major low dose health risks -cancer induction and genetic (heritable) effects. This paper discusses some of the epidemiological and experimental evidence regarding radiation genetic effects, carcinogenesis and CNS teratogenesis. It concludes that current risk estimates imply that about 3% of all cancers; 1% of genetic disorders and between 0% and 0.3% of severe mental subnormality in the UK is attributable to the ubiquitous background radiation. The health risks associated with the medical uses of radiation are smaller, whilst the nuclear industry causes perhaps 1% of the health detriment attributable to background doses. (author)

Use of low-dose aspirin and non-aspirin nonsteroidal anti-inflammatory drugs and risk of glioma

DEFF Research Database (Denmark)

Gaist, David; García-Rodríguez, L A; Sørensen, H T

2013-01-01

Background:Few studies have examined the association between use of aspirin or other non-steroidal anti-inflammatory drugs (NSAIDs) and risk of glioma and the results have been equivocal. We therefore investigated the influence of NSAID use on glioma risk in a nationwide setting.Methods:We used...... exposure to low-dose aspirin or non-aspirin (NA) NSAIDs into ever use or long-term use, defined as continuous use for 5 years. Conditional logistic regression was used to compute odds ratios (ORs), with 95% confidence intervals (CIs), for glioma associated with NSAID use, adjusted for potential...... confounders.Results:A total of 2688 glioma cases and 18 848 population controls were included in the study. Ever use of low-dose aspirin (OR=0.90; 95% CI: 0.77-1.04) or NA-NSAIDs (OR=1.05; 95% CI: 0.96-1.14) was not associated with glioma risk. Compared with never use, long-term use of low-dose aspirin...

Human health effects of low doses of ionizing radiation: the BEIR III controversy

International Nuclear Information System (INIS)

Radford, E.P.

1980-01-01

Controversy in the BEIR III Subcommittee on Somatic Effects concerning human health effects of low doses of low-LET radiation has centered on (a) the appropriate dose-response relationship by which extrapolation to low doses of data obtained at relatively high doses should be governed, and (b) the appropriate human evidence which should be the basis of estimation of lifetime cancer risk from radiation exposure. It is shown that the use of the linear no-threshold dose-response relationship for extrapolation purposes is an excellent approximation that is in agreement with widely accepted fundamental radiobiological principles. The appropriate human data for derivation of cancer risks are the composite age-specific risks derived from all epidemiologic studies of human cancer resulting from partial-body and whole-body radiation exposure; this composite is in good agreement with the currently available cancer incidence dose-response data obtained from the Nagasaki Tumor Registry. The current version of BEIR III significantly underestimates the radiation-induced cancer risk because it ignores the effect of high-dose-rate, low-LET radiation on cell survival in relation to cancer induction probability, and because it emphasizes cancer mortality rather than cancer incidence. The controversy and the way in which it was resolved raises important questions about how the public and its representatives can in the future obtain objective scientific evaluations of issues that may have significant economic, social, and political implications

Low doses of ionizing radiation and risk of cardiovascular disease: A review of epidemiological studies

International Nuclear Information System (INIS)

Metz-Flamant, C.; Bonaventure, A.; Tirmarche, M.; Laurier, D.; Bernier, M.O.; Milliat, F.

2009-01-01

Background While cardiovascular risks associated with high level of ionizing radiation are well-established, long-term effects of low and medium levels of exposure, between 0 and 5 gray (Gy), on the cardiovascular system are debated. Methods Available literature was reviewed considering various populations, such as survivors of atomic bombs, nuclear workers, Chernobyl liquidators, radiologists and radiological technologists and patients exposed for medical reasons. Results A significant increased risk of cardiovascular diseases associated with low doses of ionizing radiation was observed in 13 studies among the 27 analyzed. The ischemic heart diseases risk was detailed in 16 studies and seven of them showed a significant increase. The cerebrovascular risk was significantly increased in five studies among the 12 considered. Conclusion Some epidemiological and experimental data are clearly in favour of an increased cardiovascular risk associated with exposure to low doses. However, given the multi-factorial origin of cardiovascular diseases and the lack of a clear pathophysiologic mechanism, epidemiological results have to be carefully interpreted. Further research should be conducted in this area. (authors)

Estimation of radiation cancer risk in CT-KUB

Science.gov (United States)

Karim, M. K. A.; Hashim, S.; Bakar, K. A.; Bradley, D. A.; Ang, W. C.; Bahrudin, N. A.; Mhareb, M. H. A.

2017-08-01

The increased demand for computed tomography (CT) in radiological scanning examinations raises the question of a potential health impact from the associated radiation exposures. Focusing on CT kidney-ureter-bladder (CT-KUB) procedures, this work was aimed at determining organ equivalent dose using a commercial CT dose calculator and providing an estimate of cancer risks. The study, which included 64 patients (32 males and 32 females, mean age 55.5 years and age range 30-80 years), involved use of a calibrated CT scanner (Siemens-Somatom Emotion 16-slice). The CT exposures parameter including tube potential, pitch factor, tube current, volume CT dose index (CTDIvol) and dose-length product (DLP) were recorded and analyzed using CT-EXPO (Version 2.3.1, Germany). Patient organ doses, including for stomach, liver, colon, bladder, red bone marrow, prostate and ovaries were calculated and converted into cancer risks using age- and sex-specific data published in the Biological Effects of Ionizing Radiation (BEIR) VII report. With a median value scan range of 36.1 cm, the CTDIvol, DLP, and effective dose were found to be 10.7 mGy, 390.3 mGy cm and 6.2 mSv, respectively. The mean cancer risks for males and females were estimated to be respectively 25 and 46 out of 100,000 procedures with effective doses between 4.2 mSv and 10.1 mSv. Given the increased cancer risks from current CT-KUB procedures compared to conventional examinations, we propose that the low dose protocols for unenhanced CT procedures be taken into consideration before establishing imaging protocols for CT-KUB.

Low Radiation Dose and Low Cell Dose Increase the Risk of Graft Rejection in a Canine Hematopoietic Stem Cell Transplantation Model.

Science.gov (United States)

Lange, Sandra; Steder, Anne; Glass, Änne; Killian, Doreen; Wittmann, Susanne; Machka, Christoph; Werner, Juliane; Schäfer, Stephanie; Roolf, Catrin; Junghanss, Christian

2016-04-01

The canine hematopoietic stem cell transplantation (HSCT) model has become accepted in recent decades as a good preclinical model for the development of new transplantation strategies. Information on factors associated with outcome after allogeneic HSCT are a prerequisite for designing new risk-adapted transplantation protocols. Here we report a retrospective analysis aimed at identifying risk factors for allograft rejection in the canine HSCT model. A total of 75 dog leukocyte antigen-identical sibling HSCTs were performed since 2003 on 10 different protocols. Conditioning consisted of total body irradiation at 1.0 Gy (n = 20), 2.0 Gy (n = 40), or 4.5 Gy (n = 15). Bone marrow was infused either intravenously (n = 54) or intraosseously (n = 21). Cyclosporin A alone or different combinations of cyclosporine A, mycophenolate mofetil, and everolimus were used for immunosuppression. A median cell dose of 3.5 (range, 1.0 to 11.8) total nucleated cells (TNCs)/kg was infused. Cox analyses were used to assess the influence of age, weight, radiation dose, donor/recipient sex, type of immunosuppression, and cell dose (TNCs, CD34(+) cells) on allograft rejection. Initial engraftment occurred in all dogs. Forty-two dogs (56%) experienced graft rejection at median of 11 weeks (range, 6 to 56 weeks) after HSCT. Univariate analyses revealed radiation dose, type of immunosuppression, TNC dose, recipient weight, and recipient age as factors influencing long-term engraftment. In multivariate analysis, low radiation dose (P rejection. Peripheral blood mononuclear cell chimerism ≥30% (P = .008) and granulocyte chimerism ≥70% (P = .023) at 4 weeks after HSCT were independent predictors of stable engraftment. In summary, these data indicate that even in low-dose total body irradiation-based regimens, the irradiation dose is important for engraftment. The level of blood chimerism at 4 weeks post-HSCT was predictive of long-term engraftment in the canine HSCT

A methodology for estimating potential doses and risks from recycling U.S. Department of Energy radioactive scrap metals

International Nuclear Information System (INIS)

MacKinney, J.A.

1995-01-01

The U.S. Environmental Protection Agency (EPA) is considering writing regulations for the controlled use of materials originating from radioactively contaminated zones which may be recyclable. These materials include metals, such as steel (carbon and stainless), nickel, copper, aluminum and lead, from the decommissioning of federal, and non-federal facilities. To develop criteria for the release of such materials, a risk analysis of all potential exposure pathways should be conducted. These pathways include direct exposure to the recycled material by the public and workers, both individual and collective, as well as numerous other potential exposure pathways in the life of the material. EPA has developed a risk assessment methodology for estimating doses and risks associated with recycling radioactive scrap metals. This methodology was applied to metal belonging to the U.S. Department of Energy. This paper will discuss the draft EPA risk assessment methodology as a tool for estimating doses and risks from recycling. (author)

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

Low-dose total skin electron beam therapy for cutaneous lymphoma : Minimal risk of acute toxicities.

Science.gov (United States)

Kroeger, Kai; Elsayad, Khaled; Moustakis, Christos; Haverkamp, Uwe; Eich, Hans Theodor

2017-12-01

Low-dose total skin electron beam therapy (TSEBT) is attracting increased interest for the effective palliative treatment of primary cutaneous T‑cell lymphoma (pCTCL). In this study, we compared toxicity profiles following various radiation doses. We reviewed the records of 60 patients who underwent TSEBT for pCTCL between 2000 and 2016 at the University Hospital of Munster. The treatment characteristics of the radiotherapy (RT) regimens and adverse events (AEs) were then analyzed and compared. In total, 67 courses of TSEBT were administered to 60 patients. Of these patients, 34 (51%) received a standard dose with a median surface dose of 30 Gy and 33 patients (49%) received a low dose with the median surface dose of 12 Gy (7 salvage low-dose TSEBT courses were administered to 5 patients). After a median follow-up of 15 months, the overall AE rate was 100%, including 38 patients (57%) with grade 2 and 7 (10%) with grade 3 AEs. Patients treated with low-dose TSEBT had significantly fewer grade 2 AEs than those with conventional dose regimens (33 vs. 79%, P dose regimen compared to those with the conventional dose regimens (6 vs. 15%, P = 0.78). Multiple/salvage low-dose TSEBT courses were not associated with an increased risk of acute AEs. Low-dose TSEBT regimens are associated with significantly fewer grade 2 acute toxicities compared with conventional doses of TSEBT. Repeated/Salvage low-dose TSEBT, however, appears to be tolerable and can even be applied safely in patients with cutaneous relapses.

Use of doubling doses for the estimation of genetic risks

International Nuclear Information System (INIS)

Searle, A.G.

1977-01-01

Doubling dose estimates derived from radiation experiments in mice are proving of great value for the assessment of genetic hazards to man from extra radiation exposure because they allow the latest information on mutation frequencies and the incidence of genetic disease in man to be used in the assessment process. The similarity in spectra of 'spontaneous' and induced mutations increases coincidence in the validity of this approach. Data on rates of induction of dominant and recessive mutations, translocations and X-chromosome loss are used to derive doubling doses for chronic exposures to both low and high-LET radiations. Values for γ and X-rays, derived from both male and female germ-cells, fall inside a fairly small range and it is felt that the use of an overall figure of 100 rads is justifiable for protection purposes. Values for neutrons and α-particles, obtained from male germ-cells, varied according to neutron energy etc. but clustered around a value of 5 rads for fission neutrons

Techniques for detecting and determining risks from low-level radiation

International Nuclear Information System (INIS)

Boice, J.D.

1980-01-01

Epidemiology is the study of disease in man. In evaluating radiation hazards, analytic studies have utilized the cohort type of investigation (where persons exposed and not exposed to radiation are followed forward in time for determination of disease experience) or case-control approaches (where persons with and without a specific disease are evaluated for previous exposure to radiation). Most radiation studies have evaluated cohorts (e.g., radiologists), although important case-control studies have been conducted (e.g., childhood leukemia as related to prenatal x ray). At its best, epidemiology is capable fo evaluating relative risks (RR) on the order of 1.4 (i.e., a 40% relative excess). However, the RRs of interest following low doses of radiation (1 rad) are on the order of 1.02-1.002. Thus, not much should be anticipated from direct observations at 1 rad, and indirect approaches must be taken to estimate low-dose effects. Such indirect approaches include evaluating 1) populations exposed to a range of doses, both low and high, where interpolation models can be reasonably applied to estimate low-dose effects; and 2) populations exposed to fractionated doses over a long period of time where the resulting dose-effect relationship theoretically should be linear and the estimation of low-level health effects facilitated

Epistemological problems in assessing cancer risks at low radiation doses

International Nuclear Information System (INIS)

Walinder, G.

1987-01-01

Historically, biology has not been subjected to any epistemological analysis as has been the case with mathematics and physics. Our knowledge of the effects in biological systems of various stimuli proves to be dualistic in a complementary (although not mutually exclusive) way, which bears resemblance to the knowledge of phenomena in quantum physics. The dualistic limbs of biological knowledge are the action of stimuli and the response of the exposed, biological system. With regard to radiogenic cancer, this corresponds to the action of the ionizations and the response of the exposed mammal to that action, respectively. The following conclusions can be drawn from the present analysis: Predictions as to radiogenic cancer seem often if not always to have neglected the response variability (variations in radiosensitivity) in individuals or among individuals in populations, i.e. the predictions have been based exclusively on radiation doses and exposure conditions. The exposed individual or population, however, must be considered an open statistical system, i.e. a system in which predictions as to the effect of an agent are only conditionally possible. The knowledge is inverse to the size of the dose or concentration of the active agent. On epistemological grounds, we can not gain knowledge about the carcinogenic capacity of very low (non-dominant) radiation doses. Based on the same principle, we can not predict cancer risks at very low (non-dominant) radiation doses merely on the basis of models, or otherwise interpolated or extrapolated high-dose effects, observed under special exposure conditions

Effects of low doses

International Nuclear Information System (INIS)

Le Guen, B.

2001-01-01

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.)

Cancer and low dose responses in vivo: implications for radiation protection

International Nuclear Information System (INIS)

Mitchel, R.E.J.

2006-01-01

Full text: Radiation protection practices assume that cancer risk is linearly proportional to total dose, without a threshold, both for people with normal cancer risk and for people who may be genetically cancer prone. Mice heterozygous for the Tp 53 gene are cancer prone, and their increased risk from high doses was not different from Tp 53 normal mice. However, in either Tp 53 normal or heterozygous mice, a single low dose of low LET radiation given at low dose rate protected against both spontaneous and radiation-induced cancer by increasing tumor latency. Increased tumor latency without a cancer frequency change implies that low doses in vivo primarily slow the process of genomic instability, consistent with the elevated capacity for correct DSB rejoining seen in low dose exposed cells. The in vivo animal data indicates that, for low doses and low dose rates in both normal and cancer prone adult mice, risk does not increase linearly with dose, and dose thresholds for increased risk exist. Below those dose thresholds (which are influenced by Tp 53 function) overall risk is reduced below that of unexposed control mice, indicating that Dose Rate Effectiveness Factors (DREF) may approach infinity, rather than the current assumption of 2. However, as dose decreases, different tissues appear to have different thresholds at which detriment turns to protection, indicating that individual tissue weighting factors (Wt) are also not constant, but vary from positive values to zero with decreasing dose. Measurements of Relative Biological Effect between high and low LET radiations are used to establish radiation weighting factors (Wr) used in radiation protection, and these are also assumed to be constant with dose. However, since the risk from an exposure to low LET radiation is not constant with dose, it would seem unlikely that radiation-weighting factors for high LET radiation are actually constant at low dose and dose rate

Fetus dose estimate of a pregnant worker

International Nuclear Information System (INIS)

Castro, P.; Espana, M.L.; Sevillano, D.; Minguez, C.; Ferrer, C.; Lopez Franco, P.

2006-01-01

A female employee working in diagnostic radiology should take additional controls to protect the unborn child from ionizing radiations. The fetus is particularly sensitive to the effects of x-rays and, so, the determination of the equivalent dose to the unborn child is of interest for risk estimates from occupational exposures of the pregnant workers. The ian of this study is to develop a method for fetus dose estimate of a pregnant worker who participates in interventional radiology procedures. Factors for converting dosemeter readings to equivalent dose to the fetus have been measured using thermoluminescence dosimetry. Equivalent dose to the uterus is used to simulate the equivalent dose to the fetus during the first two months of pregnancy. Measurements at different depths are made to consider the variations in the position of the uterus between pregnant women. The normalized doses obtained are dependent on the beam quality. Accurate estimation of fetus doses due to occupational exposures can be made using the data provided in the current study. (Author)

Effects of low doses; Effet des faibles doses

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Le Guen, B. [Electricite de France (EDF-LAM-SCAST), 93 - Saint-Denis (France)

2001-07-01

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.)

SU-E-T-86: A Systematic Method for GammaKnife SRS Fetal Dose Estimation

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Geneser, S; Paulsson, A; Sneed, P; Braunstein, S; Ma, L [UCSF Comprehensive Cancer Center, San Francisco, CA (United States)

2015-06-15

Purpose: Estimating fetal dose is critical to the decision-making process when radiation treatment is indicated during pregnancy. Fetal doses less than 5cGy confer no measurable non-cancer developmental risks but can produce a threefold increase in developing childhood cancer. In this study, we estimate fetal dose for a patient receiving Gamma Knife stereotactic radiosurgery (GKSRS) treatment and develop a method to estimate dose directly from plan details. Methods: A patient underwent GKSRS on a Perfexion unit for eight brain metastases (two infratentorial and one brainstem). Dose measurements were performed using a CC13, head phantom, and solid water. Superficial doses to the thyroid, sternum, and pelvis were measured using MOSFETs during treatment. Because the fetal dose was too low to accurately measure, we obtained measurements proximally to the isocenter, fitted to an exponential function, and extrapolated dose to the fundus of the uterus, uterine midpoint, and pubic synthesis for both the preliminary and delivered plans. Results: The R-squared fit for the delivered doses was 0.995. The estimated fetal doses for the 72 minute preliminary and 138 minute delivered plans range from 0.0014 to 0.028cGy and 0.07 to 0.38cGy, respectively. MOSFET readings during treatment were just above background for the thyroid and negligible for all inferior positions. The method for estimating fetal dose from plan shot information was within 0.2cGy of the measured values at 14cm cranial to the fetal location. Conclusion: Estimated fetal doses for both the preliminary and delivered plan were well below the 5cGy recommended limit. Due to Pefexion shielding, internal dose is primarily governed by attenuation and drops off exponentially. This is the first work that reports fetal dose for a GK Perfexion unit. Although multiple lesions were treated and the duration of treatment was long, the estimated fetal dose remained very low.

SU-E-T-86: A Systematic Method for GammaKnife SRS Fetal Dose Estimation

International Nuclear Information System (INIS)

Geneser, S; Paulsson, A; Sneed, P; Braunstein, S; Ma, L

2015-01-01

Purpose: Estimating fetal dose is critical to the decision-making process when radiation treatment is indicated during pregnancy. Fetal doses less than 5cGy confer no measurable non-cancer developmental risks but can produce a threefold increase in developing childhood cancer. In this study, we estimate fetal dose for a patient receiving Gamma Knife stereotactic radiosurgery (GKSRS) treatment and develop a method to estimate dose directly from plan details. Methods: A patient underwent GKSRS on a Perfexion unit for eight brain metastases (two infratentorial and one brainstem). Dose measurements were performed using a CC13, head phantom, and solid water. Superficial doses to the thyroid, sternum, and pelvis were measured using MOSFETs during treatment. Because the fetal dose was too low to accurately measure, we obtained measurements proximally to the isocenter, fitted to an exponential function, and extrapolated dose to the fundus of the uterus, uterine midpoint, and pubic synthesis for both the preliminary and delivered plans. Results: The R-squared fit for the delivered doses was 0.995. The estimated fetal doses for the 72 minute preliminary and 138 minute delivered plans range from 0.0014 to 0.028cGy and 0.07 to 0.38cGy, respectively. MOSFET readings during treatment were just above background for the thyroid and negligible for all inferior positions. The method for estimating fetal dose from plan shot information was within 0.2cGy of the measured values at 14cm cranial to the fetal location. Conclusion: Estimated fetal doses for both the preliminary and delivered plan were well below the 5cGy recommended limit. Due to Pefexion shielding, internal dose is primarily governed by attenuation and drops off exponentially. This is the first work that reports fetal dose for a GK Perfexion unit. Although multiple lesions were treated and the duration of treatment was long, the estimated fetal dose remained very low

Effective dose and cancer risk in PET/CT exams

International Nuclear Information System (INIS)

Pinto, Gabriella M.; Sa, Lidia Vasconcellos de

2013-01-01

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

Monte Carlo estimation of the absorbed dose in computed tomography

Energy Technology Data Exchange (ETDEWEB)

Kim, Jin Woo; Youn, Han Bean; Kim, Ho Kyung [Pusan National University, Busan (Korea, Republic of)

2016-05-15

The purpose of this study is to devise an algorithm calculating absorbed dose distributions of patients based on Monte Carlo (MC) methods, and which includes the dose estimations due to primary and secondary (scattered) x-ray photons. Assessment of patient dose in computed tomography (CT) at the population level has become a subject of public attention and concern, and ultimate CT quality assurance and dose optimization have the goal of reducing radiation-induced cancer risks in the examined population. However, the conventional CT dose index (CTDI) concept is not a surrogate of risk but it has rather been designed to measure an average central dose. In addition, the CTDI or the dose-length product has showed troubles for helical CT with a wider beam collimation. Simple algorithms to estimate a patient specific CT dose based on the MCNP output data have been introduced. For numerical chest and head phantoms, the spatial dose distributions were calculated. The results were reasonable. The estimated dose distribution map can be readily converted into the effective dose. The important list for further studies includes the validation of the models with the experimental measurements and the acceleration of algorithms.

Cardiovascular risks associated with low dose ionizing particle radiation.

Directory of Open Access Journals (Sweden)

Xinhua Yan

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

Low risk of pulmonary tuberculosis of residents in high background radiation area, Yangjiang, China

International Nuclear Information System (INIS)

Li Xiaojuan; Sun Quanfu

2006-01-01

Objective: To examine the pulmonary tuberculosis mortality risk of the residents in high background radiation area (HBRA), Yangjiang, China. Methods: A cohort including 89 694 persons in HBRA and 35 385 persons in control area (CA) has been established since 1979. Person-year tables based on classified variables including sex, attained age, follow-up calendar year, and dose-rate group (high, intermediate, and low in HBRA, and control group) were tabulated using DATAB in EPICURE. Poisson regression analysis was used to estimate the relative risks (RR) of infectious and parasitic disease especially for pulmonary tuberculosis. Cumulative dose for each cohort member was obtained. Results: Two million person-years were accumulated by follow-up and 612 cases of pulmonary tuberculosis ascertained. Compared with risk in the control area, statistically significant lower risk of pulmonary tuberculosis was observed in HBRA among those who aged 60 years and over; markedly decreased risk occurred among males; no significant difference was found among the 6 follow-up stages, two subregions in the HBRA, or different diagnostic facilities. A statistically significantly negative dose-response was observed (P<0.001), the higher accumulative dose, the lower dose the pulmonary tuberculosis mortality risk. Its excess relative risk (ERR/Sv) was estimated to be -1.09 (95% CI: -1.34, -0.85). No established risk factors could explain this lower risk. Conclusions: The mortality of puhnonary tuberculosis among residents in HBRA who were chronically exposed to low-dose radiation was statistically significantly lower than that in the control area, and a significant dose-response relationship was observed, which probably resulted from the immunoenhancement of low dose radiation. (authors)

Exposure to low-dose radiation and the risk of breast cancer among women with a familial or genetic predisposition: a meta-analysis

International Nuclear Information System (INIS)

Jansen-van der Weide, Marijke C.; Greuter, Marcel J.W.; Pijnappel, Ruud M.; Jansen, Liesbeth; Oosterwijk, Jan C.; Bock, Geertruida H. de

2010-01-01

Women with familial or genetic aggregation of breast cancer are offered screening outside the population screening programme. However, the possible benefit of mammography screening could be reduced due to the risk of radiation-induced tumours. A systematic search was conducted addressing the question of how low-dose radiation exposure affects breast cancer risk among high-risk women. A systematic search was conducted for articles addressing breast cancer, mammography screening, radiation and high-risk women. Effects of low-dose radiation on breast cancer risk were presented in terms of pooled odds ratios (OR). Of 127 articles found, 7 were selected for the meta-analysis. Pooled OR revealed an increased risk of breast cancer among high-risk women due to low-dose radiation exposure (OR = 1.3, 95% CI: 0.9- 1.8). Exposure before age 20 (OR = 2.0, 95% CI: 1.3-3.1) or a mean of ≥5 exposures (OR = 1.8, 95% CI: 1.1-3.0) was significantly associated with a higher radiation-induced breast cancer risk. Low-dose radiation increases breast cancer risk among high-risk women. When using low-dose radiation among high-risk women, a careful approach is needed, by means of reducing repeated exposure, avoidance of exposure at a younger age and using non-ionising screening techniques. (orig.)

Relative implications of protective responses versus damage induction at low dose and low-dose-rate exposures, using the microdose approach

Energy Technology Data Exchange (ETDEWEB)

Feinendegen, L.E

2003-07-01

In reviewing tissue effects of low-dose radiation (1) absorbed dose to tissue is replaced by the sum of energy deposited with track events in cell-equivalent tissue micromasses, i.e. with microdose hits, in the number of exposed micromasses and (2) induced cell damage and adaptive protection are related to microdose hits in exposed micromasses for a given radiation quality. DNA damage increases with the number of microdose hits. They also can induce adaptive protection, mainly against endogenous DNA damage. This protection involves cellular defenses, DNA repair and damage removal. With increasing numbers of low linear energy transfer (LET) microdose hits in exposed micromasses, adaptive protection first tends to outweigh damage and then (above 200 mGy) fails and largely disappears. These experimental data predict that cancer risk coefficients derived by epidemiology at high-dose irradiation decline at low doses and dose rates when adaptive protection outdoes DNA damage. The dose-risk function should include both linear and non-linear terms at low doses. (author)

Relative implications of protective responses versus damage induction at low dose and low-dose-rate exposures, using the microdose approach

International Nuclear Information System (INIS)

Feinendegen, L.E.

2003-01-01

In reviewing tissue effects of low-dose radiation (1) absorbed dose to tissue is replaced by the sum of energy deposited with track events in cell-equivalent tissue micromasses, i.e. with microdose hits, in the number of exposed micromasses and (2) induced cell damage and adaptive protection are related to microdose hits in exposed micromasses for a given radiation quality. DNA damage increases with the number of microdose hits. They also can induce adaptive protection, mainly against endogenous DNA damage. This protection involves cellular defenses, DNA repair and damage removal. With increasing numbers of low linear energy transfer (LET) microdose hits in exposed micromasses, adaptive protection first tends to outweigh damage and then (above 200 mGy) fails and largely disappears. These experimental data predict that cancer risk coefficients derived by epidemiology at high-dose irradiation decline at low doses and dose rates when adaptive protection outdoes DNA damage. The dose-risk function should include both linear and non-linear terms at low doses. (author)

Estimating Radiological Doses to Predators Foraging in a Low-Level Radioactive Waste Management Area

International Nuclear Information System (INIS)

L.Soholt; G.Gonzales; P.Fresquez; K.Bennett; E.Lopez

2003-01-01

Since 1957, Los Alamos National Laboratory has operated Area G as its low-level, solid radioactive waste management and disposal area. Although the waste management area is developed, plants, small mammals, and avian and mammalian predators still occupy the less disturbed and revegetated portions of the land. For almost a decade, we have monitored the concentrations of selected radionuclides in soils, plants, and small mammals at Area G. The radionuclides tritium, plutonium-238, and plutonium-239 are regularly found at levels above regional background in all three media. Based on radionuclide concentrations in mice collected from 1994 to 1999, we calculated doses to higher trophic levels (owl, hawk, kestrel, and coyote) that forage on the waste management area. These predators play important functions in the regional ecosystems and are an important part of local Native American traditional tales that identify the uniqueness of their culture. The estimated doses are compared to Department of Energy's interim limit of 0.1 rad/day for the protection of terrestrial wildlife. We used exposure parameters that were derived from the literature for each receptor, including Environmental Protection Agency's exposure factors handbook. Estimated doses to predators ranged from 9E-06 to 2E-04 rad/day, assuming that they forage entirely on the waste management area. These doses are greater than those calculated for predators foraging exclusively in reference areas, but are still well below the interim dose limit. We believe that these calculated doses represent upper-bound estimates of exposure for local predators because the larger predators forage over areas that are much greater than the 63-acre waste management area. Based on these results, we concluded that predators foraging on this area do not face a hazard from radiological exposure under current site conditions

Necessary accuracy of dose estimation during cohort epidemiologic study after irradiation

International Nuclear Information System (INIS)

Orlov, M.Yu.; Stepanenko, V.F.; Khoshi, M.; Takada, Dzh.

2003-01-01

Effect of breadth of dose ranges on values of radiation risk was estimated. Ratios of observed numbers of mortalities because of leukemia in the cohort in 1950 - 1974 under deferent radiation dose to expected number of mortalities in this cohort only under background radiation were used as degree of risk. Data of cooperative Japan-American Program LSS (Life Span Study) were applied in the researches. It is established that required for the risk assessment with uncertainty 20 - 30 % the accuracy of dose estimation comprises 30 - 35 % in the range 1 - 5 rad and 5 - 10 % in the range 5 - 30 rad [ru

The Increase in Animal Mortality Risk following Exposure to Sparsely Ionizing Radiation Is Not Linear Quadratic with Dose.

Directory of Open Access Journals (Sweden)

Benjamin M Haley

Full Text Available The US government regulates allowable radiation exposures relying, in large part, on the seventh report from the committee to estimate the Biological Effect of Ionizing Radiation (BEIR VII, which estimated that most contemporary exposures- protracted or low-dose, carry 1.5 fold less risk of carcinogenesis and mortality per Gy than acute exposures of atomic bomb survivors. This correction is known as the dose and dose rate effectiveness factor for the life span study of atomic bomb survivors (DDREFLSS. It was calculated by applying a linear-quadratic dose response model to data from Japanese atomic bomb survivors and a limited number of animal studies.We argue that the linear-quadratic model does not provide appropriate support to estimate the risk of contemporary exposures. In this work, we re-estimated DDREFLSS using 15 animal studies that were not included in BEIR VII's original analysis. Acute exposure data led to a DDREFLSS estimate from 0.9 to 3.0. By contrast, data that included both acute and protracted exposures led to a DDREFLSS estimate from 4.8 to infinity. These two estimates are significantly different, violating the assumptions of the linear-quadratic model, which predicts that DDREFLSS values calculated in either way should be the same.Therefore, we propose that future estimates of the risk of protracted exposures should be based on direct comparisons of data from acute and protracted exposures, rather than from extrapolations from a linear-quadratic model. The risk of low dose exposures may be extrapolated from these protracted estimates, though we encourage ongoing debate as to whether this is the most valid approach. We also encourage efforts to enlarge the datasets used to estimate the risk of protracted exposures by including both human and animal data, carcinogenesis outcomes, a wider range of exposures, and by making more radiobiology data publicly accessible. We believe that these steps will contribute to better estimates

Low-Dose Aspirin Reduces Breast Cancer Risk in Women with Diabetes: A Nationwide Retrospective Cohort Study in Taiwan.

Science.gov (United States)

Yang, Yi-Sun; Kornelius, Edy; Chiou, Jeng-Yuan; Lai, Yung-Rung; Lo, Shih-Chang; Peng, Chiung-Huei; Huang, Chien-Ning

2017-12-01

Low-dose aspirin is commonly used for preventing cardiovascular disease in people with diabetes, but its association with cancer remains controversial. This study used a nationwide population-based reimbursement database to investigate the relationship between low-dose aspirin use and breast cancer incidence in women with diabetes. This retrospective cohort study was conducted using data retrieved from the National Health Insurance Research Database in Taiwan from January 1, 1998 to December 31, 2011. Women diagnosed as having diabetes with low-dose aspirin use (75-165 mg daily) were identified as the study population, whereas those without low-dose aspirin use were selected as the comparison group. We analyzed 148,739 patients with diabetes. Their mean age (standard deviation) was 63.3 (12.8) years. A total of 27,378 patients were taking aspirin. Overall, the use of aspirin in patients with diabetes reduced the risk of breast cancer by 18% (hazard ratio [HR], 0.82; 95% confidence interval [CI], 0.71-0.94) after adjustment for potential confounders, namely age and comorbidities. Specifically, a cumulative dose of aspirin exceeding 88,900 mg was observed to reduce the risk of breast cancer by 47% (HR, 0.53, 95% CI, 0.43-0.67); however, low (aspirin did not reduce the risk of breast cancer. Our findings suggest that a cumulative aspirin dosage of more than 88,900 mg daily was associated with a reduced risk of breast cancer in women with diabetes. However, additional studies are necessary to confirm these findings.

Estimation of outdoor and indoor effective dose and excess lifetime cancer risk from Gamma dose rates in Gonabad, Iran

Energy Technology Data Exchange (ETDEWEB)

Jafaria, R.; Zarghania, H.; Mohammadia, A., E-mail: rvzreza@gmail.com [Paramedical faculty, Birjand University of Medical Sciences, Birjand (Iran, Islamic Republic of)

2017-07-01

Background gamma irradiation in the indoor and outdoor environments is a major concern in the world. The study area was Gonabad city. Three stations and buildings for background radiation measurement of outdoor and indoor were randomly selected and the Geiger-Muller detector (X5C plus) was used. All dose rates on display of survey meter were recorded and mean of all data in each station and buildings was computed and taken as measured dose rate of that particular station. The average dose rates of background radiation were 84.2 nSv/h for outdoor and 108.6 nSv/h for indoor, maximum and minimum dose rates were 88.9 nSv/h and 77.7 nSv/h for outdoor measurements and 125.4 nSv/h and 94.1 nSv/h for indoor measurements, respectively. Results show that the annual effective dose is 0.64 mSv, which compare to global level of the annual effective dose 0.48 mSv is high. Estimated excess lifetime cancer risk was 2.24×10{sup -3} , indicated that it is large compared to the world average value of 0.25×10{sup -3}. (author)

U.S.Department of energy low dose radiation research program: potential impact on Human health risk from Chornobyl

International Nuclear Information System (INIS)

Brooks, A.

2002-01-01

Radiation risks from low levels of radiation exposure, cannot be predicted with epidemiological studies alone. Combining advances in technology with those in cell and molecular biology make it possible to detect biological changes after low doses and dose-rates of radiation exposure, such as Chornobyl. Understanding the role of these biological changes in cancer risk may or may not impact radiation protection standards. However, they will help ensure that the standards are both adequate and appropriate

Health effects of low-level ionising radiation: biological basis for risk assessment

International Nuclear Information System (INIS)

Upton, A.C.

1987-01-01

The biological basis for risk assessment is discussed. The risks of carcinogenic effects, teratogenic effects, and genetic (heritable) effects are estimated to vary in proportion with the dose of radiation in the low-dose domain; however, the risks also appear to vary with the LET of the radiation, age at the time of irradiation, and other variables. Although the data suffice to place the risks in perspective with other hazards of modern life, further research to refine the reliability of the risk assessment is called for. (author)

Radiation risk estimation

International Nuclear Information System (INIS)

Roberts, P.B.

1981-11-01

This report outlines the major publications between 1976 and 1981 that have contributed to the evolution of the way in which radiation risks (cancer and hereditary birth defects) are assessed. The publications include the latest findings of the UNSCEAR, BEIR and ICRP committees, epidemiological studies at low doses and new assessments of the doses received by the Japanese A-bomb survivors. This report is not a detailed critique of those publications, but it highlights the impact of their findings on risk assessment

Low Dose Radiation Cancer Risks: Epidemiological and Toxicological Models. Final Technical Report

International Nuclear Information System (INIS)

Hoel, David G.

2012-01-01

The basic purpose of this one year research grant was to extend the two stage clonal expansion model (TSCE) of carcinogenesis to exposures other than the usual single acute exposure. The two-stage clonal expansion model of carcinogenesis incorporates the biological process of carcinogenesis, which involves two mutations and the clonal proliferation of the intermediate cells, in a stochastic, mathematical way. The current TSCE model serves a general purpose of acute exposure models but requires numerical computation of both the survival and hazard functions. The primary objective of this research project was to develop the analytical expressions for the survival function and the hazard function of the occurrence of the first cancer cell for acute, continuous and multiple exposure cases within the framework of the piece-wise constant parameter two-stage clonal expansion model of carcinogenesis. For acute exposure and multiple exposures of acute series, it is either only allowed to have the first mutation rate vary with the dose, or to have all the parameters be dose dependent; for multiple exposures of continuous exposures, all the parameters are allowed to vary with the dose. With these analytical functions, it becomes easy to evaluate the risks of cancer and allows one to deal with the various exposure patterns in cancer risk assessment. A second objective was to apply the TSCE model with varing continuous exposures from the cancer studies of inhaled plutonium in beagle dogs. Using step functions to estimate the retention functions of the pulmonary exposure of plutonium the multiple exposure versions of the TSCE model was to be used to estimate the beagle dog lung cancer risks. The mathematical equations of the multiple exposure versions of the TSCE model were developed. A draft manuscript which is attached provides the results of this mathematical work. The application work using the beagle dog data from plutonium exposure has not been completed due to the fact

Doses and risk estimates to the human conceptus due to internal prenatal exposure to radioactive caesium

International Nuclear Information System (INIS)

Kalef-Ezra, J.A.

1997-01-01

The 1986 nuclear reactor accident at Chernobyl resulted in widespread internal contamination by radioactive caesium. The aim of the present study was to estimate the doses to embryos/fetus in Greece attributed to maternal 134 Cs and 137 Cs intake and the consequent health risks to their offspring. In pregnant women the concentration of total-body caesium (TBCs) was lower than in age-matched non-pregnant women measured during the same month. A detailed study of intake and retention in the members of one family carried out during the three years that followed the accident indicated that the biological half-time of caesium in the women decreased by a factor of two shortly after conception. Then at partus, there was an increase in the biological half-time, reaching a value similar to that before conception. The total-body potassium concentration was constant over the entire period. Doses to the embryo/fetus due to maternal intake was estimated to be about 150 μGy maximally in those conceived between November 1986 and March 1987. When conception took place later, the prenatal dose followed an exponential reduction with a half-time of about 170 d. These prenatal doses do not exceed the doses from either the natural internal potassium, or from the usual external background sources. The risks attributed to maternal 134 Cs and 137 Cs intake were considerably lower than levels that would justify consideration of termination of a pregnancy. In the absence of these data however, 2500 otherwise wanted pregnancies in Greece were terminated following the Chernobyl accident. (author)

Dose evaluation and risk estimation for secondary cancer in contralateral breast and a study of correlation between thorax shape and dose to organs at risk following tangentially breast irradiation during deep inspiration breath-hold and free breathing

International Nuclear Information System (INIS)

Johansen, Safora; Vikstroem, Johan; Blihovde Hjelstuen, Mari Helene; Mjaaland, Ingvil; Dybvik, Kjell Ivar; Olsen, Dag Rune

2011-01-01

Purpose: To assess the impact of using breathing adapted radiotherapy on contralateral breast (CB) dose, to relate the thorax shape with the dose to the organs at risk (OARs) and to predict the risk for induced malignancies in CB using linear and non-linear models, following tangential irradiation of breast. Material and methods. Sixteen patients with stage I-II breast cancer treatment planned with tangential fields using deep inspiration breath hold (DIBH) and free breathing (FB) techniques were included in this analysis. The dose results mainly based on DVH analysis were compared. Four parameters were defined to describe thoracic shape. Excess relative risk (ERR) for cancer induction in CB, employing linear and non-linear models was calculated. Results. Average CB volumes exposed to a dose of 1 Gy is 1.3 times higher in DIBH plans than in FB plans. No significant difference in average V3Gy and V5Gy for DIBH and FB plans is observed. The average mean CB dose for DIBH and FB plans is 0.33 and 0.28 Gy, respectively. No correlation between thorax shape parameters and mean OARs dose is observed. The estimated average mean ERR with linear model is lower in FB plans (0.12) than for the DIBH plans (0.14). The estimated ERR with non-linear model is 0.14 for DIBH plans and 0.15 for FB plans. Conclusion. No significant difference in CB dose between DIBH and FB plans is observed. The four thorax shape parameters defined in this study can not be related to the dose at OARs using DIBH and FB radiation techniques. The ERR estimates for secondary CB cancer are nearly the same for FB and DIBH planning when using a linear and non-linear risk prediction models

Conceptus radiation dose and risk from chest screen-film radiography

International Nuclear Information System (INIS)

Damilakis, John; Perisinakis, Kostas; Dimovasili, Evangelia; Prassopoulos, Panos; Gourtsoyiannis, Nicholas; Varveris, Haralambos

2003-01-01

The objectives of the present study were to (a) estimate the conceptus radiation dose and risks for pregnant women undergoing posteroanterior and anteroposterior (AP) chest radiographs, (b) study the conceptus dose as a function of chest thickness of the patient undergoing chest radiograph, and (c) investigate the possibility of a conceptus to receive a dose of more than 10 mGy, the level above which specific measurements of conceptus doses may be necessary. Thermoluminescent dosimeters were used for dose measurements in anthropomorphic phantoms simulating pregnancy at the three trimesters of gestation. The effect of chest thickness on conceptus dose and risk was studied by adding slabs of lucite on the anterior and posterior surface of the phantom chest. The conceptus risk for radiation-induced childhood fatal cancer and hereditary effects was calculated based on appropriate risk factors. The average AP chest dimension (d a ) was estimated for 51 women of childbearing age from chest CT examinations. The value of d a was estimated to be 22.3 cm (17.4-27.2 cm). The calculated maximum conceptus dose was 107 x 10 -3 mGy for AP chest radiographs performed during the third trimester of pregnancy with maternal chest thickness of 27.2 cm. This calculation was based on dose data obtained from measurements in the phantoms and d a estimated from the patient group. The corresponding average excess of childhood cancer was 10.7 per million patients. The risk for hereditary effects was 1.1 per million births. Radiation dose for a conceptus increases exponentially as chest thickness increases. The conceptus dose at the third trimester is higher than that of the second and first trimesters. The results of the current study suggest that chest radiographs carried out in women at any time during gestation will result in a negligible increase in risk of radiation-induced harmful effects to the unborn child. After a properly performed maternal chest X-ray, there is no need for

Conceptus radiation dose and risk from chest screen-film radiography.

Science.gov (United States)

Damilakis, John; Perisinakis, Kostas; Prassopoulos, Panos; Dimovasili, Evangelia; Varveris, Haralambos; Gourtsoyiannis, Nicholas

2003-02-01

The objectives of the present study were to (a) estimate the conceptus radiation dose and risks for pregnant women undergoing posteroanterior and anteroposterior (AP) chest radiographs, (b) study the conceptus dose as a function of chest thickness of the patient undergoing chest radiograph, and (c) investigate the possibility of a conceptus to receive a dose of more than 10 mGy, the level above which specific measurements of conceptus doses may be necessary. Thermoluminescent dosimeters were used for dose measurements in anthropomorphic phantoms simulating pregnancy at the three trimesters of gestation. The effect of chest thickness on conceptus dose and risk was studied by adding slabs of lucite on the anterior and posterior surface of the phantom chest. The conceptus risk for radiation-induced childhood fatal cancer and hereditary effects was calculated based on appropriate risk factors. The average AP chest dimension (d(a)) was estimated for 51 women of childbearing age from chest CT examinations. The value of d(a) was estimated to be 22.3 cm (17.4-27.2 cm). The calculated maximum conceptus dose was 107 x 10(-3) mGy for AP chest radiographs performed during the third trimester of pregnancy with maternal chest thickness of 27.2 cm. This calculation was based on dose data obtained from measurements in the phantoms and d(a) estimated from the patient group. The corresponding average excess of childhood cancer was 10.7 per million patients. The risk for hereditary effects was 1.1 per million births. Radiation dose for a conceptus increases exponentially as chest thickness increases. The conceptus dose at the third trimester is higher than that of the second and first trimesters. The results of the current study suggest that chest radiographs carried out in women at any time during gestation will result in a negligible increase in risk of radiation-induced harmful effects to the unborn child. After a properly performed maternal chest X-ray, there is no need for

Conceptus radiation dose and risk from chest screen-film radiography

Energy Technology Data Exchange (ETDEWEB)

Damilakis, John; Perisinakis, Kostas; Dimovasili, Evangelia [Department of Medical Physics, University of Crete, Faculty of Medicine, P.O. Box 1393, 714 09 Iraklion, Crete (Greece); Prassopoulos, Panos; Gourtsoyiannis, Nicholas [Department of Radiology, University of Crete, Faculty of Medicine, P.O. Box 1393, 714 09 Iraklion, Crete (Greece); Varveris, Haralambos [Department of Radiotherapy, University of Crete, Faculty of Medicine, P.O. Box 1393, 714 09 Iraklion, Crete (Greece)

2003-02-01

The objectives of the present study were to (a) estimate the conceptus radiation dose and risks for pregnant women undergoing posteroanterior and anteroposterior (AP) chest radiographs, (b) study the conceptus dose as a function of chest thickness of the patient undergoing chest radiograph, and (c) investigate the possibility of a conceptus to receive a dose of more than 10 mGy, the level above which specific measurements of conceptus doses may be necessary. Thermoluminescent dosimeters were used for dose measurements in anthropomorphic phantoms simulating pregnancy at the three trimesters of gestation. The effect of chest thickness on conceptus dose and risk was studied by adding slabs of lucite on the anterior and posterior surface of the phantom chest. The conceptus risk for radiation-induced childhood fatal cancer and hereditary effects was calculated based on appropriate risk factors. The average AP chest dimension (d{sub a}) was estimated for 51 women of childbearing age from chest CT examinations. The value of d{sub a} was estimated to be 22.3 cm (17.4-27.2 cm). The calculated maximum conceptus dose was 107 x 10{sup -3} mGy for AP chest radiographs performed during the third trimester of pregnancy with maternal chest thickness of 27.2 cm. This calculation was based on dose data obtained from measurements in the phantoms and d{sub a} estimated from the patient group. The corresponding average excess of childhood cancer was 10.7 per million patients. The risk for hereditary effects was 1.1 per million births. Radiation dose for a conceptus increases exponentially as chest thickness increases. The conceptus dose at the third trimester is higher than that of the second and first trimesters. The results of the current study suggest that chest radiographs carried out in women at any time during gestation will result in a negligible increase in risk of radiation-induced harmful effects to the unborn child. After a properly performed maternal chest X-ray, there is

Low dose irradiation and biological defense mechanisms

International Nuclear Information System (INIS)

Sugahara, Tsutomu; Sagan, L.A.; Aoyama, Takashi

1992-01-01

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

Post-operative high dose rate brachytherapy in patients with low to intermediate risk endometrial cancer

International Nuclear Information System (INIS)

Pearcey, R.G.; Petereit, D.G.

2000-01-01

This paper investigates the outcome using different dose/fractionation schedules in high dose rate (HDR) post-operative vaginal vault radiotherapy in patients with low to intermediate risk endometrial cancer. The world literature was reviewed and thirteen series were analyzed representing 1800 cases. A total of 12 vaginal vault recurrences were identified representing an overall vaginal control rate of 99.3%. A wide range of dose fractionation schedules and techniques have been reported. In order to analyze a dose response relationship for tumor control and complications, the biologically effective doses to the tumor and late responding tissues were calculated using the linear quadratic model. A threshold was identified for complications, but not vaginal control. While dose fractionation schedules that delivered a biologically effective dose to the late responding tissues in excess of 100 Gy 3 (LQED = 60 Gy) predicted for late complications, dose fractionation schedules that delivered a modest dose to the vaginal surface (50 Gy 10 or LQED = 30 Gy) appeared tumoricidal with vaginal control rates of at least 98%. By using convenient, modest dose fractionation schedules, HDR vaginal vault - brachytherapy yields very high local control and extremely low morbidity rates. (author)

Risk assessment and late effects of radiation in low-earth orbits

International Nuclear Information System (INIS)

Fry, R.J.M.

1989-01-01

The radiation dose rates in low-earth orbits are dependent on the altitude and orbital inclination. The doses to which the crews of space vehicles are exposed is governed by the duration of the mission and the shielding, and in low-earth orbit missions protons are the dominant particles encountered. The risk of concern with the low dose rates and the relatively low total doses of radiation that will be incurred on the space station is excess cancer. The National Council on Radiation Protection and Measurements has recently recommended career dose-equivalent limits that take into account sex and age. The new recommendations for career limits range from 1.0 Sv to 4 Sv, depending on sex and on the age at the time of their first space mission, compared to a single career limit of 4.0 Sv previously used by NASA. Risk estimates for radiated-induced cancer are evolving and changes in the current guidance may be required in the next few years. 10 refs., 1 fig., 3 tabs

Adult head CT scans: the uncertainties of effective dose estimates

International Nuclear Information System (INIS)

Gregory, Kent J.; Bibbo, Giovanni; Pattison, John E.

2008-01-01

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

Estimation of frequency, population doses and stochastic risks in brachytherapy in Japan, 1983

International Nuclear Information System (INIS)

Maruyama, Takashi; Kumamoto, Yoshikazu; Noda, Yutaka; Nishizawa, Kanae; Furuya, Yoshiro; Iwai, Kazuo.

1988-01-01

Based on the replies to a questionnaire distributed throughout Japan in 1983, genetically significant dose (GSD), per Caput mean bone marrow dose (CMD), leukemogenically significant dose (LSD), malignantly significant dose (MSD), and per Caput effective dose equivalent (EDE) from using small sealed radiation sources for radiotherapy were estimated. Annual frequencies of brachytherapy were estimated to be 2.6 x 10 3 for men and 36.3 x 10 3 for women, with a total of 38.9 x 10 3 . The annual frequencies of using afterloading technique were 0.3 x 10 3 for men and 18.8 x 10 3 for women, with a total of 19.1 x 10 3 . The annual population doses per person were 7.9 nGy for GSD, 118 μGy for CMD, 19.3 μGy for LSD, 172 μGy for MSD, and 428 μGy for EDE. The annual collective effective dose equivalent was estimated to be 5.13 x 10 4 man Sv. (Namekawa, K.)

Report on some methods of determining the state of convergence of Monte Carlo risk estimates

International Nuclear Information System (INIS)

Orford, J.L.; Hufton, D.; Johnson, K.

1991-05-01

The Department of the Environment is developing a methodology for assessing potential sites for the disposal of low and intermediate level radioactive wastes. Computer models are used to simulate the groundwater transport of radioactive materials from a disposal facility back to man. Monte Carlo methods are being employed to conduct a probabilistic risk assessment (pra) of potential sites. The models calculate time histories of annual radiation dose to the critical group population. The annual radiation dose to the critical group in turn specifies the annual individual risk. The distribution of dose is generally highly skewed and many simulation runs are required to predict the level of confidence in the risk estimate i.e. to determine whether the risk estimate is converged. This report describes some statistical methods for determining the state of convergence of the risk estimate. The methods described include the Shapiro-Wilk test, calculation of skewness and kurtosis and normal probability plots. A method for forecasting the number of samples needed before the risk estimate is converged is presented. Three case studies were conducted to examine the performance of some of these techniques. (author)

Information from the National Institute of Radiation Protection about radiation doses and radiation risks at x-ray screening

International Nuclear Information System (INIS)

1975-05-01

This report gives a specification of data concerning radiation doses and risks at x-ray investigations of lungs. The dose estimations are principally based on measurements performed in 1974 by the National Institute of Radiation Protection. The radiation doses at x-ray screening are of that magnitude that the risk for acute radiation injuries is non-existent. At these low doses it has not either been able to prove that the radiation gives long-range effects as changes in the genes or cancer of late appearance. At considerable higher doses, more than tens of thousands of millirads, a risk of cancer appearance at a small part of all irradiated persons has been proved, based on the assumption that the cancer risk is proportional to the radiation dose. Cancer can thus occure at low radiation doses too. Because of the mass radiography in Sweden 1974 about twenty cases of cancer may appear in the future. (M.S.)

Patient-specific radiation dose and cancer risk for pediatric chest CT.

Science.gov (United States)

Li, Xiang; Samei, Ehsan; Segars, W Paul; Sturgeon, Gregory M; Colsher, James G; Frush, Donald P

2011-06-01

To estimate patient-specific radiation dose and cancer risk for pediatric chest computed tomography (CT) and to evaluate factors affecting dose and risk, including patient size, patient age, and scanning parameters. The institutional review board approved this study and waived informed consent. This study was HIPAA compliant. The study included 30 patients (0-16 years old), for whom full-body computer models were recently created from clinical CT data. A validated Monte Carlo program was used to estimate organ dose from eight chest protocols, representing clinically relevant combinations of bow tie filter, collimation, pitch, and tube potential. Organ dose was used to calculate effective dose and risk index (an index of total cancer incidence risk). The dose and risk estimates before and after normalization by volume-weighted CT dose index (CTDI(vol)) or dose-length product (DLP) were correlated with patient size and age. The effect of each scanning parameter was studied. Organ dose normalized by tube current-time product or CTDI(vol) decreased exponentially with increasing average chest diameter. Effective dose normalized by tube current-time product or DLP decreased exponentially with increasing chest diameter. Chest diameter was a stronger predictor of dose than weight and total scan length. Risk index normalized by tube current-time product or DLP decreased exponentially with both chest diameter and age. When normalized by DLP, effective dose and risk index were independent of collimation, pitch, and tube potential (chest CT protocols. http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.11101900/-/DC1. RSNA, 2011

Lung cancer risk at low doses of alpha particles

International Nuclear Information System (INIS)

Hofmann, W.; Katz, R.; Zhang, C.X.

1986-01-01

A survey of inhabitant exposures arising from the inhalation of 222 Rn and 220 Rn progeny, and lung cancer mortality has been carried out in two adjacent areas in Guangdong Province, People's Republic of China, designated as the high background and the control area. Annual exposure rates are 0.38 working level months (WLM) per year in the high background, and 0.16 WLM/yr in the control area. In 14 yr of continuous study, from 1970 to 1983, age-adjusted mortality rates were found to be 2.7 per 10(5) living persons of all ages in the high background area, and 2.9 per 10(5) living persons in the control area. From this data, we conclude that we are unable to determine excess lung cancers over the normal fluctuations below a cumulative exposure of 15 WLM. This conclusion is supported by lung cancer mortality data from Austrian and Finnish high-background areas. A theoretical analysis of epidemiological data on human lung cancer incidence from inhaled 2 ]2'' 2 Rn and 220 Rn progeny, which takes into account cell killing as competitive with malignant transformation, leads to the evaluation of a risk factor which is either a linear-exponential or a quadratic-exponential function of the alpha-particle dose. Animal lung cancer data and theoretical considerations can be supplied to support either hypothesis. Thus we conclude that at our current stage of knowledge both the linear-exponential and the quadratic-exponential extrapolation to low doses seem to be equally acceptable for Rn-induced lung cancer risk, possibly suggesting a linear-quadratic transformation function with an exponential cell-killing term, or the influence of risk-modifying factors such as repair or proliferation stimuli

Topics on the problem of genetic risk estimates health research foundation

International Nuclear Information System (INIS)

Nakai, Sayaka

1995-01-01

Reanalysis of the data on untoward pregnancy outcome (UPO) for atomic bomb survivors was undertaken based on following current results of cytogenetic studies obtained in Japan: 1) Human gametes were very sensitive to the production of chromosome aberrations either spontaneous or radiation induced origin. 2) The shape of dose-response relations against to radiations showed humped curve at relatively low dose-range below 3Gy. 3) Existence of very severe selection to the embryo having chromosome aberrations represented during fetus development before the birth. It was concluded that 1) Humped dose-response model was more fitted than the linear dose model. 2) Regression coefficient for the slope of UPO at low doses derived from humped dose model was about 6 times more higher than the previous value based on linear model. 3) Risk factor for genetic detriment in term of UPO was estimated as 0.015/Gy under the condition exposed radiation below 1Gy. 4) It was difficult to find out positive evidence supporting the view which is given by Neel et al. that present estimates of doubling dose based on mouse data thought to be underestimated figure. (author)

Estimation of dose from chromosome aberration rate

International Nuclear Information System (INIS)

Li Deping

1990-01-01

The methods and skills of evaluating dose from correctly scored shromsome aberration rate are presented, and supplemented with corresponding BASIC computer code. The possibility and preventive measures of excessive probability of missing score of the aberrations in some of the current routine score methods are discussed. The use of dose-effect relationship with exposure time correction factor G in evaluating doses and their confidence intervals, dose estimation in mixed n-γ exposure, and identification of high by nonuniform acute exposure to low LET radiation and its dose estimation are discussed in more detail. The difference of estimated dose due to whether the interaction between subleisoms produced by n and γ have been taken into account is examined. In fitting the standard dose-aberration rate curve, proper weighing of experiment points and comparison with commonly accepted values are emphasised, and the coefficient of variation σ y √y of the aberration rate y as a function of dose and exposure time is given. In appendix I and II, the dose-aberration rate formula is derived from dual action theory, and the time variation of subleisom is illustrated and in appendix III, the estimation of dose from scores of two different types of aberrations (of other related score) is illustrated. Two computer codes are given in appendix IV, one is a simple code, the other a complete code, including the fitting of standard curve. the skills of using compressed data storage, and the production of simulated 'data ' for testing the curve fitting procedure are also given

Low dose irradiation and risk of leukaemia: A case-control study

International Nuclear Information System (INIS)

Chobanova, N.; Bayrakova, A.

1997-01-01

The effect of low dose irradiation (medical X-ray diagnostic) on the developing of leukaemias in adults is investigated. The influence of non-radiation agents (occupational exposure to chemical carcinogens, past viral infections, family aggregations) to leukaemias are considered also. During this retrospective study 228 patients have been examined with the following diagnosis: acute myeloid leukaemia, chronic myelogenous leukaemias, myelodisplastic syndrome and non-Hodgkin lymphoma (diagnosed between 1991-1993). Each case has been matched with two controls. Statistically significant increase has been found in the risk of developing leukaemias after X-ray diagnostic irradiation (OR = 1.98, 95% CI = 1.14 ./. 3.46). Exposure to chemical agents is also associated with significant increase in the risk (OR = 1.98, 95% CI = 1.25 ./. 2.86). (author)

Understanding and characterisation of the risks to human health from exposure to low levels of radiation

International Nuclear Information System (INIS)

Goodhead, D. T.

2009-01-01

Exposure to ionising radiation can lead to a wide variety of health effects. Cancer is judged to be the main risk from radiation at low doses and low dose rates, and controlling this risk has been the main factor in developing radiation protection practice. Conventional paradigms of radiobiology and radiation carcinogenesis have served to guide extrapolations of epidemiological data on exposed human populations, so as to estimate risks at low doses and low dose rates, to other types of ionising radiation and to non-uniform exposures. These paradigms are founded on a century of experimental and theoretical studies, but nevertheless there remain many uncertainties. Major assumptions and simplifications have been introduced to achieve a practical system of additive doses (and implied risks) for radiation protection. Advancing epidemiological studies and experimental research continue to reduce uncertainties in some areas while, in others, they raise new challenges to the generality and applicability of the conventional paradigms. (authors)

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

International Nuclear Information System (INIS)

Sheehan, Daniel M.

2006-01-01

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

Theoretical epidemiology applied to health physics: estimation of the risk of radiation-induced breast cancer

International Nuclear Information System (INIS)

Sutherland, J.V.

1983-01-01

Indirect estimation of low-dose radiation hazards is possible using the multihit model of carcinogenesis. This model is based on cancer incidence data collected over many decades on tens of millions of people. Available data on human radiation effects can be introduced into the modeling process without the requirement that these data precisely define the model to be used. This reduction in the information demanded from the limited data on human radiation effects allows a more rational approach to estimation of low-dose radiation hazards and helps to focus attention on research directed towards understanding the process of carcinogenesis, rather than on repeating human or animal experiments that cannot provide sufficient data to resolve the low-dose estimation problem. Assessment of the risk of radiation-induced breast cancer provides an excellent example of the utility of multihit modeling procedures

Assessing the reliability of dose coefficients for exposure to radioiodine by members of the public, accounting for dosimetric and risk model uncertainties.

Science.gov (United States)

Puncher, M; Zhang, W; Harrison, J D; Wakeford, R

2017-06-26

Assessments of risk to a specific population group resulting from internal exposure to a particular radionuclide can be used to assess the reliability of the appropriate International Commission on Radiological Protection (ICRP) dose coefficients used as a radiation protection device for the specified exposure pathway. An estimate of the uncertainty on the associated risk is important for informing judgments on reliability; a derived uncertainty factor, UF, is an estimate of the 95% probable geometric difference between the best risk estimate and the nominal risk and is a useful tool for making this assessment. This paper describes the application of parameter uncertainty analysis to quantify uncertainties resulting from internal exposures to radioiodine by members of the public, specifically 1, 10 and 20-year old females from the population of England and Wales. Best estimates of thyroid cancer incidence risk (lifetime attributable risk) are calculated for ingestion or inhalation of 129 I and 131 I, accounting for uncertainties in biokinetic model and cancer risk model parameter values. These estimates are compared with the equivalent ICRP derived nominal age-, sex- and population-averaged estimates of excess thyroid cancer incidence to obtain UFs. Derived UF values for ingestion or inhalation of 131 I for 1 year, 10-year and 20-year olds are around 28, 12 and 6, respectively, when compared with ICRP Publication 103 nominal values, and 9, 7 and 14, respectively, when compared with ICRP Publication 60 values. Broadly similar results were obtained for 129 I. The uncertainties on risk estimates are largely determined by uncertainties on risk model parameters rather than uncertainties on biokinetic model parameters. An examination of the sensitivity of the results to the risk models and populations used in the calculations show variations in the central estimates of risk of a factor of around 2-3. It is assumed that the direct proportionality of excess thyroid cancer

Patient dose and risk in mammography

International Nuclear Information System (INIS)

Law, J.

1991-01-01

Patient dose in mammography is estimated by two methods compared and giving agreement. A mean tissue dose of about 1 mGy per film is found for a breast of 4.5 cm compressed thickness. Variables affecting dose are then considered quantitatively, including compressed breast thickness, tube potential, grids, magnification and beam collimation. The variables having the greatest effect are breast thickness and magnification. The dose estimates are combined with existing data on breast cancer induction to predict the risk of carcinogenesis in a breast screening programme. For example, in a screening centre performing 15 000 examinations per year, only one induced cancer is predicted in about 7 years of screening under average UK conditions of age and breast thickness. (author)

Organ dose estimates for the Japanese atomic-bomb survivors

International Nuclear Information System (INIS)

Kerr, G.D.

1978-10-01

Recent studies concerning radiation risks to man by the Committee on Biological Effects of Ionizing Radiation of the National Academy of Sciences-National Research Council and the United Nations Scientific Committee on the Effects of Atomic Radiation have emphasized the need for estimates of dose to organs of the Japanese atomic-bomb survivors. Shielding of internal organs by the body has been investigated for fission-weapon gamma rays and neutrons, and ratios of mean absorbed dose in a number of organs to survivors' T65D assignments of tissue kerma in air are provided for adults. Ratios of mean absorbed dose to tissue kerma in air are provided also for the thyroid and active bone marrow of juveniles. These organ dose estimates for juveniles are of interest in studies of radiation risks due to an elevated incidence of leukemia and thyroid cancer in survivors exposed as children compared to survivors exposed as adults

Cytogenetic effects of low-dose radiation

International Nuclear Information System (INIS)

Metalli, P.

1983-01-01

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)

Low-dose radiation epidemiological studies: an assessment of methodological problems

International Nuclear Information System (INIS)

Modan, B.

1991-01-01

The present report attempts to assess the problems inherent in the analysis of low dose radiation studies, with emphasis on possible sources of methodological errors in the published data, and the consequent relevance to risk estimates. The published data examined concerned populations exposed to nuclear sources such as fallout, weapons' test or in the vicinity of nuclear reactors, occupational exposure, intra-uterine diagnostic X-rays, scattered radiation following X-ray therapy and background irradiation. (UK)

A framework for estimating radiation-related cancer risks in Japan from the 2011 Fukushima nuclear accident.

Science.gov (United States)

Walsh, L; Zhang, W; Shore, R E; Auvinen, A; Laurier, D; Wakeford, R; Jacob, P; Gent, N; Anspaugh, L R; Schüz, J; Kesminiene, A; van Deventer, E; Tritscher, A; del Rosarion Pérez, M

2014-11-01

the first year and continuing exposure, the lifetime radiation-related cancer risks based on lifetime dose (which are highest for children under 5 years of age at initial exposure), are small, and much smaller than the lifetime baseline cancer risks. For example, after initial exposure at age 1 year, the lifetime excess radiation risk and baseline risk of all solid cancers in females were estimated to be 0.7 · 10(-2) and 29.0 · 10(-2), respectively. The 15 year risks based on the lifetime reference dose are very small. However, for initial exposure in childhood, the 15 year risks based on the lifetime reference dose are up to 33 and 88% as large as the 15 year baseline risks for leukemia and thyroid cancer, respectively. The results may be scaled to particular dose estimates after consideration of caveats. One caveat is related to the lack of epidemiological evidence defining risks at low doses, because the predicted risks come from cancer risk models fitted to a wide dose range (0-4 Gy), which assume that the solid cancer and leukemia lifetime risks for doses less than about 0.5 Gy and 0.2 Gy, respectively, are proportional to organ/tissue doses: this is unlikely to seriously underestimate risks, but may overestimate risks. This WHO-HRA framework may be used to update the risk estimates, when new population health statistics data, dosimetry information and radiation risk models become available.

Biological responses to low dose rate gamma radiation

International Nuclear Information System (INIS)

Magae, Junji; Ogata, Hiromitsu

2003-01-01

Linear non-threshold (LNT) theory is a basic theory for radioprotection. While LNT dose not consider irradiation time or dose-rate, biological responses to radiation are complex processes dependent on irradiation time as well as total dose. Moreover, experimental and epidemiological studies that can evaluate LNT at low dose/low dose-rate are not sufficiently accumulated. Here we analyzed quantitative relationship among dose, dose-rate and irradiation time using chromosomal breakage and proliferation inhibition of human cells as indicators of biological responses. We also acquired quantitative data at low doses that can evaluate adaptability of LNT with statistically sufficient accuracy. Our results demonstrate that biological responses at low dose-rate are remarkably affected by exposure time, and they are dependent on dose-rate rather than total dose in long-term irradiation. We also found that change of biological responses at low dose was not linearly correlated to dose. These results suggest that it is necessary for us to create a new model which sufficiently includes dose-rate effect and correctly fits of actual experimental and epidemiological results to evaluate risk of radiation at low dose/low dose-rate. (author)

Bayesian estimation of dose rate effectiveness

International Nuclear Information System (INIS)

Arnish, J.J.; Groer, P.G.

2000-01-01

A Bayesian statistical method was used to quantify the effectiveness of high dose rate 137 Cs gamma radiation at inducing fatal mammary tumours and increasing the overall mortality rate in BALB/c female mice. The Bayesian approach considers both the temporal and dose dependence of radiation carcinogenesis and total mortality. This paper provides the first direct estimation of dose rate effectiveness using Bayesian statistics. This statistical approach provides a quantitative description of the uncertainty of the factor characterising the dose rate in terms of a probability density function. The results show that a fixed dose from 137 Cs gamma radiation delivered at a high dose rate is more effective at inducing fatal mammary tumours and increasing the overall mortality rate in BALB/c female mice than the same dose delivered at a low dose rate. (author)

Radiation dose and cancer risk among pediatric patients undergoing interventional neuroradiology procedures

International Nuclear Information System (INIS)

Thierry-Chef, Isabelle; Simon, Steven L.; Miller, Donald L.

2006-01-01

During interventional neuroradiology procedures, patients can be exposed to moderate to high levels of radiation. Special considerations are required to protect children, who are generally more sensitive to the short- and long-term detrimental effects of radiation exposure. Estimates of dose to the skin of children from certain interventional procedures have been published elsewhere, but we are not aware of data on dose to the brain or on the long-term risk of cancer from brain radiation. Our goals were to estimate radiation doses to the brain in 50 pediatric patients who had undergone cerebral embolization and to assess their lifetime risks of developing radiation-related brain cancer. Entrance-peak skin dose and various assumptions on conditions of exposure were used as input for dosimetric calculations to estimate the spatial pattern of dose within the brain and the average dose to the whole brain for each child. The average dose and the age of the child at time of exposure were used to estimate the lifetime risk of developing radiation-related brain cancer. Among the 50 patients, average radiation doses to the brain were estimated to vary from 100 mGy to 1,300 mGy if exposed to non-collimated fields and from 20 mGy to 160 mGy for collimated, moving fields. The lifetime risk of developing brain cancer was estimated to be increased by 2% to 80% as a result of the exposure. Given the very small lifetime background risk of brain tumor, the excess number of cases will be small even though the relative increase might be as high as 80%. ALARA principles of collimation and dose optimization are the most effective means to minimize the risk of future radiation-related cancer. (orig.)

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

International Nuclear Information System (INIS)

Matsudaira, Hiromichi

1977-01-01

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

The carcinogenic risks of low-LET and high-LET ionizing radiations

International Nuclear Information System (INIS)

Fabrikant, J.I.

1989-08-01

New information is available concerning the carcinogenic effects of radiation and the implications for risk assessment and risk management. This information comes from further follow-up of the epidemiological studies of the Japanese atomic bomb survivors, patients irradiated medically for cancer and allied conditions, and workers exposed in various occupations. In the Japanese atomic bomb survivors the carcinogenic risks are estimated to be somewhat higher than previously, due to the reassessment of the atomic-bomb dosimetry, further follow-up with increase in the number of excess cancer deaths, particularly in survivors irradiated early in life, and changes in the methods of analysis to compute the age-specific risks of cancer. Because of the characteristics of the atomic bomb survivor series as regards sample size, age and sex distribution, duration for follow-up, person-years at risk, and type of dosimetry, the mortality experience of the atomic bomb survivors was selected by the UNSCEAR Committee and the BEIR V Committee as the more appropriate basis for projecting risk estimates for the general population. In the atomic bomb survivors, the dose-effect relationship for overall cancer mortality other than leukemia is consistent with linearity below 3 Gy, while the dose-effect relationship for leukemia, excluding chronic lymphatic leukemia, conforms best to a linear-quadratic function. The shape of the dose-incidence curve at low doses still remains uncertain, and the data do not rule out the possible existence of a threshold for an neoplasm. The excess relative risk of mortality from all cancers combined is estimated to be 1.39 per Gy (shielded kerma), which corresponds to an absolute risk of 10.0 excess cancer deaths per 10,000 PYGy; the relative risks is 1.41 at 1 Gy (organ-absorbed dose), and an absolute risk of 13.07 excess cancer deaths per 10,000 PYGy. 19 refs

A review of radiation risk estimates

International Nuclear Information System (INIS)

1991-06-01

Three authoritative reports (UNSCEAR-1988, BEIR-V-1990, and ICRP-1990 Recommendations) on risk estimates have been reviewed and compared to previous risk estimates published by the same organizations. The ICRP now uses the term 'probability' in place of the term 'risk'. For fatal cancers, the new ICRP probability estimates are 5.0 x 10 -2 Sv -1 for a population of all ages and 4.0 x 10 -2 Sv -1 for a population of working age. For serious hereditary effects summarized over all generations, the ICRP probability coefficients are 1.0 x 10 -2 Sv -1 for a population of all ages and 0.6 x 10 -2 Sv -1 for a population of working age. For prenatal irradiation, at 8 - 15 weeks after conception, there may be a decrease of 30 I.Q. points per Sv and a risk of cancer which may lie in the range of 2 to 10 x 10 -2 Sv -1 . Based mainly on the new probability estimates the ICRP recommends a limit on effective dose of 20 mSv per year, averaged over 5 years (100 mSv in 5 years) with the further provision that the effective dose should not exceed 50 mSv in any single year. For public exposure the ICRP recommends an annual limit on effective dose of 1 mSv. However, in special circumstances, a higher value of effective dose could be allowed in a single year provided that the average over 5 five years does not exceed 1 mSv per year. Once pregnancy has been declared, the conceptus should be protected by applying a supplementary equivalent dose limit to the surface of the woman's abdomen of 2 mSv for the remainder of the pregnancy and by limiting intakes of radionuclides to about 1/20 of the annual limit on intake. A brief survey of epidemiological studies of workers and the risks from radon and thoron progeny is also included. (110 refs, 29 tabs., 10 figs.)

The Increase in Animal Mortality Risk following Exposure to Sparsely Ionizing Radiation Is Not Linear Quadratic with Dose

OpenAIRE

Haley, Benjamin M.; Paunesku, Tatjana; Grdina, David J.; Woloschak, Gayle E.

2015-01-01

Introduction The US government regulates allowable radiation exposures relying, in large part, on the seventh report from the committee to estimate the Biological Effect of Ionizing Radiation (BEIR VII), which estimated that most contemporary exposures- protracted or low-dose, carry 1.5 fold less risk of carcinogenesis and mortality per Gy than acute exposures of atomic bomb survivors. This correction is known as the dose and dose rate effectiveness factor for the life span study of atomic bo...

Genetic risks of ionizing radiation

International Nuclear Information System (INIS)

Sankaranarayanan, K.

1990-01-01

Quantitative genetic risk estimation is made using two methods: the direct method, and the doubling dose (DD) method. The doubling dose currently used is 1 Gy for low LET, low dose, low dose rate irradiation, and is based on mouse data. Tables present the 1988 UNSCEAR estimates of genetic risk using both methods. (L.L.) (Tab.)

Study of dosimetry errors in the framework of a concerted international study about the risk of cancer in nuclear industry workers. Study of the errors made on dose estimations of 100 to 3000 keV photons

International Nuclear Information System (INIS)

Thierry Chef, I.

2000-01-01

Ionizing radiations are uncontested factors of cancer risk and the radioprotection standards are defined on the basis of epidemiological studies of persons exposed to high doses of radiations (atomic bombs and therapeutic medical exposures). An epidemiological study of cancer risk has been carried out on nuclear industry workers from 17 countries in order to check these standards and to directly evaluate the risk linked with long duration exposures to low doses. The techniques used to measure the workers' doses have changed with time and these evolutions have been different in the different countries considered. The study of dosimetry errors aims at estimating the compatibility of the doses with respect to the periods of time and to the countries, and at quantifying the errors that could have disturbed the dose measurements during the first years and their consideration in the risk estimation. A compilation of the information available about dosimetry in the participating countries has been performed and the main sources of errors have been identified. Experiments have been carried out to test the response of the dosimeters used and to evaluate the conditions of exposure inside the companies. The biases and uncertainties have been estimated per company and per period of time and the most important correspond to the oldest measurements performed. This study contributes also to improve the knowledge of the working conditions and of the preciseness of dose estimations. (J.S.)

Low- and high-dose radioiodine therapy for low-/intermediate-risk differentiated thyroid cancer. A preliminary clinical trial

International Nuclear Information System (INIS)

Qu Yuan; Huang Rui; Li Lin

2017-01-01

To compare the ablation results, therapeutic responses and adverse reactions between a low dose (1.1 GBq) or high dose (3.7 GBq) of 131 I in low-/intermediate-risk differentiated thyroid cancer (DTC) patients. The factors influencing the ablation result and therapeutic response were also analyzed. The researchers used a random number table to randomly assign the enrolled patients to the low-dose group or high-dose group at a 1:1 ratio, and assessment of ablation result, therapeutic response, and adverse reactions evaluated 6 ± 3 months after therapy. A total of 140 patients were enrolled in the study through October 2014-June 2015. Until February 2016, 132 patients completed the trial. 99 patients were re-examined under thyroid-stimulating hormone (TSH) stimulation 3-9 months after 131 I therapy. For the low-dose and high-dose groups, the success rates of ablation were 52.7% (29/55) and 59.1% (26/44), respectively. The ablation results did not differ significantly between the two groups (P = 0.548). One hundred and thirty two patients were re-examined 2-9 months after 131 I therapy. The low-dose group had an excellent response rate of ∼80% (53/66), an indeterminate response rate of ∼ 20% (13/66), and no cases with a biochemical incomplete response. The high-dose group had an excellent response rate of ∼85% (36/66), an indeterminate response rate of ∼11% (7/66), and a biochemical incomplete response rate of ∼4% (3/66). No significant differences in the therapeutic response were observed between the two groups (P = 0.087). Patients in stage N1b had a significantly lower success rate of ablation than those in stage N0 (P = 0.000). The success rate of ablation increased significantly with lower thyroglobulin (Tg) levels (P = 0.000). A pre-treatment Tg level was significantly associated with a higher excellent response rate (P = 0.002). Pre-treatment-stimulated Tg of 0.47 and 3.09 μg/L were identified as cut-off values for predicting the ablation result and

Average annual doses, lifetime doses and associated risk of cancer death for radiation workers in various fuel fabrication facilities in India

International Nuclear Information System (INIS)

Iyer, P.S.; Dhond, R.V.

1980-01-01

Lifetime doses based on average annual doses are estimated for radiation workers in various fuel fabrication facilities in India. For such cumulative doses, the risk of radiation-induced cancer death is computed. The methodology for arriving at these estimates and the assumptions made are discussed. Based on personnel monitoring records from 1966 to 1978, the average annual dose equivalent for radiation workers is estimated as 0.9 mSv (90 mrem), and the maximum risk of cancer death associated with this occupational dose as 1.35x10 -5 a -1 , as compared with the risk of death due to natural causes of 7x10 -4 a -1 and the risk of death due to background radiation alone of 1.5x10 -5 a -1 . (author)

A novel tool for user-friendly estimation of natural, diagnostic and professional radiation risk: Radio-Risk software

International Nuclear Information System (INIS)

Carpeggiani, Clara; Paterni, Marco; Caramella, Davide; Vano, Eliseo; Semelka, Richard C.; Picano, Eugenio

2012-01-01

Background: Awareness of radiological risk is low among doctors and patients. An educational/decision tool that considers each patient’ s cumulative lifetime radiation exposure would facilitate provider–patient communication. Aim: The purpose of this work was to develop user-friendly software for simple estimation and communication of radiological risk to patients and doctors as a part of the SUIT-Heart (Stop Useless Imaging Testing in Heart disease) Project of the Tuscany Region. Methods: We developed a novel software program (PC-platform, Windows OS fully downloadable at (http://suit-heart.ifc.cnr.it)) considering reference dose estimates from American Heart Association Radiological Imaging 2009 guidelines and UK Royal College of Radiology 2007 guidelines. Cancer age and gender-weighted risk were derived from Biological Effects of Ionising Radiation VII Committee, 2006. Results: With simple input functions (demographics, age, gender) the user selects from a predetermined menu variables relating to natural (e.g., airplane flights and geo-tracked background exposure), professional (e.g., cath lab workers) and medical (e.g., CT, cardiac scintigraphy, coronary stenting) sources. The program provides a simple numeric (cumulative effective dose in milliSievert, mSv, and equivalent number of chest X-rays) and graphic (cumulative temporal trends of exposure, cancer cases out of 100 exposed persons) display. Conclusions: A simple software program allows straightforward estimation of cumulative dose (in multiples of chest X-rays) and risk (in extra % lifetime cancer risk), with simple numbers quantifying lifetime extra cancer risk. Pictorial display of radiation risk may be valuable for increasing radiological awareness in cardiologists.

A novel tool for user-friendly estimation of natural, diagnostic and professional radiation risk: Radio-Risk software

Energy Technology Data Exchange (ETDEWEB)

Carpeggiani, Clara; Paterni, Marco [CNR, Institute of Clinical Physiology (Italy); Caramella, Davide [Radiology Department, Pisa University, Pisa (Italy); Vano, Eliseo [San Carlos Hospital, Radiology Department, Complutense University, Madrid (Spain); Semelka, Richard C. [University of North Carolina, Chapel Hill, NC (United States); Picano, Eugenio, E-mail: picano@ifc.cnr.it [CNR, Institute of Clinical Physiology (Italy)

2012-11-15

Background: Awareness of radiological risk is low among doctors and patients. An educational/decision tool that considers each patient' s cumulative lifetime radiation exposure would facilitate provider-patient communication. Aim: The purpose of this work was to develop user-friendly software for simple estimation and communication of radiological risk to patients and doctors as a part of the SUIT-Heart (Stop Useless Imaging Testing in Heart disease) Project of the Tuscany Region. Methods: We developed a novel software program (PC-platform, Windows OS fully downloadable at (http://suit-heart.ifc.cnr.it)) considering reference dose estimates from American Heart Association Radiological Imaging 2009 guidelines and UK Royal College of Radiology 2007 guidelines. Cancer age and gender-weighted risk were derived from Biological Effects of Ionising Radiation VII Committee, 2006. Results: With simple input functions (demographics, age, gender) the user selects from a predetermined menu variables relating to natural (e.g., airplane flights and geo-tracked background exposure), professional (e.g., cath lab workers) and medical (e.g., CT, cardiac scintigraphy, coronary stenting) sources. The program provides a simple numeric (cumulative effective dose in milliSievert, mSv, and equivalent number of chest X-rays) and graphic (cumulative temporal trends of exposure, cancer cases out of 100 exposed persons) display. Conclusions: A simple software program allows straightforward estimation of cumulative dose (in multiples of chest X-rays) and risk (in extra % lifetime cancer risk), with simple numbers quantifying lifetime extra cancer risk. Pictorial display of radiation risk may be valuable for increasing radiological awareness in cardiologists.

Estimating cancer risks to adults undergoing body CT examinations

International Nuclear Information System (INIS)

Huda, W.; He, W.

2012-01-01

The purpose of the study is to estimate cancer risks from the amount of radiation used to perform body computed tomography (CT) examination. The ImPACT CT Patient Dosimetry Calculator was used to compute values of organ doses for adult body CT examinations. The radiation used to perform each examination was quantified by the dose-length product (DLP). Patient organ doses were converted into corresponding age and sex dependent cancer risks using data from BEIR VII. Results are presented for cancer risks per unit DLP and unit effective dose for 11 sensitive organs, as well as estimates of the contribution from 'other organs'. For patients who differ from a standard sized adult, correction factors based on the patient weight and antero-posterior dimension are provided to adjust organ doses and the corresponding risks. At constant incident radiation intensity, for CT examinations that include the chest, risks for females are markedly higher than those for males, whereas for examinations that include the pelvis, risks in males were slightly higher than those in females. In abdominal CT scans, risks for males and female patients are very similar. For abdominal CT scans, increasing the patient age from 20 to 80 resulted in a reduction in patient risks of nearly a factor of 5. The average cancer risk for chest/abdomen/pelvis CT examinations was ∼26 % higher than the cancer risk caused by 'sensitive organs'. Doses and radiation risks in 80 kg adults were ∼10 % lower than those in 70 kg patients. Cancer risks in body CT can be estimated from the examination DLP by accounting for sex, age, as well as patient physical characteristics. (authors)

Low Dose Suppression of Neoplastic Transformation in Vitro

Energy Technology Data Exchange (ETDEWEB)

John Leslie Redpath

2012-05-01

This grant was to study the low dose suppression of neoplastic transformation in vitro and the shape of the dose-response curve at low doses and dose-rates of ionizing radiation. Previous findings had indicated a suppression of transformation at dose <10cGy of low-LET radiation when delivered at high dose-rate. The present study indicates that such suppression extends out to doses in excess of 100cGy when the dose (from I-125 photons) is delivered at dose-rates as low as 0.2 mGy/min and out to in excess of {approx}25cGy the highest dose studied at the very low dose-rate of 0.5 mGy/day. We also examined dose-rate effects for high energy protons (which are a low-LET radiation) and suppression was evident below {approx}10cGy for high dose-rate delivery and at least out to 50cGy for low dose-rate (20cGy/h) delivery. Finally, we also examined the effect of low doses of 1 GeV/n iron ions (a high-LET radiation) delivered at high dose-rate on transformation at low doses and found a suppression below {approx}10cGy that could be attributable to an adaptive response in bystander cells induced by the associated low-LET delta rays. These results have implications for cancer risk assessment at low doses.

Absorbed Doses and Risk Estimates of {sup 211}At-MX35 F(ab'){sub 2} in Intraperitoneal Therapy of Ovarian Cancer Patients

Energy Technology Data Exchange (ETDEWEB)

Cederkrantz, Elin [Department of Radiation Physics, Institute for Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg (Sweden); Andersson, Håkan [Department of Oncology, Institute for Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg (Sweden); Bernhardt, Peter; Bäck, Tom [Department of Radiation Physics, Institute for Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg (Sweden); Hultborn, Ragnar [Department of Oncology, Institute for Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg (Sweden); Jacobsson, Lars [Department of Radiation Physics, Institute for Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg (Sweden); Jensen, Holger [PET and Cyclotron Unit, Department of Clinical Physiology and Nuclear Medicine, Copenhagen University Hospital, Copenhagen (Denmark); Lindegren, Sture [Department of Radiation Physics, Institute for Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg (Sweden); Ljungberg, Michael [Department of Medical Radiation Physics, Clinical Sciences, Lund University, Lund (Sweden); Magnander, Tobias; Palm, Stig [Department of Radiation Physics, Institute for Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg (Sweden); Albertsson, Per, E-mail: per.albertsson@oncology.gu.se [Department of Oncology, Institute for Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg (Sweden)

2015-11-01

-MX35 F(ab'){sub 2} treatment is potentially a well-tolerated therapy for locally confined microscopic ovarian cancer. Absorbed doses to normal organs are low, but because the effective dose potentially corresponds to a risk of treatment-induced carcinogenesis, optimization may still be valuable.

[Evaluation of Organ Dose Estimation from Indices of CT Dose Using Dose Index Registry].

Science.gov (United States)

Iriuchijima, Akiko; Fukushima, Yasuhiro; Ogura, Akio

Direct measurement of each patient organ dose from computed tomography (CT) is not possible. Most methods to estimate patient organ dose is using Monte Carlo simulation with dedicated software. However, dedicated software is too expensive for small scale hospitals. Not every hospital can estimate organ dose with dedicated software. The purpose of this study was to evaluate the simple method of organ dose estimation using some common indices of CT dose. The Monte Carlo simulation software Radimetrics (Bayer) was used for calculating organ dose and analysis relationship between indices of CT dose and organ dose. Multidetector CT scanners were compared with those from two manufactures (LightSpeed VCT, GE Healthcare; SOMATOM Definition Flash, Siemens Healthcare). Using stored patient data from Radimetrics, the relationships between indices of CT dose and organ dose were indicated as each formula for estimating organ dose. The accuracy of estimation method of organ dose was compared with the results of Monte Carlo simulation using the Bland-Altman plots. In the results, SSDE was the feasible index for estimation organ dose in almost organs because it reflected each patient size. The differences of organ dose between estimation and simulation were within 23%. In conclusion, our estimation method of organ dose using indices of CT dose is convenient for clinical with accuracy.

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

Science.gov (United States)

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

2018-04-01

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

Low dose effects of ionizing radiations in in vitro and in vivo biological systems: a multi-scale approach study

International Nuclear Information System (INIS)

Antoccia, A.; Berardinelli, F.; Argazzi, E.; Balata, M.; Bedogni, R.

2011-01-01

Long-term biological effects of low-dose radiation are little known nowadays and its carcinogenic risk is estimated on the assumption that risk remains linearly proportional to the radiation dose down to low-dose levels. However in the last 20 years this hypothesis has gradually begun to seem in contrast with a huge collection of experimental evidences, which has shown the presence of plethora of non-linear phenomena (including hypersensitivity and induced radioresistance, adaptive response, and non-targeted phenomena like bystander effect and genomic instability) occurring after low-dose irradiation. These phenomena might imply a non-linear behaviour of cancer risk curves in the low-dose region and question the validity of the Linear No-Threshold (LNT) model currently used for cancer risk assessment through extrapolation from existing high-dose data. Moreover only few information is available regarding the effects induced on cryo preserved cells by multi-year background radiation exposure, which might induce a radiation-damage accumulation, due to the inhibition of cellular repair mechanisms. In this framework, the multi-year Excalibur (Exposure effects at low doses of ionizing radiation in biological culture) experiment, funded by INFN-CNS5, has undertaken a multi-scale approach investigation on the biological effects induced in in vitro and in vivo biological systems, in culture and cryo preserved conditions, as a function of radiation quality (X/γ-rays, protons, He-4 ions of various energies) and dose, with particular emphasis on the low-dose region and non-linear phenomena, in terms of different biological endpoints.

The effect of low dose ionizing radiation on homeostasis and functional integrity in an organotypic human skin model

Energy Technology Data Exchange (ETDEWEB)

Neubeck, Claere von [German Cancer Consortium DKTK partner site Dresden, OncoRay - National Center for Radiation Research in Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Fetscherstrasse 74, 01307 Dresden (Germany); German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120 Heidelberg (Germany); Geniza, Matthew J. [Molecular and Cellular Biology Program, Oregon State University, Corvallis OR 97331 (United States); Kauer, Paula M.; Robinson, R. Joe; Chrisler, William B. [Health Impacts and Exposure Science, Pacific Northwest National Laboratory, Richland WA 99352 (United States); Sowa, Marianne B., E-mail: marianne.sowa@pnnl.gov [Health Impacts and Exposure Science, Pacific Northwest National Laboratory, Richland WA 99352 (United States)

2015-05-15

Highlights: • Low doses of high LET radiation influence skin homeostasis. • Effects on proliferation and differentiation profiles are LET dependent. • Skin barrier function is not compromised following low dose exposure. - Abstract: Outside the protection of Earth's atmosphere, astronauts are exposed to low doses of high linear energy transfer (LET) radiation. Future NASA plans for deep space missions or a permanent settlement on the moon are limited by the health risks associated with space radiation exposures. There is a paucity of direct epidemiological data for low dose exposures to space radiation-relevant high LET ions. Health risk models are used to estimate the risk for such exposures, though these models are based on high dose experiments. There is increasing evidence, however, that low and high dose exposures result in different signaling events at the molecular level, and may involve different response mechanisms. Further, despite their low abundance, high LET particles have been identified as the major contributor to health risk during manned space flight. The human skin is exposed in every external radiation scenario, making it an ideal epithelial tissue model in which to study radiation induced effects. Here, we exposed an in vitro three dimensional (3-D) human organotypic skin tissue model to low doses of high LET oxygen (O), silicon (Si) and iron (Fe) ions. We measured proliferation and differentiation profiles in the skin tissue and examined the integrity of the skin's barrier function. We discuss the role of secondary particles in changing the proportion of cells receiving a radiation dose, emphasizing the possible impact on radiation-induced health issues in astronauts.

Maximum likelihood estimation for cytogenetic dose-response curves

International Nuclear Information System (INIS)

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

1986-01-01

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

Low dose epidemiology

International Nuclear Information System (INIS)

Tirmarche, M.; Hubert, P.

1992-01-01

Actually, epidemiological studies have to establish if the assessment of cancer risk can be verified at low chronic radiation doses. The population surveillance must be very long, the side effects and cancers of such radiation appearing much later. In France, this epidemiological study on nuclear workers have been decided recently. Before describing the experiment and french projects in epidemiology of nuclear workers, the authors present the main english and american studies

A simple method for estimating the effective dose in dental CT. Conversion factors and calculation for a clinical low-dose protocol

International Nuclear Information System (INIS)

Homolka, P.; Kudler, H.; Nowotny, R.; Gahleitner, A.; Wien Univ.

2001-01-01

An easily appliable method to estimate effective dose including in its definition the high radio-sensitivity of the salivary glands from dental computed tomography is presented. Effective doses were calculated for a markedly dose reduced dental CT protocol as well as for standard settings. Data are compared with effective doses from the literature obtained with other modalities frequently used in dental care. Methods: Conversion factors based on the weighted Computed Tomography Dose Index were derived from published data to calculate effective dose values for various CT exposure settings. Results: Conversion factors determined can be used for clinically used kVp settings and prefiltrations. With reduced tube current an effective dose for a CT examination of the maxilla of 22 μSv can be achieved, which compares to values typically obtained with panoramic radiography (26 μSv). A CT scan of the mandible, respectively, gives 123 μSv comparable to a full mouth survey with intraoral films (150 μSv). Conclusion: For standard CT scan protocols of the mandible, effective doses exceed 600 μSv. Hence, low dose protocols for dental CT should be considered whenever feasable, especially for paediatric patients. If hard tissue diagnoses is performed, the potential of dose reduction is significant despite the higher image noise levels as readability is still adequate. (orig.) [de

Bioavailability of diclofenac potassium at low doses

Science.gov (United States)

Hinz, Burkhard; Chevts, Julia; Renner, Bertold; Wuttke, Henrike; Rau, Thomas; Schmidt, Andreas; Szelenyi, Istvan; Brune, Kay; Werner, Ulrike

2005-01-01

Aim Diclofenac-K has been recently launched at low oral doses in different countries for over-the-counter use. However, given the considerable first-pass metabolism of diclofenac, the degree of absorption of diclofenac-K at low doses remained to be determined. The aim of this study was to determine the bioavailability of low-dose diclofenac-K. Methods A randomized, three-way, cross-over study was performed in 10 subjects. Each received diclofenac-K, 22.5 mg via short-term i.v. infusion and orally at single doses of 12.5 mg and 25 mg. Results Mean (± SD) times to maximal plasma concentration (tmax) of diclofenac were 0.48 ± 0.28 h (12.5 mg) and 0.93 ± 0.96 h (25 mg). The absolute bioavailability of diclofenac-K after oral administration did not differ significantly in the 12.5-mg and 25-mg dose group (63.1 ± 12.6% vs. 65.1 ± 19.4%, respectively). The 90% confidence intervals for the AUC∞ and AUCt ratios for the two oral regimes were 82.6, 103.4% (point estimate 92.4%) and 86.2, 112.9% (point estimate 98.6%), respectively. These values were within the acceptance criteria for bioequivalence (80–125%). Conclusions Our data indicate that diclofenac-K is rapidly and well absorbed at low dose, and are consistent with a rapid onset of action of the drug. Abbreviations AUC, area under plasma concentraton-time curve; Cmax, peak plasma concentration; CI, confidence interval; COX, cyclooxygenase; D, dose; F, absolute bioavailability; tmax, time to reach Cmax. PMID:15606444

Perspectives of decision-making and estimation of risk in populations exposed to low levels of ionizing radiations

Energy Technology Data Exchange (ETDEWEB)

Fabrikant, J.I.

1979-01-01

The setting of any permissible radiation level or guide remains essentially an arbitrary procedure. Based on the radiation risk estimates derived, any lack of precision does not minimize either the need for setting public health policies nor the conclusion that such risks are extremely small when compared with those avialable of alternative options, and those normally accepted by society as the hazards of everyday life. When compared with the benefits that society has established as goals derived from the necessary activities of medical care and energy production, it is apparent that society must establish appropriate standards and seek appropriate controlling procedures which continue to assure that its needs are being met with the lowest possible risks. This implies continuing decision-making processes in which risk-benefit and cost-effectiveness assessments must be taken into account. Much of the practical information necessary for determination of radiation protection standards for public health policy is still lacking. It is now assumed that any exposure to radiaion at low levels of dose carries some risk of deleterious effects. However, how low this level may be, or the probability, or magnitude of the risk, still are not known. Radiation and the public health becomes a societal and political problem and not solely a scientific one. Our best scientific knowledge and our best scientific advice are essential for the protection of the public health, for the effective application of new technologies in medicine, and for guidance in the production of energy in industry. Unless man wishes to dispense with those activities which inevitably involve exposure to low levels of ionizing radiations, he must recognize that some degree of risk, however small, exists. In the evaluation of such risks from radiation, it is necessary to limit the radiation exposure to a level at which the risk is acceptable both to the individual and to society.

Perspectives of decision-making and estimation of risk in populations exposed to low levels of ionizing radiations

International Nuclear Information System (INIS)

Fabrikant, J.I.

1979-01-01

The setting of any permissible radiation level or guide remains essentially an arbitrary procedure. Based on the radiation risk estimates derived, any lack of precision does not minimize either the need for setting public health policies nor the conclusion that such risks are extremely small when compared with those avialable of alternative options, and those normally accepted by society as the hazards of everyday life. When compared with the benefits that society has established as goals derived from the necessary activities of medical care and energy production, it is apparent that society must establish appropriate standards and seek appropriate controlling procedures which continue to assure that its needs are being met with the lowest possible risks. This implies continuing decision-making processes in which risk-benefit and cost-effectiveness assessments must be taken into account. Much of the practical information necessary for determination of radiation protection standards for public health policy is still lacking. It is now assumed that any exposure to radiaion at low levels of dose carries some risk of deleterious effects. However, how low this level may be, or the probability, or magnitude of the risk, still are not known. Radiation and the public health becomes a societal and political problem and not solely a scientific one. Our best scientific knowledge and our best scientific advice are essential for the protection of the public health, for the effective application of new technologies in medicine, and for guidance in the production of energy in industry. Unless man wishes to dispense with those activities which inevitably involve exposure to low levels of ionizing radiations, he must recognize that some degree of risk, however small, exists. In the evaluation of such risks from radiation, it is necessary to limit the radiation exposure to a level at which the risk is acceptable both to the individual and to society

Estimation of low-level neutron dose-equivalent rate by using extrapolation method for a curie level Am–Be neutron source

International Nuclear Information System (INIS)

Li, Gang; Xu, Jiayun; Zhang, Jie

2015-01-01

Neutron radiation protection is an important research area because of the strong radiation biological effect of neutron field. The radiation dose of neutron is closely related to the neutron energy, and the connected relationship is a complex function of energy. For the low-level neutron radiation field (e.g. the Am–Be source), the commonly used commercial neutron dosimeter cannot always reflect the low-level dose rate, which is restricted by its own sensitivity limit and measuring range. In this paper, the intensity distribution of neutron field caused by a curie level Am–Be neutron source was investigated by measuring the count rates obtained through a 3 He proportional counter at different locations around the source. The results indicate that the count rates outside of the source room are negligible compared with the count rates measured in the source room. In the source room, 3 He proportional counter and neutron dosimeter were used to measure the count rates and dose rates respectively at different distances to the source. The results indicate that both the count rates and dose rates decrease exponentially with the increasing distance, and the dose rates measured by a commercial dosimeter are in good agreement with the results calculated by the Geant4 simulation within the inherent errors recommended by ICRP and IEC. Further studies presented in this paper indicate that the low-level neutron dose equivalent rates in the source room increase exponentially with the increasing low-energy neutron count rates when the source is lifted from the shield with different radiation intensities. Based on this relationship as well as the count rates measured at larger distance to the source, the dose rates can be calculated approximately by the extrapolation method. This principle can be used to estimate the low level neutron dose values in the source room which cannot be measured directly by a commercial dosimeter. - Highlights: • The scope of the affected area for

Thyroid doses and risk to paediatric patients undergoing neck CT examinations

Energy Technology Data Exchange (ETDEWEB)

Spampinato, Maria Vittoria; Tipnis, Sameer; Huda, Walter [Medical University of South Carolina, Department of Radiology and Radiological Science, Charleston, SC (United States); Tavernier, Joshua [Medical University of South Carolina, College of Medicine, Charleston, SC (United States)

2015-07-15

To estimate thyroid doses and cancer risk for paediatric patients undergoing neck computed tomography (CT). We used average CTDI{sub vol} (mGy) values from 75 paediatric neck CT examinations to estimate thyroid dose in a mathematical anthropomorphic phantom (ImPACT Patient CT Dosimetry Calculator). Patient dose was estimated by modelling the neck as mass equivalent water cylinder. A patient size correction factor was obtained using published relative dose data as a function of water cylinder size. Additional correction factors included scan length and radiation intensity variation secondary to tube-current modulation. The mean water cylinder diameter that modelled the neck was 14 ± 3.5 cm. The mathematical anthropomorphic phantom has a 16.5-cm neck, and for a constant CT exposure, would have thyroid doses that are 13-17 % lower than the average paediatric patient. CTDI{sub vol} was independent of age and sex. The average thyroid doses were 31 ± 18 mGy (males) and 34 ± 15 mGy (females). Thyroid cancer incidence risk was highest for infant females (0.2 %), lowest for teenage males (0.01 %). Estimated absorbed thyroid doses in paediatric neck CT did not significantly vary with age and gender. However, the corresponding thyroid cancer risk is determined by gender and age. (orig.)

Effective dose and cancer risk in PET/CT exams; Dose efetiva e risco de cancer em exames de PET/CT

Energy Technology Data Exchange (ETDEWEB)

Pinto, Gabriella M.; Sa, Lidia Vasconcellos de, E-mail: montezano@ird.gov.br, E-mail: Iidia@ird.gov.br [Instituto de Radioprotecao e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil)

2013-07-01

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{sup -4}. Considering that in staging of oncological diseases at least four tests are performed annually, the total risk comes to 1,03x 10{sup -3}.

Do non-targeted effects increase or decrease low dose risk in relation to the linear-non-threshold (LNT) model?

International Nuclear Information System (INIS)

Little, M.P.

2010-01-01

In this paper we review the evidence for departure from linearity for malignant and non-malignant disease and in the light of this assess likely mechanisms, and in particular the potential role for non-targeted effects. Excess cancer risks observed in the Japanese atomic bomb survivors and in many medically and occupationally exposed groups exposed at low or moderate doses are generally statistically compatible. For most cancer sites the dose-response in these groups is compatible with linearity over the range observed. The available data on biological mechanisms do not provide general support for the idea of a low dose threshold or hormesis. This large body of evidence does not suggest, indeed is not statistically compatible with, any very large threshold in dose for cancer, or with possible hormetic effects, and there is little evidence of the sorts of non-linearity in response implied by non-DNA-targeted effects. There are also excess risks of various types of non-malignant disease in the Japanese atomic bomb survivors and in other groups. In particular, elevated risks of cardiovascular disease, respiratory disease and digestive disease are observed in the A-bomb data. In contrast with cancer, there is much less consistency in the patterns of risk between the various exposed groups; for example, radiation-associated respiratory and digestive diseases have not been seen in these other (non-A-bomb) groups. Cardiovascular risks have been seen in many exposed populations, particularly in medically exposed groups, but in contrast with cancer there is much less consistency in risk between studies: risks per unit dose in epidemiological studies vary over at least two orders of magnitude, possibly a result of confounding and effect modification by well known (but unobserved) risk factors. In the absence of a convincing mechanistic explanation of epidemiological evidence that is, at present, less than persuasive, a cause-and-effect interpretation of the reported

SU-F-I-36: In-Utero Dose Measurements Within Postmortem Subjects for Estimating Fetal Doses in Pregnant Patients Examined with Pulmonary Embolism, Trauma, and Appendicitis CT

Energy Technology Data Exchange (ETDEWEB)

Lipnharski, I; Quails, N; Carranza, C; Correa, N; Bidari, S; Bickelhaup, M; Rill, L; Arreola, M [University of Florida, Gainesville, FL (United States)

2016-06-15

Purpose: The imaging of pregnant patients is medically necessary in certain clinical situations. The purpose of this work was to directly measure uterine doses in a cadaver scanned with CT protocols commonly performed on pregnant patients in order to estimate fetal dose and assess potential risk. Method: One postmortem subject was scanned on a 320-slice CT scanner with standard pulmonary embolism, trauma, and appendicitis protocols. All protocols were performed with the scan parameters and ranges currently used in clinical practice. Exams were performed both with and without iterative reconstruction to highlight the dose savings potential. Optically stimulated luminescent dosimeters (OSLDs) were inserted into the uterus in order to approximate fetal doses. Results: In the pulmonary embolism CT protocol, the uterus is outside of the primary beam, and the dose to the uterus was under 1 mGy. In the trauma and appendicitis protocols, the uterus is in the primary beam, the fetal dose estimates were 30.5 mGy for the trauma protocol, and 20.6 mGy for the appendicitis protocol. Iterative reconstruction reduced fetal doses by 30%, with uterine doses at 21.3 for the trauma and 14.3 mGy for the appendicitis protocol. Conclusion: Fetal doses were under 1 mGy when exposed to scatter radiation, and under 50 mGy when exposed to primary radiation with the trauma and appendicitis protocols. Consistent with the National Council on Radiation Protection & Measurements (NCRP) and the International Commission on Radiological Protection (ICRP), these doses exhibit a negligible risk to the fetus, with only a small increased risk of cancer. Still, CT scans are not recommended during pregnancy unless the benefits of the exam clearly outweigh the potential risk. Furthermore, when possible, pregnant patients should be examined on CT scanners equipped with iterative reconstruction in order to keep patient doses as low as reasonable achievable.

SU-F-I-36: In-Utero Dose Measurements Within Postmortem Subjects for Estimating Fetal Doses in Pregnant Patients Examined with Pulmonary Embolism, Trauma, and Appendicitis CT

International Nuclear Information System (INIS)

Lipnharski, I; Quails, N; Carranza, C; Correa, N; Bidari, S; Bickelhaup, M; Rill, L; Arreola, M

2016-01-01

Purpose: The imaging of pregnant patients is medically necessary in certain clinical situations. The purpose of this work was to directly measure uterine doses in a cadaver scanned with CT protocols commonly performed on pregnant patients in order to estimate fetal dose and assess potential risk. Method: One postmortem subject was scanned on a 320-slice CT scanner with standard pulmonary embolism, trauma, and appendicitis protocols. All protocols were performed with the scan parameters and ranges currently used in clinical practice. Exams were performed both with and without iterative reconstruction to highlight the dose savings potential. Optically stimulated luminescent dosimeters (OSLDs) were inserted into the uterus in order to approximate fetal doses. Results: In the pulmonary embolism CT protocol, the uterus is outside of the primary beam, and the dose to the uterus was under 1 mGy. In the trauma and appendicitis protocols, the uterus is in the primary beam, the fetal dose estimates were 30.5 mGy for the trauma protocol, and 20.6 mGy for the appendicitis protocol. Iterative reconstruction reduced fetal doses by 30%, with uterine doses at 21.3 for the trauma and 14.3 mGy for the appendicitis protocol. Conclusion: Fetal doses were under 1 mGy when exposed to scatter radiation, and under 50 mGy when exposed to primary radiation with the trauma and appendicitis protocols. Consistent with the National Council on Radiation Protection & Measurements (NCRP) and the International Commission on Radiological Protection (ICRP), these doses exhibit a negligible risk to the fetus, with only a small increased risk of cancer. Still, CT scans are not recommended during pregnancy unless the benefits of the exam clearly outweigh the potential risk. Furthermore, when possible, pregnant patients should be examined on CT scanners equipped with iterative reconstruction in order to keep patient doses as low as reasonable achievable.

A theoretical approach to the problem of dose-volume constraint estimation and their impact on the dose-volume histogram selection

International Nuclear Information System (INIS)

Schinkel, Colleen; Stavrev, Pavel; Stavreva, Nadia; Fallone, B. Gino

2006-01-01

This paper outlines a theoretical approach to the problem of estimating and choosing dose-volume constraints. Following this approach, a method of choosing dose-volume constraints based on biological criteria is proposed. This method is called ''reverse normal tissue complication probability (NTCP) mapping into dose-volume space'' and may be used as a general guidance to the problem of dose-volume constraint estimation. Dose-volume histograms (DVHs) are randomly simulated, and those resulting in clinically acceptable levels of complication, such as NTCP of 5±0.5%, are selected and averaged producing a mean DVH that is proven to result in the same level of NTCP. The points from the averaged DVH are proposed to serve as physical dose-volume constraints. The population-based critical volume and Lyman NTCP models with parameter sets taken from literature sources were used for the NTCP estimation. The impact of the prescribed value of the maximum dose to the organ, D max , on the averaged DVH and the dose-volume constraint points is investigated. Constraint points for 16 organs are calculated. The impact of the number of constraints to be fulfilled based on the likelihood that a DVH satisfying them will result in an acceptable NTCP is also investigated. It is theoretically proven that the radiation treatment optimization based on physical objective functions can sufficiently well restrict the dose to the organs at risk, resulting in sufficiently low NTCP values through the employment of several appropriate dose-volume constraints. At the same time, the pure physical approach to optimization is self-restrictive due to the preassignment of acceptable NTCP levels thus excluding possible better solutions to the problem

Effect of low dose tritium on mouse lymphocyte DNA estimated by comet assay

International Nuclear Information System (INIS)

Ichimasa, Yusuke; Otsuka, Kensuke; Maruyama, Satoko; Tauchi, Hiroshi; Ichimasa, Michiko; Uda, Tatsuhiko

2003-01-01

This paper deals with low dose effect of HTO on mouse lymphocytes DNA (in vitro irradiation) estimated by the comet assay using ICR male mouse of 20 to 23 weeks old. Lymphocytes were isolated by centrifugation of whole blood sample on Ficoll-Paque solution and embedded in agarose gel just after mixed with HTO. After lymphocytes were exposed to 17-50 mGy of HTO, the agarose gel slides were washed to remove HTO and cell lysis treatment on the slides was conducted before electrophoresis. The individual comets on stained slides after electrophoresis were analyzed using imaging software. No significant DNA damages were observed. (author)

Estimating the risks of cancer mortality and genetic defects resulting from exposures to low levels of ionizing radiation

International Nuclear Information System (INIS)

Buhl, T.E.; Hansen, W.R.

1984-05-01

Estimators for calculating the risk of cancer and genetic disorders induced by exposure to ionizing radiation have been recommended by the US National Academy of Sciences Committee on the Biological Effects of Ionizing Radiations, the UN Scientific Committee on the Effects of Atomic Radiation, and the International Committee on Radiological Protection. These groups have also considered the risks of somatic effects other than cancer. The US National Council on Radiation Protection and Measurements has discussed risk estimate procedures for radiation-induced health effects. The recommendations of these national and international advisory committees are summarized and compared in this report. Based on this review, two procedures for risk estimation are presented for use in radiological assessments performed by the US Department of Energy under the National Environmental Policy Act of 1969 (NEPA). In the first procedure, age- and sex-averaged risk estimators calculated with US average demographic statistics would be used with estimates of radiation dose to calculate the projected risk of cancer and genetic disorders that would result from the operation being reviewed under NEPA. If more site-specific risk estimators are needed, and the demographic information is available, a second procedure is described that would involve direct calculation of the risk estimators using recommended risk-rate factors. The computer program REPCAL has been written to perform this calculation and is described in this report. 25 references, 16 tables

Estimating the risks of cancer mortality and genetic defects resulting from exposures to low levels of ionizing radiation

Energy Technology Data Exchange (ETDEWEB)

Buhl, T.E.; Hansen, W.R.

1984-05-01

Estimators for calculating the risk of cancer and genetic disorders induced by exposure to ionizing radiation have been recommended by the US National Academy of Sciences Committee on the Biological Effects of Ionizing Radiations, the UN Scientific Committee on the Effects of Atomic Radiation, and the International Committee on Radiological Protection. These groups have also considered the risks of somatic effects other than cancer. The US National Council on Radiation Protection and Measurements has discussed risk estimate procedures for radiation-induced health effects. The recommendations of these national and international advisory committees are summarized and compared in this report. Based on this review, two procedures for risk estimation are presented for use in radiological assessments performed by the US Department of Energy under the National Environmental Policy Act of 1969 (NEPA). In the first procedure, age- and sex-averaged risk estimators calculated with US average demographic statistics would be used with estimates of radiation dose to calculate the projected risk of cancer and genetic disorders that would result from the operation being reviewed under NEPA. If more site-specific risk estimators are needed, and the demographic information is available, a second procedure is described that would involve direct calculation of the risk estimators using recommended risk-rate factors. The computer program REPCAL has been written to perform this calculation and is described in this report. 25 references, 16 tables.

Radiation dose estimates for carbon-11-labelled PET tracers

International Nuclear Information System (INIS)

Aart, Jasper van der; Hallett, William A.; Rabiner, Eugenii A.; Passchier, Jan; Comley, Robert A.

2012-01-01

Introduction: Carbon-11-labelled positron emission tomography (PET) tracers commonly used in biomedical research expose subjects to ionising radiation. Dosimetry is the measurement of radiation dose, but also commonly refers to the estimation of health risk associated with ionising radiation. This review describes radiation dosimetry of carbon-11-labelled molecules in the context of current PET research and the most widely used regulatory guidelines. Methods: A MEDLINE literature search returned 42 articles; 32 of these were based on human PET data dealing with radiation dosimetry of carbon-11 molecules. Radiation burden expressed as effective dose and maximum absorbed organ dose was compared between tracers. Results: All but one of the carbon-11-labelled PET tracers have an effective dose under 9 μSv/MBq, with a mean of 5.9 μSv/MBq. Data show that serial PET scans in a single subject are feasible for the majority of radiotracers. Conclusion: Although differing in approach, the two most widely used regulatory frameworks (those in the USA and the EU) do not differ substantially with regard to the maximum allowable injected activity per PET study. The predictive validity of animal dosimetry models is critically discussed in relation to human dosimetry. Finally, empirical PET data are related to human dose estimates based on homogenous distribution, generic models and maximum cumulated activities. Despite the contribution of these models to general risk estimation, human dosimetry studies are recommended where continued use of a new PET tracer is foreseen.

Radiation dose estimates for radiopharmaceuticals

International Nuclear Information System (INIS)

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

1996-04-01

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

Estimating population health risk from low-level environmental radon

International Nuclear Information System (INIS)

Fisher, D.R.

1980-01-01

Although incidence of respiratory cancer is directly related to inhalation of radon and radon daughters, the magnitude of the actual risk is uncertain for members of the general population exposed for long periods to low-level concentrations. Currently, any such estimate of the risk must rely on data obtained through previous studies of underground-miner populations. Several methods of risk analysis have resulted from these studies. Since the breathing atmospheres, smoking patterns, and physiology are different between miners and the general public, overestimates of lung cancer risk to the latter may have resulted. Strong evidence exists to support the theory of synergistic action between alpha radiation and other agents, and therefore a modified relative risk model was developed to predict lung cancer risks to the general public. The model considers latent period, observation period, age dependency, and inherent risks from smoking or geographical location. A test of the model showed excellent agreement with results of the study of Czechoslovakian uranium miners, for which the necessary time factors were available. The risk model was also used to predict lung cancer incidence among residents of homes on reclaimed Florida phosphate lands, and results of this analysis indicate that over the space of many years, the increased incidence of lung cancer due to elevated radon levels may be indisgtinguishable from those due to other causes

DoReMi workshop on multidisciplinary approaches to evaluating cancer risks associated with low-dose internal contamination

International Nuclear Information System (INIS)

Laurier, D.; Guseva Canu, I.; Bertho, J.M.; Blanchardon, E.; Rage, E.; Baatout, S.; Bouffler, S.; Cardis, E.; Gomolka, M.; Kreuzer, M.; Hall, J.; Kesminiene, A.

2012-01-01

A workshop dedicated to cancer risks associated with low-dose internal contamination was organised in March 2011, in Paris, in the framework of the DoReMi (Low Dose Research towards Multidisciplinary Integration) European Network of Excellence. The aim was to identify the best epidemiological studies that provide an opportunity to develop a multidisciplinary approach to improve the evaluation of the cancer risk associated with internal contamination. This workshop provided an opportunity for in-depth discussions between researchers working in different fields including (but not limited to) epidemiology, dosimetry, biology and toxicology. Discussions confirmed the importance of research on the health effects of internal contamination. Several existing epidemiological studies provide a real possibility to improve the quantification of cancer risk associated with internal emitters. Areas for future multidisciplinary collaborations were identified, that should allow feasibility studies to be carried out in the near future. The goal of this paper is to present an overview of the presentations and discussions that took place during this workshop. (authors)

Dose-stochastic radiobiological effect relationship in model of two reactions and estimation of radiation risk

International Nuclear Information System (INIS)

Komochkov, M.M.

1997-01-01

The model of dose-stochastic effect relationship for biological systems capable of self-defence under danger factor effect is developed. A defence system is realized in two forms of organism reaction, which determine innate μ n and adaptive μ a radiosensitivities. The significances of μ n are determined by host (inner) factors; and the significances of μ a , by external factors. The possibilities of adaptive reaction are determined by the coefficient of capabilities of the defence system. The formulas of the dose-effect relationship are the solutions of differential equations of assumed process in the defence system of organism. The model and formulas have been checked both at cell and at human levels. Based on the model and personal monitoring data, the estimation of radiation risk at the Joint Institute for Nuclear Research is done

Low dose irradiation facilitates hepatocellular carcinoma genesis involving HULC.

Science.gov (United States)

Li, Yuan; Ge, Chang; Feng, Guoxing; Xiao, Huiwen; Dong, Jiali; Zhu, Changchun; Jiang, Mian; Cui, Ming; Fan, Saijun

2018-03-24

Irradiation exposure positive correlates with tumor formation, such as breast cancer and lung cancer. However, whether low dose irradiation induces hepatocarcinogenesis and the underlying mechanism remain poorly defined. In the present study, we reported that low dose irradiation facilitated the proliferation of hepatocyte through up-regulating HULC in vitro and in vivo. Low dose irradiation exposure elevated HULC expression level in hepatocyte. Deletion of heightened HULC erased the cells growth accelerated following low dose irradiation exposure. CDKN1, the neighbor gene of HULC, was down-regulated by overexpression of HULC following low dose irradiation exposure via complementary base pairing, resulting in promoting cell cycle process. Thus, our findings provide new insights into the mechanism of low dose irradiation-induced hepatocarcinogenesis through HULC/CDKN1 signaling, and shed light on the potential risk of low dose irradiation for the development of hepatocellular carcinoma in pre-clinical settings. © 2018 Wiley Periodicals, Inc.

Low-dose total skin electron beam therapy for cutaneous lymphoma. Minimal risk of acute toxicities

Energy Technology Data Exchange (ETDEWEB)

Kroeger, Kai; Elsayad, Khaled; Moustakis, Christos; Haverkamp, Uwe; Eich, Hans Theodor [University Hospital of Muenster, Department of Radiation Oncology, Muenster (Germany)

2017-12-15

Low-dose total skin electron beam therapy (TSEBT) is attracting increased interest for the effective palliative treatment of primary cutaneous T-cell lymphoma (pCTCL). In this study, we compared toxicity profiles following various radiation doses. We reviewed the records of 60 patients who underwent TSEBT for pCTCL between 2000 and 2016 at the University Hospital of Munster. The treatment characteristics of the radiotherapy (RT) regimens and adverse events (AEs) were then analyzed and compared. In total, 67 courses of TSEBT were administered to 60 patients. Of these patients, 34 (51%) received a standard dose with a median surface dose of 30 Gy and 33 patients (49%) received a low dose with the median surface dose of 12 Gy (7 salvage low-dose TSEBT courses were administered to 5 patients). After a median follow-up of 15 months, the overall AE rate was 100%, including 38 patients (57%) with grade 2 and 7 (10%) with grade 3 AEs. Patients treated with low-dose TSEBT had significantly fewer grade 2 AEs than those with conventional dose regimens (33 vs. 79%, P < 0.001). A lower grade 3 AE rate was also observed in patients who had received the low-dose regimen compared to those with the conventional dose regimens (6 vs. 15%, P = 0.78). Multiple/salvage low-dose TSEBT courses were not associated with an increased risk of acute AEs. Low-dose TSEBT regimens are associated with significantly fewer grade 2 acute toxicities compared with conventional doses of TSEBT. Repeated/Salvage low-dose TSEBT, however, appears to be tolerable and can even be applied safely in patients with cutaneous relapses. (orig.) [German] Eine niedrigdosierte Ganzhautelektronenbestrahlung (TSEBT) wird vermehrt zur effektiven palliativen Behandlung von Patienten mit primaer kutanen T-Zell-Lymphomen (pCTCL) eingesetzt. In dieser Studie vergleichen wir die Toxizitaetsprofile verschiedener Dosiskonzepte. Untersucht wurden 60 zwischen 2000 und 2016 am Universitaetsklinikum Muenster mittels TSEBT

Stochastic risk estimation from medical x-ray diagnostic examinations, 3

International Nuclear Information System (INIS)

Hashizume, Tadashi; Maruyama, Takashi; Noda, Yutaka; Iwai, Kazuo; Fukuhisa, Kenjiro

1981-01-01

The genetically significant dose (GSD), per Caput mean bone marrow dose (CMD), leukemia significant dose (LSD) and malignancy significant dose (MSD) from medical diagnostic X-ray examinations in Japan were estimated based on a 1979 nationwide survey of randomly sampled hospitals and clinics. The population risk estimates were carried out using the resultant values of GSD, LSD and MSD. In the risk estimates, the significant factors, namely, the relative child expectancy, the leukemia significant factor and the malignancy significant factor, for patients were assumed to be same as those of general population. The risk factors used were 185 x 10 -6 rad -1 for genetic risk of all generations, 20 x 10 -6 rad -1 for fatal leukemia and 165 x 10 -6 rad -1 for fatal malignant diseases, respectively. The resultant annual population doses per person were 15 mrad (0.15 mGy) for GSD, 107 mrad (1.07 mGy) for CMD, 86 mrad (0.86 mGy) for LSD and 43 mrad (0.43 mGy) for MSD, respectively. The present data other than the MSD were compared with the data in 1960, 1969 and 1974. For example, the GSD of 1979 was approximately same as that of 1974, although the annual number of examinations in 1979 increased by about 30 percent as compared with those of 1974. The population risks from X-ray diagnosis were estimated to be 260 persons per year for genetic risk of all generations, 192 person per year for fatal leukemic risk and 825 person per year for malignant risk, respectively, for the whole population in Japan, assuming that the X-ray diagnosis in 1979 will be performed continuously in the future. The average risks per one exposure for X-ray radiography were estimated using the weighted average of the significant factor and the organ or tissue dose with the number of radiographic exposures by age and by type of examination. The average risks per radiographic exposure were 176 x 10 -9 for genetic risk, 285 x 10 -9 for leukemic risk and 1.75 x 10 -6 for malignant risk respectively. (author)

Systematic review on physician's knowledge about radiation doses and radiation risks of computed tomography

International Nuclear Information System (INIS)

Krille, Lucian; Hammer, Gael P.; Merzenich, Hiltrud; Zeeb, Hajo

2010-01-01

Background: The frequent use of computed tomography is a major cause of the increasing medical radiation exposure of the general population. Consequently, dose reduction and radiation protection is a topic of scientific and public concern. Aim: We evaluated the available literature on physicians' knowledge regarding radiation dosages and risks due to computed tomography. Methods: A systematic review in accordance with the Cochrane and PRISMA statements was performed using eight databases. 3091 references were found. Only primary studies assessing physicians' knowledge about computed tomography were included. Results: 14 relevant articles were identified, all focussing on dose estimations for CT. Overall, the surveys showed moderate to low knowledge among physicians concerning radiation doses and the involved health risks. However, the surveys varied considerably in conduct and quality. For some countries, more than one survey was available. There was no general trend in knowledge in any country except a slight improvement of knowledge on health risks and radiation doses in two consecutive local German surveys. Conclusions: Knowledge gaps concerning radiation doses and associated health risks among physicians are evident from published research. However, knowledge on radiation doses cannot be interpreted as reliable indicator for good medical practice.

Breast cancer incidence following low-dose rate environmental exposure: Techa River Cohort, 1956–2004

Science.gov (United States)

Ostroumova, E; Preston, D L; Ron, E; Krestinina, L; Davis, F G; Kossenko, M; Akleyev, A

2008-01-01

In the 1950s, the Mayak nuclear weapons facility in Russia discharged liquid radioactive wastes into the Techa River causing exposure of riverside residents to protracted low-to-moderate doses of radiation. Almost 10 000 women received estimated doses to the stomach of up to 0.47 Gray (Gy) (mean dose=0.04 Gy) from external γ-exposure and 137Cs incorporation. We have been following this population for cancer incidence and mortality and as in the general Russian population, we found a significant temporal trend of breast cancer incidence. A significant linear radiation dose–response relationship was observed (P=0.01) with an estimated excess relative risk per Gray (ERR/Gy) of 5.00 (95% confidence interval (CI), 0.80, 12.76). We estimated that approximately 12% of the 109 observed cases could be attributed to radiation. PMID:19002173

Methods for Estimation of Radiation Risk in Epidemiological Studies Accounting for Classical and Berkson Errors in Doses

KAUST Repository

Kukush, Alexander

2011-01-16

With a binary response Y, the dose-response model under consideration is logistic in flavor with pr(Y=1 | D) = R (1+R)(-1), R = λ(0) + EAR D, where λ(0) is the baseline incidence rate and EAR is the excess absolute risk per gray. The calculated thyroid dose of a person i is expressed as Dimes=fiQi(mes)/Mi(mes). Here, Qi(mes) is the measured content of radioiodine in the thyroid gland of person i at time t(mes), Mi(mes) is the estimate of the thyroid mass, and f(i) is the normalizing multiplier. The Q(i) and M(i) are measured with multiplicative errors Vi(Q) and ViM, so that Qi(mes)=Qi(tr)Vi(Q) (this is classical measurement error model) and Mi(tr)=Mi(mes)Vi(M) (this is Berkson measurement error model). Here, Qi(tr) is the true content of radioactivity in the thyroid gland, and Mi(tr) is the true value of the thyroid mass. The error in f(i) is much smaller than the errors in ( Qi(mes), Mi(mes)) and ignored in the analysis. By means of Parametric Full Maximum Likelihood and Regression Calibration (under the assumption that the data set of true doses has lognormal distribution), Nonparametric Full Maximum Likelihood, Nonparametric Regression Calibration, and by properly tuned SIMEX method we study the influence of measurement errors in thyroid dose on the estimates of λ(0) and EAR. The simulation study is presented based on a real sample from the epidemiological studies. The doses were reconstructed in the framework of the Ukrainian-American project on the investigation of Post-Chernobyl thyroid cancers in Ukraine, and the underlying subpolulation was artificially enlarged in order to increase the statistical power. The true risk parameters were given by the values to earlier epidemiological studies, and then the binary response was simulated according to the dose-response model.

Methods for estimation of radiation risk in epidemiological studies accounting for classical and Berkson errors in doses.

Science.gov (United States)

Kukush, Alexander; Shklyar, Sergiy; Masiuk, Sergii; Likhtarov, Illya; Kovgan, Lina; Carroll, Raymond J; Bouville, Andre

2011-02-16

With a binary response Y, the dose-response model under consideration is logistic in flavor with pr(Y=1 | D) = R (1+R)(-1), R = λ(0) + EAR D, where λ(0) is the baseline incidence rate and EAR is the excess absolute risk per gray. The calculated thyroid dose of a person i is expressed as Dimes=fiQi(mes)/Mi(mes). Here, Qi(mes) is the measured content of radioiodine in the thyroid gland of person i at time t(mes), Mi(mes) is the estimate of the thyroid mass, and f(i) is the normalizing multiplier. The Q(i) and M(i) are measured with multiplicative errors Vi(Q) and ViM, so that Qi(mes)=Qi(tr)Vi(Q) (this is classical measurement error model) and Mi(tr)=Mi(mes)Vi(M) (this is Berkson measurement error model). Here, Qi(tr) is the true content of radioactivity in the thyroid gland, and Mi(tr) is the true value of the thyroid mass. The error in f(i) is much smaller than the errors in ( Qi(mes), Mi(mes)) and ignored in the analysis. By means of Parametric Full Maximum Likelihood and Regression Calibration (under the assumption that the data set of true doses has lognormal distribution), Nonparametric Full Maximum Likelihood, Nonparametric Regression Calibration, and by properly tuned SIMEX method we study the influence of measurement errors in thyroid dose on the estimates of λ(0) and EAR. The simulation study is presented based on a real sample from the epidemiological studies. The doses were reconstructed in the framework of the Ukrainian-American project on the investigation of Post-Chernobyl thyroid cancers in Ukraine, and the underlying subpolulation was artificially enlarged in order to increase the statistical power. The true risk parameters were given by the values to earlier epidemiological studies, and then the binary response was simulated according to the dose-response model.

Low dose ionizing radiation exposure and cardiovascular disease mortality: cohort study based on Canadian national dose registry of radiation workers

International Nuclear Information System (INIS)

Zielinski, J. M.; Band, P. R.; Ashmore, P. J.; Jiang, H.; Shilnikova, N. S.; Tait, V. K.; Krewski, D.

2009-01-01

The purpose of our study was to assess the risk of cardiovascular disease (CVD) mortality in a Canadian cohort of 337 397 individuals (169 256 men and 168 141 women) occupationally exposed to ionizing radiation and included in the National Dose Registry (NDR) of Canada. Material and Methods: Exposure to high doses of ionizing radiation, such as those received during radiotherapy, leads to increased risk of cardiovascular diseases. The emerging evidence of excess risk of CVDs after exposure to doses well below those previously considered as safe warrants epidemiological studies of populations exposed to low levels of ionizing radiation. In the present study, the cohort consisted of employees at nuclear power stations (nuclear workers) as well as medical, dental and industrial workers. The mean whole body radiation dose was 8.6 mSv for men and 1.2 mSv for women. Results: During the study period (1951 - 1995), as many as 3 533 deaths from cardiovascular diseases have been identified (3 018 among men and 515 among women). In the cohort, CVD mortality was significantly lower than in the general population of Canada. The cohort showed a significant dose response both among men and women. Risk estimates of CVD mortality in the NDR cohort, when expressed as excess relative risk per unit dose, were higher than those in most other occupational cohorts and higher than in the studies of Japanese atomic bomb survivors. Conclusions: The study has demonstrated a strong positive association between radiation dose and the risk of CVD mortality. Caution needs to be exercised when interpreting these results, due to the potential bias introduced by dosimetry uncertainties, the possible record linkage errors, and especially by the lack of adjustment for non-radiation risk factors. (authors)

Radon Exposure and the Definition of Low Doses-The Problem of Spatial Dose Distribution.

Science.gov (United States)

Madas, Balázs G

2016-07-01

Investigating the health effects of low doses of ionizing radiation is considered to be one of the most important fields in radiological protection research. Although the definition of low dose given by a dose range seems to be clear, it leaves some open questions. For example, the time frame and the target volume in which absorbed dose is measured have to be defined. While dose rate is considered in the current system of radiological protection, the same cancer risk is associated with all exposures, resulting in a given amount of energy absorbed by a single target cell or distributed among all the target cells of a given organ. However, the biological effects and so the health consequences of these extreme exposure scenarios are unlikely to be the same. Due to the heterogeneous deposition of radon progeny within the lungs, heterogeneous radiation exposure becomes a practical issue in radiological protection. While the macroscopic dose is still within the low dose range, local tissue doses on the order of Grays can be reached in the most exposed parts of the bronchial airways. It can be concluded that progress in low dose research needs not only low dose but also high dose experiments where small parts of a biological sample receive doses on the order of Grays, while the average dose over the whole sample remains low. A narrow interpretation of low dose research might exclude investigations with high relevance to radiological protection. Therefore, studies important to radiological protection should be performed in the frame of low dose research even if the applied doses do not fit in the dose range used for the definition of low doses.

Phantom measurements and computed estimates of breast dose with radiotherapy for Hodgkin's lymphoma: dose reduction with the use of the involved field

International Nuclear Information System (INIS)

Wirth, A.; Kron, T.; Sorell, G.; Cramb, J.; Wittwer, H.; Sullivan, K.

2008-01-01

Full text: The risk of breast cancer following radiotherapy for Hodgkin's lymphoma appears to be dose related. In this study we compared breast dose in an anthropomorphic phantom for conventional 'mantle'; upper mediastinal/bilateral neck (minimantle) and unilateral neck fields, and evaluated the accuracy of computer planned dose estimates for out-of-field doses. For each field, computer-planned breast dose (CPD) estimates were compared with thermolu-minescence dosimetry measurements in five locations within 'breast tissue'. CPD were also compared with ion chamber measurements in a slab phantom. Measured dose and CPD were within 20% of each other up to approximately 10 cm from the field edge. Beyond 10 cm, the CPD underestimated dose by a factor of 2 or more. The minimantle reduced the breast dose by a factor of approximately 10 compared with the mantle treatment. Treating the neck field lowered the breast dose by a further 50% or more. Modern involved-field radiotherapy for lymphoma substantially reduces breast dose compared with mantle fields. Computer dosimetery underestimated dose at larger distances from the field. This needs to be considered if computer dosimetery is used to estimate breast dose and, by extrapolation, breast cancer risk.

Incidence of intracranial bleeds in new users of low-dose aspirin: a cohort study using The Health Improvement Network.

Science.gov (United States)

Cea Soriano, L; Gaist, D; Soriano-Gabarró, M; García Rodríguez, L A

2017-06-01

Essentials Intracranial bleeds (ICB) are serious clinical events that have been associated with aspirin use. Incidence rates of ICB were calculated among new-users of low-dose aspirin in the UK (2000-2012). Over a median follow-up of 5.58 years, the incidence of ICB was 0.08 per 100 person-years. Our estimates are valuable for inclusion in risk-benefit assessments of low-dose aspirin use. Background Low-dose aspirin protects against both ischemic cardiovascular (CV) events and colorectal cancer (CRC). However, low-dose aspirin may be associated with a slightly increased risk of intracranial bleeds (ICBs). Objectives To obtain the incidence rates of ICBs overall and by patient subgroups among new users of low-dose aspirin. Patients/Methods Using The Health Improvement Network (THIN) UK primary-care database (2000-2012), we identified a cohort of new users of low-dose aspirin aged 40-84 years (N = 199 079; mean age at start of follow-up, 63.9 years) and followed them for up to 14 years (median 5.58 years). Incident ICB cases were identified and validated through linkage to hospitalization data and/or review of THIN records with free-text comments. Incidence rates with 95% confidence intervals (CIs) were calculated. Results Eight hundred and eighty-one incident ICBs cases were identified: 407 cases of intracerebral hemorrhage (ICH), 283 cases of subdural hematoma (SDH), and 191 cases of subarachnoid hemorrhage (SAH). Incidence rates per 100 person-years were 0.08 (95% CI 0.07-0.08) for all ICBs, 0.04 (95% CI 0.03-0.04) for ICH, 0.03 (95% CI 0.02-0.03) for SDH, and 0.02 (95% CI 0.01-0.02) for SAH. The ICB incidence rates per 100 person-years for individuals with an indication of primary CV disease prevention were 0.07 (95% CI 0.06-0.07) and 0.09 (95% CI 0.08-0.10) for secondary CV disease prevention. Incidence rates were higher in men for SDH, and higher in women for ICH and SAH. Conclusions Our results provide valuable estimates of the absolute ICB risk for

Current features on risk perception and risk communication of radiation

International Nuclear Information System (INIS)

Kusama, Tomoko

1997-01-01

Health effects and risks of radiation and radionuclides are being misunderstood by many members of general public. Many peoples have fear and anxieties for radiation. So far, the health effects from radiation at low dose and low dose rate have not been cleared on biological aspects. Then, we have quantitatively estimated health risks of low-dose radiation on the basis of linear dose response relationship without threshold from the viewpoints of radiation protection by using both epidemiological data, such as atomic bomb survivors, and some models and assumptions. It is important for researchers and relevant persons in radiation protection to understand the process of risk estimation of radiation and to communicate an exact knowledge of radiation risks of the public members. (author)

Poisson–Gaussian Noise Analysis and Estimation for Low-Dose X-ray Images in the NSCT Domain

Science.gov (United States)

Lee, Sangyoon; Lee, Min Seok; Kang, Moon Gi

2018-01-01

The noise distribution of images obtained by X-ray sensors in low-dosage situations can be analyzed using the Poisson and Gaussian mixture model. Multiscale conversion is one of the most popular noise reduction methods used in recent years. Estimation of the noise distribution of each subband in the multiscale domain is the most important factor in performing noise reduction, with non-subsampled contourlet transform (NSCT) representing an effective method for scale and direction decomposition. In this study, we use artificially generated noise to analyze and estimate the Poisson–Gaussian noise of low-dose X-ray images in the NSCT domain. The noise distribution of the subband coefficients is analyzed using the noiseless low-band coefficients and the variance of the noisy subband coefficients. The noise-after-transform also follows a Poisson–Gaussian distribution, and the relationship between the noise parameters of the subband and the full-band image is identified. We then analyze noise of actual images to validate the theoretical analysis. Comparison of the proposed noise estimation method with an existing noise reduction method confirms that the proposed method outperforms traditional methods. PMID:29596335

Poisson-Gaussian Noise Analysis and Estimation for Low-Dose X-ray Images in the NSCT Domain.

Science.gov (United States)

Lee, Sangyoon; Lee, Min Seok; Kang, Moon Gi

2018-03-29

The noise distribution of images obtained by X-ray sensors in low-dosage situations can be analyzed using the Poisson and Gaussian mixture model. Multiscale conversion is one of the most popular noise reduction methods used in recent years. Estimation of the noise distribution of each subband in the multiscale domain is the most important factor in performing noise reduction, with non-subsampled contourlet transform (NSCT) representing an effective method for scale and direction decomposition. In this study, we use artificially generated noise to analyze and estimate the Poisson-Gaussian noise of low-dose X-ray images in the NSCT domain. The noise distribution of the subband coefficients is analyzed using the noiseless low-band coefficients and the variance of the noisy subband coefficients. The noise-after-transform also follows a Poisson-Gaussian distribution, and the relationship between the noise parameters of the subband and the full-band image is identified. We then analyze noise of actual images to validate the theoretical analysis. Comparison of the proposed noise estimation method with an existing noise reduction method confirms that the proposed method outperforms traditional methods.

Health effects of low dose exposures to external ionizing radiation in the French cohort of nuclear workers CEA-AREVA-EDF - 5287

International Nuclear Information System (INIS)

Leuraud, K.; Fournier, L.; Samson, E.; Caer-Lorho, S.; Laurier, D.; Laroche, P.; Le Guen, B.

2015-01-01

Populations of nuclear workers are particularly relevant to study health effects of low dose and low dose-rate exposures to ionizing radiation. In France, a cohort of nuclear workers employed by CEA, AREVA NC, or EDF, and badge-monitored for radiation exposure, has been followed-up. Annual exposure to penetrating photons was reconstructed for each worker. Standardized mortality ratios were calculated using national mortality rates as the reference. Estimates of radiation dose-mortality associations were obtained using a linear excess relative risk (ERR) model. A total of 59,004 workers were followed-up between 1968 and 2004, for an average of 25 years. The mean cumulative photons dose was 16.1 mSv. At the end of the follow-up, workers were 56 years old and 6,310 workers had died. A strong healthy worker effect was observed. Positive but imprecise estimates of ERR/Sv were observed for all solid cancers and leukemia excluding chronic lymphocytic leukemia. A significant ERR/Sv was found for myeloid leukemia. This cohort study is the most informative ever conducted in France among nuclear workers. Results confirmed a healthy worker effect due to selection at hiring and health monitoring from occupational medicine. Observed dose-risk relationships were consistent with risks estimated in other studies, even if they remained associated to a large uncertainty. (authors)

Noise Estimation for Single-Slice Sinogram of Low-Dose X-Ray Computed Tomography Using Homogenous Patch

Directory of Open Access Journals (Sweden)

Zhiwu Liao

2012-01-01

Full Text Available We present a new method to estimate noise for a single-slice sinogram of low-dose CT based on the homogenous patches centered at a special pixel, called center point, which has the smallest variance among all sinogram pixels. The homogenous patch, composed by homogenous points, is formed by the points similar to the center point using similarity sorting, similarity decreasing searching, and variance analysis in a very large neighborhood (VLN to avoid manual selection of parameter for similarity measures.Homogenous pixels in the VLN allow us find the largest number of samples, who have the highest similarities to the center point, for noise estimation, and the noise level can be estimated according to unbiased estimation.Experimental results show that for the simulated noisy sinograms, the method proposed in this paper can obtain satisfied noise estimation results, especially for sinograms with relatively serious noises.

Predicting standard-dose PET image from low-dose PET and multimodal MR images using mapping-based sparse representation

International Nuclear Information System (INIS)

Wang, Yan; Zhou, Jiliu; Zhang, Pei; An, Le; Ma, Guangkai; Kang, Jiayin; Shi, Feng; Shen, Dinggang; Wu, Xi; Lalush, David S; Lin, Weili

2016-01-01

Positron emission tomography (PET) has been widely used in clinical diagnosis for diseases and disorders. To obtain high-quality PET images requires a standard-dose radionuclide (tracer) injection into the human body, which inevitably increases risk of radiation exposure. One possible solution to this problem is to predict the standard-dose PET image from its low-dose counterpart and its corresponding multimodal magnetic resonance (MR) images. Inspired by the success of patch-based sparse representation (SR) in super-resolution image reconstruction, we propose a mapping-based SR (m-SR) framework for standard-dose PET image prediction. Compared with the conventional patch-based SR, our method uses a mapping strategy to ensure that the sparse coefficients, estimated from the multimodal MR images and low-dose PET image, can be applied directly to the prediction of standard-dose PET image. As the mapping between multimodal MR images (or low-dose PET image) and standard-dose PET images can be particularly complex, one step of mapping is often insufficient. To this end, an incremental refinement framework is therefore proposed. Specifically, the predicted standard-dose PET image is further mapped to the target standard-dose PET image, and then the SR is performed again to predict a new standard-dose PET image. This procedure can be repeated for prediction refinement of the iterations. Also, a patch selection based dictionary construction method is further used to speed up the prediction process. The proposed method is validated on a human brain dataset. The experimental results show that our method can outperform benchmark methods in both qualitative and quantitative measures. (paper)

Risk assessment from heterogeneous energy deposition in tissue, the problem of effects from low doses of ionizing radiation

International Nuclear Information System (INIS)

Feinendegen, L.E.; Booz, J.

1992-01-01

Low doses of ionizing radiation from external or internal sources cause heterogeneous distribution of energy deposition events in the exposed biological system. With the cell being the individual element of the tissue system, the fraction of cells hit, the dose received by the hit, and the biological response of the cell to the dose received eventually determine the effect in tissue. The hit cell may experience detriment, such as change in its DNA leading to a malignant transformation, or it may derive benefit in terms of an adaptive response such as a temporary improvement of DNA repair or temporary prevention of effects from intracellular radicals through enhanced radical detoxification. These responses are protective also to toxic substances that are generated during normal metabolism. Within a multicellular system the probability of detriment must be weighed against the probability of benefit through adaptive responses with protection against various toxic agents including those produced by normal metabolism. Because irradiation can principally induce both, detriment and adaptive responses, one type of affected cells may not be simply summed up at the expense of cells with other types of effects, in assessing risk to tissue. An inventory of various types of effects in the blood-forming system of mammals, even with large ranges of uncertainty, uncovers the possibility of benefit to the system from exposure to low doses of low-LET radiation. This experimental approach may complement epidemiological data on individuals exposed to low doses of ionizing radiation and may lead to a more rational appraisal of risk

Development of cancer risk estimates from epidemiologic studies

International Nuclear Information System (INIS)

Webster, E.W.

1983-01-01

Radiation risk estimates may be made for an increase in mortality from, or for an increase in incidence of, particular types of disease. For both endpoints, two numerical systems of risk expression are used: the absolute risk system (usually the excess deaths or cases per million persons per year per rad), and the relative risk system (usually excess deaths or cases per year per rad expressed as a percentage of those normally expected). Risks may be calculated for specific age groups or for a general population. An alternative in both risk systems is the estimation of cumulative of lifetime risk rather than annual risk (e.g. in excess deaths per million per rad over a specified long period including the remainder of lifespan). The derivation of both absolute and relative risks is illustrated by examples. The effects on risk estimates of latent period, follow-up time, age at exposure and age standardization within dose groups are illustrated. The dependence of the projected cumulative (lifetime) risk on the adoption of a constant absolute risk or constant relative risk is noted. The use of life-table data in the adjustment of cumulative risk for normal mortality following single or annual doses is briefly discussed

Thyroid neoplasia following low-dose radiation in childhood

International Nuclear Information System (INIS)

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

1989-01-01

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

Dose estimate for personal music players including earphone sensitivity and characteristic

DEFF Research Database (Denmark)

Hammershøi, Dorte; Ordoñez Pizarro, Rodrigo Eduardo; Christensen, Anders Tornvig

2016-01-01

Personal music players can expose their listeners to high sound pressure levels over prolonged periods of time. The risk associated with prolonged listening is not readily available to the listener, and efforts are made to standardize dose estimates that may be displayed for the user. In the pres......Personal music players can expose their listeners to high sound pressure levels over prolonged periods of time. The risk associated with prolonged listening is not readily available to the listener, and efforts are made to standardize dose estimates that may be displayed for the user...... earphone measurements published in the past. The work is on-going....

The European initiative on low-dose risk research: from the HLEG to MELODI

International Nuclear Information System (INIS)

Belli, Mauro; Tabocchini, Maria Antonella; Jourdain, Jean-Rene; Repussard, Jacques; Salomaa, Sisko

2015-01-01

The importance of low-dose risk research for radiation protection is now widely recognised. The European Commission (EC) and five European Union (EU) Member States involved in the Euratom Programme set up in 2008 a 'High Level and Expert Group on European Low Dose Risk Research' (HLEG) aimed at identifying research needs and proposing a better integration of European efforts in the field. The HLEG revised the research challenges and proposed a European research strategy based on a 'Multidisciplinary European Low Dose Initiative' (MELODI). In April 2009, five national organisations, with the support of the EC, created the initial core of MELODI (http://www.melodi-online.eu) with a view to integrate the EU institutions with significant programmes in the field, while being open to other scientific organisations and stakeholders, and to develop an agreed strategic research agenda (SRA) and roadmap. Since then, open workshops have been organised yearly, exploring ideas for SRA implementation. As of October 2014, 31 institutions have been included as members of MELODI. HLEG recommendations and MELODI SRA have become important reference points in the radiation protection part of the Euratom Research Programme. MELODI has established close interactions through Memorandum of Understanding with other European platforms involved in radiation protection (Alliance, NERIS and EURADOS) and, together with EURADOS, with the relevant medical European Associations. The role of Joint Programming in priority setting, foreseen in the forthcoming EU Horizon 2020, calls for keeping MELODI an open, inclusive and transparent initiative, able to avoid redundancies and possible conflicts of interest, while promoting common initiatives in radiation protection research. An important issue is the establishment of a proper methodology for managing these initiatives, and this includes the set-up of an independent MELODI Scientific Committee recently extended to Alliance, NERIS

The European initiative on low-dose risk research: from the HLEG to MELODI.

Science.gov (United States)

Belli, Mauro; Tabocchini, Maria Antonella; Jourdain, Jean-René; Salomaa, Sisko; Repussard, Jacques

2015-09-01

The importance of low-dose risk research for radiation protection is now widely recognised. The European Commission (EC) and five European Union (EU) Member States involved in the Euratom Programme set up in 2008 a 'High Level and Expert Group on European Low Dose Risk Research' (HLEG) aimed at identifying research needs and proposing a better integration of European efforts in the field. The HLEG revised the research challenges and proposed a European research strategy based on a 'Multidisciplinary European LOw Dose Initiative' (MELODI). In April 2009, five national organisations, with the support of the EC, created the initial core of MELODI (http://www.melodi-online.eu) with a view to integrate the EU institutions with significant programmes in the field, while being open to other scientific organisations and stakeholders, and to develop an agreed strategic research agenda (SRA) and roadmap. Since then, open workshops have been organised yearly, exploring ideas for SRA implementation. As of October 2014, 31 institutions have been included as members of MELODI. HLEG recommendations and MELODI SRA have become important reference points in the radiation protection part of the Euratom Research Programme. MELODI has established close interactions through Memorandum of Understanding with other European platforms involved in radiation protection (Alliance, NERIS and EURADOS) and, together with EURADOS, with the relevant medical European Associations. The role of Joint Programming in priority setting, foreseen in the forthcoming EU Horizon 2020, calls for keeping MELODI an open, inclusive and transparent initiative, able to avoid redundancies and possible conflicts of interest, while promoting common initiatives in radiation protection research. An important issue is the establishment of a proper methodology for managing these initiatives, and this includes the set-up of an independent MELODI Scientific Committee recently extended to Alliance, NERIS and EURADOS, with

Low doses effects and gamma radiations low dose rates

International Nuclear Information System (INIS)

Averbeck, D.

1999-01-01

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.)

Mammalian Tissue Response to Low Dose Ionizing Radiation: The Role of Oxidative Metabolism and Intercellular Communication

Energy Technology Data Exchange (ETDEWEB)

Azzam, Edouard I

2013-01-16

The objective of the project was to elucidate the mechanisms underlying the biological effects of low dose/low dose rate ionizing radiation in organs/tissues of irradiated mice that differ in their susceptibility to ionizing radiation, and in human cells grown under conditions that mimic the natural in vivo environment. The focus was on the effects of sparsely ionizing cesium-137 gamma rays and the role of oxidative metabolism and intercellular communication in these effects. Four Specific Aims were proposed. The integrated outcome of the experiments performed to investigate these aims has been significant towards developing a scientific basis to more accurately estimate human health risks from exposures to low doses ionizing radiation. By understanding the biochemical and molecular changes induced by low dose radiation, several novel markers associated with mitochondrial functions were identified, which has opened new avenues to investigate metabolic processes that may be affected by such exposure. In particular, a sensitive biomarker that is differentially modulated by low and high dose gamma rays was discovered.

Biological effects of low-dose ionizing radiation exposure

International Nuclear Information System (INIS)

Reinoehl-Kompa, Sabine; Baldauf, Daniela; Heller, Horst

2009-01-01

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.

Dose rate estimation of the Tohoku hynobiid salamander, Hynobius lichenatus, in Fukushima.

Science.gov (United States)

Fuma, Shoichi; Ihara, Sadao; Kawaguchi, Isao; Ishikawa, Takahiro; Watanabe, Yoshito; Kubota, Yoshihisa; Sato, Youji; Takahashi, Hiroyuki; Aono, Tatsuo; Ishii, Nobuyoshi; Soeda, Haruhi; Matsui, Kumi; Une, Yumi; Minamiya, Yukio; Yoshida, Satoshi

2015-05-01

studies of the adult salamanders may be required in order to examine whether the most severe radioactive contamination has any effects on sensitive endpoints, since the estimated highest dose rate to the adults exceeded some of the guidance dose rates proposed by various organisations and programmes for the protection of amphibians, which range from 4 to 400 μGy h(-1). Conversely, at one site in Nakadori, a moderately contaminated region in Fukushima Prefecture, the dose rate to the adult salamanders in spring of 2012 was estimated to be 0.2 μGy h(-1). Estimated dose rates to the overwintering larvae in spring of 2012 were 1 and 0.2 μGy h(-1) at one site in Nakadori, and in Aizu, a less contaminated region in Fukushima Prefecture, respectively. These results suggest that there is a low risk that H. lichenatus will be affected by radioactive contamination in these districts, though further studies on dose rate estimation are required for definitive risk characterisation. Copyright © 2015 Elsevier Ltd. All rights reserved.

Low-dose aspirin and risk of intracranial bleeds

DEFF Research Database (Denmark)

Cea Soriano, Lucía; Gaist, David; Soriano-Gabarró, Montse

2017-01-01

cohort of nonusers of low-dose aspirin at baseline were followed (maximum 14 years, median 5.4 years) to identify incident cases of ICB, with validation by manual review of patient records or linkage to hospitalization data. Using 10,000 frequency-matched controls, adjusted rate ratios (RRs) with 95...

Estimates of radiation doses in tissue and organs and risk of excess cancer in the single-course radiotherapy patients treated for ankylosing spondylitis in England and Wales

International Nuclear Information System (INIS)

Fabrikant, J.I.; Lyman, J.T.

1982-02-01

The estimates of absorbed doses of x rays and excess risk of cancer in bone marrow and heavily irradiated sites are extremely crude and are based on very limited data and on a number of assumptions. Some of these assumptions may later prove to be incorrect, but it is probable that they are correct to within a factor of 2. The excess cancer risk estimates calculated compare well with the most reliable epidemiological surveys thus far studied. This is particularly important for cancers of heavily irradiated sites with long latent periods. The mean followup period for the patients was 16.2 y, and an increase in cancers of heavily irradiated sites may appear in these patients in the 1970s in tissues and organs with long latent periods for the induction of cancer. The accuracy of these estimates is severely limited by the inadequacy of information on doses absorbed by the tissues at risk in the irradiated patients. The information on absorbed dose is essential for an accurate assessment of dose-cancer incidence analysis. Furthermore, in this valuable series of irradiated patients, the information on radiation dosimetry on the radiotherapy charts is central to any reliable determination of somatic risks of radiation with regard to carcinogenesis in man. The work necessary to obtain these data is under way; only when they are available can more precise estimates of risk of cancer induction by radiation in man be obtained

Weldon Spring historical dose estimate

International Nuclear Information System (INIS)

Meshkov, N.; Benioff, P.; Wang, J.; Yuan, Y.

1986-07-01

This study was conducted to determine the estimated radiation doses that individuals in five nearby population groups and the general population in the surrounding area may have received as a consequence of activities at a uranium processing plant in Weldon Spring, Missouri. The study is retrospective and encompasses plant operations (1957-1966), cleanup (1967-1969), and maintenance (1969-1982). The dose estimates for members of the nearby population groups are as follows. Of the three periods considered, the largest doses to the general population in the surrounding area would have occurred during the plant operations period (1957-1966). Dose estimates for the cleanup (1967-1969) and maintenance (1969-1982) periods are negligible in comparison. Based on the monitoring data, if there was a person residing continually in a dwelling 1.2 km (0.75 mi) north of the plant, this person is estimated to have received an average of about 96 mrem/yr (ranging from 50 to 160 mrem/yr) above background during plant operations, whereas the dose to a nearby resident during later years is estimated to have been about 0.4 mrem/yr during cleanup and about 0.2 mrem/yr during the maintenance period. These values may be compared with the background dose in Missouri of 120 mrem/yr

Weldon Spring historical dose estimate

Energy Technology Data Exchange (ETDEWEB)

Meshkov, N.; Benioff, P.; Wang, J.; Yuan, Y.

1986-07-01

This study was conducted to determine the estimated radiation doses that individuals in five nearby population groups and the general population in the surrounding area may have received as a consequence of activities at a uranium processing plant in Weldon Spring, Missouri. The study is retrospective and encompasses plant operations (1957-1966), cleanup (1967-1969), and maintenance (1969-1982). The dose estimates for members of the nearby population groups are as follows. Of the three periods considered, the largest doses to the general population in the surrounding area would have occurred during the plant operations period (1957-1966). Dose estimates for the cleanup (1967-1969) and maintenance (1969-1982) periods are negligible in comparison. Based on the monitoring data, if there was a person residing continually in a dwelling 1.2 km (0.75 mi) north of the plant, this person is estimated to have received an average of about 96 mrem/yr (ranging from 50 to 160 mrem/yr) above background during plant operations, whereas the dose to a nearby resident during later years is estimated to have been about 0.4 mrem/yr during cleanup and about 0.2 mrem/yr during the maintenance period. These values may be compared with the background dose in Missouri of 120 mrem/yr.

The role of uncertainty analysis in dose reconstruction and risk assessment

International Nuclear Information System (INIS)

Hoffman, F.O.; Simon, S.L.; Thiessen. K.M.

1996-01-01

Dose reconstruction and risk assessment rely heavily on the use of mathematical models to extrapolate information beyond the realm of direct observation. Because models are merely approximations of real systems, their predictions are inherently uncertain. As a result, full disclosure of uncertainty in dose and risk estimates is essential to achieve scientific credibility and to build public trust. The need for formal analysis of uncertainty in model predictions was presented during the nineteenth annual meeting of the NCRP. At that time, quantitative uncertainty analysis was considered a relatively new and difficult subject practiced by only a few investigators. Today, uncertainty analysis has become synonymous with the assessment process itself. When an uncertainty analysis is used iteratively within the assessment process, it can guide experimental research to refine dose and risk estimates, deferring potentially high cost or high consequence decisions until uncertainty is either acceptable or irreducible. Uncertainty analysis is now mandated for all ongoing dose reconstruction projects within the United States, a fact that distinguishes dose reconstruction from other types of exposure and risk assessments. 64 refs., 6 figs., 1 tab

Biochemical and cellular mechanisms of low-dose effects

International Nuclear Information System (INIS)

Feinendegen, L.E.; Booz, J.; Muehlensiepen, H.

1988-01-01

The question of health effects from small radiation doses remains open. Individual cells, when being hit by single elemental doses - in low-dose irradiation - react acutely and temporarily by altering control of enzyme activity, as is demonstrated for the case of thymidine kinase. This response is not constant in that it provides a temporary protection of enzyme activity against a second irradiation, by a mechanism likely to be via improved detoxification of intracellular radicals. It must be considered that in the low-dose region radiation may also exert protection against other challenges involving radicals, causing a net beneficial effect by temporarily shielding the hit cell against radicals produced by metabolism. Since molecular alterations leading to late effects are considered a consequence of the initial cellular response, late effects from small radiation doses do not necessarily adhere to a linear dose-effect relationship. The reality of the linear relationship between the risk of late effects from high doses to small doses is an assumption, for setting dose limits, but it must not be taken for predicting health detriment from low doses. (author)

Low dose radiation and ALARA: the potential risks to patients and staff from alpha-therapy

International Nuclear Information System (INIS)

Priest, N.D.

2014-01-01

This year a new drug containing radium-223, an alpha-emitting radionuclide, was approved for use by the US Food and Drug Administration for the palliative treatment of advanced prostate cancer metastases. Other drugs containing short-lived alpha-emitters are on clinical trial in Europe. Commonly, these employ a radionuclide attached to an antibody that specifically targets tumor cells to produce a highly localized radio-therapeutic dose to the tumor. However, normal tissues within the body will also be irradiated, albeit sometimes at low dose, and the question arises as to whether this presents a significant additional risk to the patient. Similarly, medical staff that handle these radionuclides could receive intakes of the radionuclides. What is the risk to staff? To assess the risk resulting from small tissue alpha-doses the toxicological, both human and animal, database was re-examined. The results of 20 epidemiological and toxicological studies with alpha-emitting radionuclides were analysed. In all cases a polynomial function provided a better fit to the data than a linear, no thresholds function. Also, in 19 cases a threshold dose below which no cancer is seen was indicated. The position of this threshold varied according to cancer type, but was typically in the range 0.1 to 1.0Gy of tissue dose - with a mean of 0.5Gy. It is concluded that alpha-radiation induced tumorogenesis is a threshold response and that as long as tissue doses are kept below these thresholds no additional cancers would be seen in either patients receiving alpha-therapy or in staff exposed to 'spilt' radionuclide. The presence of thresholds questions the appropriateness of current ALARA practices that are mostly used to drive occupational alpha-radiation exposures to as close to zero as possible. (author)

Low dose radiation and ALARA: the potential risks to patients and staff from alpha-therapy

Energy Technology Data Exchange (ETDEWEB)

Priest, N.D. [Atomic Energy of Canada Limited, Chalk River, ON (Canada)

2014-07-01

This year a new drug containing radium-223, an alpha-emitting radionuclide, was approved for use by the US Food and Drug Administration for the palliative treatment of advanced prostate cancer metastases. Other drugs containing short-lived alpha-emitters are on clinical trial in Europe. Commonly, these employ a radionuclide attached to an antibody that specifically targets tumor cells to produce a highly localized radio-therapeutic dose to the tumor. However, normal tissues within the body will also be irradiated, albeit sometimes at low dose, and the question arises as to whether this presents a significant additional risk to the patient. Similarly, medical staff that handle these radionuclides could receive intakes of the radionuclides. What is the risk to staff? To assess the risk resulting from small tissue alpha-doses the toxicological, both human and animal, database was re-examined. The results of 20 epidemiological and toxicological studies with alpha-emitting radionuclides were analysed. In all cases a polynomial function provided a better fit to the data than a linear, no thresholds function. Also, in 19 cases a threshold dose below which no cancer is seen was indicated. The position of this threshold varied according to cancer type, but was typically in the range 0.1 to 1.0Gy of tissue dose - with a mean of 0.5Gy. It is concluded that alpha-radiation induced tumorogenesis is a threshold response and that as long as tissue doses are kept below these thresholds no additional cancers would be seen in either patients receiving alpha-therapy or in staff exposed to 'spilt' radionuclide. The presence of thresholds questions the appropriateness of current ALARA practices that are mostly used to drive occupational alpha-radiation exposures to as close to zero as possible. (author)

Radiation quality and effective dose equivalent of alpha particles from radon decay products indoors: uncertainties in risk estimation

Energy Technology Data Exchange (ETDEWEB)

Al-Affan, I.A. (Velindre Hospital, Whitchurch, Cardiff (United Kingdom))

1994-01-01

In order to make a better estimate of cancer risk due to radon the radiation quality of alpha particles emitted from the element and its daughters has been re-assessed. In particular, uncertainties in all components involved in the calculations of the effective dose E, have been investigated. This has been done in the light of the recent draft report of the ICRU on quantities and units for use in radiation protection (Allisy et al (1991) ICRU NEWS 2). On the assumption of an indoor radon concentration of 30 Bq.m[sup -3], microdose spectra have been calculated for alpha particles hitting lung cells at different depths. Then the mean quality factor Q-bar in the lung, dose equivalent H[sub T] to the lung and the effective dose have been calculated. A comparison between lung cancer risk from radon and that arising from diagnostic X rays to the chest is made. A suggestion to make the lung weighting factor w[sub T] a function of the fraction of lung cells hit is discussed. (Author).

Low-dose computed tomography image restoration using previous normal-dose scan

International Nuclear Information System (INIS)

Ma, Jianhua; Huang, Jing; Feng, Qianjin; Zhang, Hua; Lu, Hongbing; Liang, Zhengrong; Chen, Wufan

2011-01-01

Purpose: In current computed tomography (CT) examinations, the associated x-ray radiation dose is of a significant concern to patients and operators. A simple and cost-effective means to perform the examinations is to lower the milliampere-seconds (mAs) or kVp parameter (or delivering less x-ray energy to the body) as low as reasonably achievable in data acquisition. However, lowering the mAs parameter will unavoidably increase data noise and the noise would propagate into the CT image if no adequate noise control is applied during image reconstruction. Since a normal-dose high diagnostic CT image scanned previously may be available in some clinical applications, such as CT perfusion imaging and CT angiography (CTA), this paper presents an innovative way to utilize the normal-dose scan as a priori information to induce signal restoration of the current low-dose CT image series. Methods: Unlike conventional local operations on neighboring image voxels, nonlocal means (NLM) algorithm utilizes the redundancy of information across the whole image. This paper adapts the NLM to utilize the redundancy of information in the previous normal-dose scan and further exploits ways to optimize the nonlocal weights for low-dose image restoration in the NLM framework. The resulting algorithm is called the previous normal-dose scan induced nonlocal means (ndiNLM). Because of the optimized nature of nonlocal weights calculation, the ndiNLM algorithm does not depend heavily on image registration between the current low-dose and the previous normal-dose CT scans. Furthermore, the smoothing parameter involved in the ndiNLM algorithm can be adaptively estimated based on the image noise relationship between the current low-dose and the previous normal-dose scanning protocols. Results: Qualitative and quantitative evaluations were carried out on a physical phantom as well as clinical abdominal and brain perfusion CT scans in terms of accuracy and resolution properties. The gain by the use

Estimation of enhanced cancer risk with 18FDG PET/CT investigations

International Nuclear Information System (INIS)

Kaushik, Aruna; Mishra, Anil K.; Sharma, Rajnish; Mondal, Anupam; Dwarakanath, B.S.

2014-01-01

18 F-Fluorodeoxyglucose ( 18 FDG) Positron Emission Tomography/Computed Tomography (PET/CT) investigation involves internal administration of 18 FDG and use of CT X-rays for the purpose of obtaining functional and anatomical information of a patient. However, the radiation exposure from undergoing PET/CT investigation may enhance the risk of cancer incidence as per the Linear-No-Threshold (LNT) model. The objective of the present study was to quantify the risk of cancer incidence associated with radiation exposure from 18 FDG PET/CT investigations. The organ doses from internally administered 18 FDG were estimated using OLINDA/EXM Code by performing dynamic PET scans in different regions of the body in a total of forty-nine patients. Organ doses from the CT component were calculated using the software CT-Expo. The associated cancer risk was calculated in terms of life time risk of cancer incidence resulting from a specified dose of ionizing radiation and was expressed in terms of Lifetime Attributable Risk (LAR). LAR values and the organ doses estimated for males and females were used to estimate the lifetime risk of cancer incidence from whole body 18 FDG PET/CT scan. Since from 18 FDG whole body PET/CT investigations, various tissues of the body receive substantially different doses, the site specific risk of cancer incidence was estimated and summed to obtain the total risk. This was compared with the baseline lifetime risk of cancer incidence in Indian population. LAR of cancer incidence was observed to be relatively higher in females as compared to males. The risk estimates ranged from 0.36% to 0.49% for a 20 year old male and 0.58% to 0.79% for a 20 year old female and were observed to be higher in younger ages and decreased with age. 18 FDG whole body PET/CT investigation was observed to be associated with non-negligible radiation risk as compared to the risks associated with other diagnostic modalities. (author)

Risk equivalent of exposure versus dose of radiation

International Nuclear Information System (INIS)

Bond, V.P.

1986-01-01

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

The Radiobiological Basis for Improvements in Radiotherapy and Low Dose Risk Assessment

Energy Technology Data Exchange (ETDEWEB)

Hei, Tom K. [Columbia Univ., New York, NY (United States)

2009-12-09

This conference grant was proposed to organize and host an international conference at Columbia University in New York to critically assess the cellular and molecular signaling events and tissue response following radiation damage. The conference would also serve as a venue to play tribute to the more than forty years contributions made by Professor Eric J. Hall to the radiation biology field. The goals of the meeting were to examine tumor hypoxia and sensitizer development; recent advances made in clinical radiotherapy; addressed several low dose phenomena, including genomic instability and bystander effects that are important in radiation risk assessment. Study and Results: The symposium was held on October 13th and 14th, 2008 at the Alfred Lerner Hall in the Morningside campus of Columbia University. The symposium, entitled “From Beans to Genes: A Forty Year Odyssey in Radiation Biology” was attended by more than 120 faculty, scientists, clinicians, fellows and students. The symposium, spanned over a day and a half, covered four scientific themes. These included tumor hypoxia and radiosensitizers; low dose radiation response; radiation biology in the practice of radiotherapy, and radiation hazard in space and genetic predisposition to cancer. The program of the symposium is as follow:

Mutation induction in cultured human cells after low-dose and low-dose-rate γ-ray irradiation. Detection by LOH analysis

International Nuclear Information System (INIS)

Umebayashi, Yukihiro; Iwaki, Masaya; Yatagai, Fumio; Honma, Masamitsu; Suzuki, Masao; Suzuki, Hiromi; Shimazu, Toru; Ishioka, Noriaki

2007-01-01

To study the genetic effects of low-doses and low-dose-rate ionizing radiation (IR), human lymphoblastoid TK6 cells were exposed to 30 mGy of γ-rays at a dose-rate of 1.2 mGy/hr. The frequency of early mutations (EMs) in the thymidine kinase (TK) gene locus was determined to be 1.7 x 10 -6 , or 1.9-fold higher than the level seen in unirradiated controls. These mutations were analyzed with a loss of heterozygosity (LOH) detection system, a methodology which has been shown to be sensitive to the effects of radiation. Among the 15 EMs observed after IR exposure, 8 were small interstitial-deletion events restricted to the TK gene locus. However, this specific type of event was not found in unirradiated controls. Although these results were observed under the limited conditions, they strongly suggest that the LOH detection system can be used for estimating the genetic effects of a low-dose IR exposure delivered at a low-dose-rate. (author)

Statistical and low dose response

International Nuclear Information System (INIS)

Thorson, M.R.; Endres, G.W.R.

1981-01-01

The low dose response and the lower limit of detection of the Hanford dosimeter depend upon may factors, including the energy of the radiation, whether the exposure is to be a single radiation or mixed fields, annealing cycles, environmental factors, and how well various batches of TLD materials are matched in the system. A careful statistical study and sensitivity analysis were performed to determine how these factors influence the response of the dosimeter system. Estimates have been included in this study of the standard deviation of calculated dose for various mixed field exposures from 0 to 1000 mrem

Absorbed Doses and Risk Estimates of (211)At-MX35 F(ab')2 in Intraperitoneal Therapy of Ovarian Cancer Patients

DEFF Research Database (Denmark)

Cederkrantz, Elin; Andersson, Håkan; Bernhardt, Peter

2015-01-01

dose associated with i.p. administration of (211)At-MX35 F(ab')2. METHODS AND MATERIALS: Patients in clinical remission after salvage chemotherapy for peritoneal recurrence of ovarian cancer underwent i.p. infusion of (211)At-MX35 F(ab')2. Potassium perchlorate was given to block unwanted accumulation...... 100 MBq/L, organ equivalent doses were less than 10% of the estimated tolerance dose. CONCLUSION: Intraperitoneal (211)At-MX35 F(ab')2 treatment is potentially a well-tolerated therapy for locally confined microscopic ovarian cancer. Absorbed doses to normal organs are low, but because the effective...

The estimation of radiation effective dose from diagnostic medical procedures in general population of northern Iran

International Nuclear Information System (INIS)

Shabestani Monfared, A.; Abdi, R.

2006-01-01

The risks of low-dose Ionizing radiation from radiology and nuclear medicine are not clearly determined. Effective dose to population is a very important factor in risk estimation. The study aimed to determine the effective dose from diagnostic radiation medicine in a northern province of Iran. Materials and Methods: Data about various radiologic and nuclear medicine procedures were collected from all radiology and nuclear medicine departments In Mazandaran Province (population = 2,898,031); and using the standard dosimetry tables, the total dose, dose per examination, and annual effective dose per capita as well as the annual gonadal dose per capita were estimated. Results: 655,730 radiologic examinations in a year's period, lead to 1.45 mSv, 0.33 mSv and 0.31 mGy as average effective dose per examination, annual average effective dose to member of the public, and annual average gonadal dose per capita, respectively. The frequency of medical radiologic examinations was 2,262 examinations annually per 10,000 members of population. However, the total number of nuclear medicine examinations in the same period was 7074, with 4.37 mSv, 9.6 μSv and 9.8 μGy, as average effective dose per examination, annual average effective dose to member of the public and annual average gonadal dose per caput, respectively. The frequency of nuclear medicine examination was 24 examinations annually per 10,000 members of population. Conclusion: The average effective dose per examination was nearly similar to other studies. However, the average annual effective dose and annual average gonadal dose per capita were less than the similar values in other reports, which could be due to lesser number of radiation medicine examinations in the present study

Exposures at low doses and biological effects of ionizing radiations

International Nuclear Information System (INIS)

Masse, R.

2000-01-01

Everyone is exposed to radiation from natural, man-made and medical sources, and world-wide average annual exposure can be set at about 3.5 mSv. Exposure to natural sources is characterised by very large fluctuations, not excluding a range covering two orders of magnitude. Millions of inhabitants are continuously exposed to external doses as high as 10 mSv per year, delivered at low dose rates, very few workers are exposed above the legal limit of 50 mSv/year, and referring to accidental exposures, only 5% of the 116 000 people evacuated following the Chernobyl disaster encountered doses above 100 mSv. Epidemiological survey of accidentally, occupationally or medically exposed groups have revealed radio-induced cancers, mostly following high dose-rate exposure levels, only above 100 mSv. Risk coefficients were derived from these studies and projected into linear models of risk (linear non-threshold hypothesis: LNT), for the purpose of risk management following exposures at low doses and low dose-rates. The legitimacy of this approach has been questioned, by the Academy of sciences and the Academy of medicine in France, arguing: that LNT was not supported by Hiroshima and Nagasaki studies when neutron dose was revisited; that linear modelling failed to explain why so many site-related cancers were obviously nonlinearly related to the dose, and especially when theory predicted they ought to be; that no evidence could be found of radio-induced cancers related to natural exposures or to low exposures at the work place; and that no evidence of genetic disease could be shown from any of the exposed groups. Arguments were provided from cellular and molecular biology helping to solve this issue, all resulting in dismissing the LNT hypothesis. These arguments included: different mechanisms of DNA repair at high and low dose rate; influence of inducible stress responses modifying mutagenesis and lethality; bystander effects allowing it to be considered that individual

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

International Nuclear Information System (INIS)

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

2003-01-01

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

European Collaboration on Low-dose Aspirin in Polycythemia Vera (ECLAP): a randomized trial.

Science.gov (United States)

Landolfi, R; Marchioli, R

1997-01-01

Thrombotic complications characterize the clinical course of polycythemia vera (PV) and represent the main cause of morbidity and mortality. However, uncertainty still exists as to the benefit/risk ratio of aspirin prophylaxis in this setting. In vivo platelet biosynthesis of thromboxane A2 is enhanced and can be suppressed by low-dose aspirin in PV, thus providing a rationale for assessing the efficacy and safety of a low-dose aspirin regimen in these patients. The Gruppo Italiano Studio Policitemia Vera has recently performed a pilot study on 112 patients randomized to receive aspirin, 40 mg daily, or placebo and followed for 16 +/- 6 months (mean +/- SD). This study showed that low-dose aspirin is well tolerated in PV patients, and that a large-scale efficacy trial is feasible in this setting. In this article we report the protocol of the European Collaboration on Low-dose Aspirin in Polycythemia Vera (ECLAP) study, which is a randomized trial designed to assess the risk/benefit ratio of low-dose aspirin in PV. To estimate the size and the follow-up duration required for the ECLAP trial, a retrospective analysis of the clinical epidemiology of a large PV population has recently been completed by the Gruppo Italiano Studio Policitemia Vera. On this basis, approximately 3500 patients will be enrolled in the ECLAP study with a follow-up of 3 to 4 years. The uncertainty principle will be used as the main eligibility criterion: Polycythemic patients of any age, having no clear indication for or contraindication to aspirin treatment, will be randomized in a double-blind fashion to receive oral aspirin (100 mg daily) or placebo. According to current therapeutic recommendations, the basic treatment of randomized patients should be aimed at maintaining the hematocrit value 50. Randomization will be stratified by participating center. The study is funded by the European Union BIOMED 2 program.

Deep learning for low-dose CT

Science.gov (United States)

Chen, Hu; Zhang, Yi; Zhou, Jiliu; Wang, Ge

2017-09-01

Given the potential risk of X-ray radiation to the patient, low-dose CT has attracted a considerable interest in the medical imaging field. Currently, the main stream low-dose CT methods include vendor-specific sinogram domain filtration and iterative reconstruction algorithms, but they need to access raw data whose formats are not transparent to most users. Due to the difficulty of modeling the statistical characteristics in the image domain, the existing methods for directly processing reconstructed images cannot eliminate image noise very well while keeping structural details. Inspired by the idea of deep learning, here we combine the autoencoder, deconvolution network, and shortcut connections into the residual encoder-decoder convolutional neural network (RED-CNN) for low-dose CT imaging. After patch-based training, the proposed RED-CNN achieves a competitive performance relative to the-state-of-art methods. Especially, our method has been favorably evaluated in terms of noise suppression and structural preservation.

Consideration of the usefulness of a size-specific dose estimate in pediatric CT examination.

Science.gov (United States)

Tsujiguchi, Takakiyo; Obara, Hideki; Ono, Shuichi; Saito, Yoko; Kashiwakura, Ikuo

2018-04-05

Computed tomography (CT) has recently been utilized in various medical settings, and technological advances have resulted in its widespread use. However, medical radiation exposure associated with CT scans accounts for the largest share of examinations using radiation; thus, it is important to understand the organ dose and effective dose in detail. The CT dose index and dose-length product are used to evaluate the organ dose. However, evaluations using these indicators fail to consider the age and body type of patients. In this study, we evaluated the effective dose based on the CT examination data of 753 patients examined at our hospital using the size-specific dose estimate (SSDE) method, which can calculate the exposure dose with consideration of the physique of a patient. The results showed a large correlation between the SSDE conversion factor and physique, with a larger exposure dose in patients with a small physique when a single scan is considered. Especially for children, the SSDE conversion factor was found to be 2 or more. In addition, the patient exposed to the largest dose in this study was a 10-year-old, who received 40.4 mSv (five series/examination). In the future, for estimating exposure using the SSDE method and in cohort studies, the diagnostic reference level of SSDE should be determined and a low-exposure imaging protocol should be developed to predict the risk of CT exposure and to maintain the quality of diagnosis with better radiation protection of patients.

Are risk estimates biased in follow-up studies of psychosocial factors with low base-line participation?

Directory of Open Access Journals (Sweden)

Andersen Johan

2011-07-01

Full Text Available Abstract Background Low participation in population-based follow-up studies addressing psychosocial risk factors may cause biased estimation of health risk but the issue has seldom been examined. We compared risk estimates for selected health outcomes among respondents and the entire source population. Methods In a Danish cohort study of associations between psychosocial characteristics of the work environment and mental health, the source population of public service workers comprised 10,036 employees in 502 work units of which 4,489 participated (participation rate 45%. Data on the psychosocial work environment were obtained for each work unit by calculating the average of the employee self-reports. The average values were assigned all employees and non-respondent at the work unit. Outcome data on sick leave and prescription of antidepressant medication during the follow-up period (1.4.2007-31.12.2008 was obtained by linkage to national registries. Results Respondents differed at baseline from non-respondents by gender, age, employment status, sick leave and hospitalization for affective disorders. However, risk estimates for sick leave and prescription of antidepressant medication, during follow-up, based on the subset of participants, did only differ marginally from risk estimates based upon the entire population. Conclusions We found no indications that low participation at baseline distorts the estimates of associations between the work unit level of psychosocial work environment and mental health outcomes during follow-up. These results may not be valid for other exposures or outcomes.

Attributability of health effects at low radiation doses

International Nuclear Information System (INIS)

Gonzalez, Abel

2008-01-01

Full text: A controversy still persists on whether health effects can be alleged from radiation exposure situations involving low radiation doses (e.g. below the international dose limits for the public). Arguments have evolved around the validity of the dose-response representation that is internationally used for radiation protection purposes, namely the so-called linear-non-threshold (LNT) model. The debate has been masked by the intrinsic randomness of radiation interaction at the cellular level and also by gaps in the relevant scientific knowledge on the development and expression of health effects. There has also been a vague use, abuse, and misuse of radiation-related risk concepts and quantities and their associated uncertainties. As a result, there is some ambiguity in the interpretation of the phenomena and a general lack of awareness of the implications for a number of risk-causation qualities, namely its attributes and characteristics. In particular, the LNT model has been used not only for protection purposes but also for blindly attributing actual effects to specific exposure situations. The latter has been discouraged as being a misuse of the model, but the supposed incorrectness has not been clearly proven. The paper will endeavour to demonstrate unambiguously the following thesis in relation to health effects due to low radiation doses: 1) Their existence is highly plausible. A number of epidemiological statistical assessments of sufficiently large exposed populations show that, under certain conditions, the prevalence of the effects increases with dose. From these assessments, it can be hypothesized that the occurrence of the effects at any dose, however small, appears decidedly worthy of belief. While strictly the evidence does not allow to conclude that a threshold dose level does not exist either. In fact, a formal quantitative uncertainty analysis, combining the different uncertain components of estimated radiation-related risk, with and