Ionizing Radiation Research Papers - Academia.edu (original) (raw)

Radiobiologists have been struggling to estimate the health risks from low doses of radiation in humans for decades. Health risks involve not only neoplastic diseases but also somatic mutations that may contribute to other illnesses... more

Radiobiologists have been struggling to estimate the health risks from low doses of radiation in humans for decades. Health risks involve not only neoplastic diseases but also somatic mutations that may contribute to other illnesses (including birth defects and ocular maladies) and heritable mutations that may increase the risk of diseases in future generations. Low dose radiation-induced cancer in humans depends on several variables, and most of these variables are not possible to correct for in any epidemiologic study. Some of the confounding factors include (i) interaction of radiation with other physical (UV light), chemical, and biological mutagens and carcinogens in a synergistic manner; (ii) variation in repair mechanisms that depend on dose; (iii) variation in sensitivity of bystander cells to subsequent radiation exposure that depends on whether they have been pre- or postirradiated; and (iv) variation in adaptive response that depends on radiation doses and protective subs...

A B S T R A C T Recent epidemiology studies highlighted the detrimental health effects of exposure to low dose and low dose rate ionizing radiation (IR): nuclear industry workers studies have shown increased leukaemia and solid tumour... more

A B S T R A C T Recent epidemiology studies highlighted the detrimental health effects of exposure to low dose and low dose rate ionizing radiation (IR): nuclear industry workers studies have shown increased leukaemia and solid tumour risks following cumulative doses of <100 mSv and dose rates of <10 mGy per year; paediatric patients studies have reported increased leukaemia and brain tumours risks after doses of 30–60 mGy from computed tomography scans. Questions arise, however, about the impact of even lower doses and dose rates where classical epidemiological studies have limited power but where subsets within the large cohorts are expected to have an increased risk. Further progress requires integration of biomarkers or bioassays of individual exposure, effects and susceptibility to IR. The European DoReMi (Low Dose Research towards Multidisciplinary Integration) consortium previously reviewed biomarkers for potential use in IR epidemiological studies. Given the increased mechanistic understanding of responses to low dose radiation the current review provides an update covering technical advances and recent studies. A key issue identified is deciding which biomarkers to progress. A roadmap is provided for biomarker development from discovery to implementation and used to summarise the current status of proposed biomarkers for epidemiological studies. Most potential biomarkers remain at the discovery stage and for some there is sufficient evidence that further development is not warranted. One biomarker j o u r n a l h o m e p a g e : w w w. e l s e v i e r. c o m / l o c a t e / r e v i e w s m r C o m m u n i t y a d d r e s s : w w w. e l s e v i e r. c o m / l o c a t e / m u t r e s identified in the final stages of development and as a priority for further research is radiation specific mRNA transcript profiles. Crown

Atmospheric ionizing radiation is of interest, apart from its main concern of aircraft exposures, because it is a principal source of human exposure to radiations with high linear energy transfer (LET). The ionizing radiations of the... more

Atmospheric ionizing radiation is of interest, apart from its main concern of aircraft exposures, because it is a principal source of human exposure to radiations with high linear energy transfer (LET). The ionizing radiations of the lower atmosphere tend to be dominated by the terrestrial radioisotopes especially along the costal plain and interior low lands and have only minor contributions

There is increasing awareness among pediatric radiologists of the potential risks associated with ionizing radiation in medical imaging. However, it is not known whether there has been a corresponding increase in awareness among... more

There is increasing awareness among pediatric radiologists of the potential risks associated with ionizing radiation in medical imaging. However, it is not known whether there has been a corresponding increase in awareness among pediatricians. To establish the level of awareness among pediatricians of the recent publicity on radiation risks in children, knowledge of the relative doses of radiological investigations, current practice regarding parent/patient discussions, and the sources of educational input. Multiple-choice survey. Of 220 respondents, 105 (48%) were aware of the 2001 American Journal of Roentgenology articles on pediatric CT and radiation, though only 6% were correct in their estimate of the quoted lifetime excess cancer risk associated with radiation doses equivalent to pediatric CT. A sustained or transient increase in parent questioning regarding radiation doses had been noticed by 31%. When estimating the effective doses of various pediatric radiological investig...

The purpose of this paper is to assess fatal cancer risk after external and internal (inhalation and ingestion) exposure from natural radionuclides in soil like (238)U, (232)Th, (40)K, and (226)Ra on the territory of Bela Crkva, Serbia.... more

The purpose of this paper is to assess fatal cancer risk after external and internal (inhalation and ingestion) exposure from natural radionuclides in soil like (238)U, (232)Th, (40)K, and (226)Ra on the territory of Bela Crkva, Serbia. Although receiving doses are low from sources like natural radionuclides in soil, because of stochastic effects of ionizing radiation, risk for developing cancer exists and can be quantified. Concentrations of radionuclides from 80 soil samples are measured using HPGe detector. Fatal cancer risk is assessed from calculated ambient dose rate in the target organs of body due to external and internal exposure. Monte Carlo simulations are used to obtain conversion factors which are required to calculate absorbed dose rate in target organs. Assessed cancer risk for (238)U in the case of both inhalation and ingestion exposure is from 1.11 × 10(-6) to 24 × 10(-6) for minimal and maximal activity in soil samples, from 1.02 × 10(-6) to 23.3 × 10(-6) for exposure to (226)Ra, from 1.89 × 10(-6) to 50.3 × 10(-6) for exposure to (232)Th, and from 0.265 × 10(-6) to 9.83 × 10(-6) for exposure to (40)K. Overall risk from (40)K as external and internal source is from 0.8 × 10(-6) to 31.9 × 10(-6). Calculated cancer risks from both inhalation and ingestion exposure could be related to all tissues that are on the way of distribution of particles within the body but especially to deposition sites in the body. Assessed risks for fatal cancer development from inhaled and ingested natural radionuclides originating in soil are not increased.

Knowledge and awareness of physicians and the general public concerning the risks of prenatal exposure to ionizing radiation are important when developing a correct attitude to ionizing radiation. This is particularly important in the... more

Knowledge and awareness of physicians and the general public concerning the risks of prenatal exposure to ionizing radiation are important when developing a correct attitude to ionizing radiation. This is particularly important in the justification of medical diagnostic exposure of pregnant women and in case of possible accidents. The present paper reviews the most recent data on the effects of prenatal exposure to ionizing radiation reported in the scientific literature and in documents of international organizations dealing with this subject. Potentially significant exposure for women of childbearing age in medical diagnostics, working conditions and environmental contamination following the Chernobyl accident are reported. Some examples of doses associated with medical exposure in the course of diagnostic examinations with X-rays and radiopharmaceuticals, and occupational exposure in workplaces are given. Lastly, the regulatory aspects of the European Union directives and the Italian legislation on medical and occupational exposure of women during pregnancy or in reproductive age are reviewed. □Foetal, in utero, ionizing radiation, radiation protection

Phosphorylation of histone protein H2AX on serine 139 (gamma-H2AX) occurs at sites flanking DNA double-stranded breaks (DSBs) and can provide a measure of the number of DSBs within a cell. We describe a flow cytometry-based method... more

Phosphorylation of histone protein H2AX on serine 139 (gamma-H2AX) occurs at sites flanking DNA double-stranded breaks (DSBs) and can provide a measure of the number of DSBs within a cell. We describe a flow cytometry-based method optimized to measure gamma-H2AX in nonfixed mononuclear blood cells as well as in cultured cells, which is more sensitive and involves less steps compared with protocols involving fixed cells. This method can be used to monitor induction of gamma-H2AX in mononuclear cells from cancer patients undergoing radiotherapy and for detection of gamma-H2AX throughout the cell cycle in cultured cells. The method is based on the fact that H2AX like other histone proteins are retained in the nucleus when cells are lysed at physiological salt concentrations. Cells are therefore added without fixation to a solution containing detergent to lyse the cells along with a fluorescein isothiocyanate-labeled monoclonal gamma-H2AX antibody, DNA staining dye and blocking agents. The stained nuclei can be analyzed by flow cytometry to monitor the level of gamma-H2AX to determine the level of DSBs and DNA content and to determine the cell cycle stage. The omission of fixation simplifies staining and enhances the sensitivity. This protocol can be completed within 4-6 h.

Several publications in the scientific literature have raised concern about the individual and public health impact of adverse non-ionizing radiation (a-NIR) from electromagnetic field (EMF) exposure emanating from certain power,... more

Several publications in the scientific literature have raised concern about the individual and public health impact of adverse non-ionizing radiation (a-NIR) from electromagnetic field (EMF) exposure emanating from certain power, electrical and wireless devices commonly found in the home, workplace, school and community. Despite the many challenges in establishing irrefutable scientific proof of harm and the various gaps in elucidating the precise mechanisms of harm, epidemiological analyses continue to suggest considerable potential for injury and affliction as a result of a-NIR exposure. As environmental health has not been emphasized in medical education, some clinicians are not fully aware of possible EMF-related health problems and, as a result, manifestations of a-NIR may remain misdiagnosed and ineffectually managed. It is important for physicians and public health officials to be aware of the fundamental science and clinical implications of EMF exposure. A review of the scie...

The need to understand and accurately assess the health risks of low dose ionizing radiation is more important now than ever before. The global applications of ionizing radiation in medicine, mining, manufacturing, and the nuclear... more

The need to understand and accurately assess the health risks of low dose ionizing radiation is more important now than ever before. The global applications of ionizing radiation in medicine, mining, manufacturing, and the nuclear industry have increased exponentially in recent years. Parallel to this increase are the health concerns regarding occupational and medical exposures to radiation. The research presented here investigates the biological and health effects of ionizing radiation, specifically from medical diagnostic exposures. Medical diagnostic procedures such as x-rays and computed tomography (CT) scans account for a notable portion of the public's exposure to ionizing radiation. The health risk to humans associated with these low dose exposures is unknown. Often times they are correlated with risk estimates derived from much higher radiation doses. There is no doubt that very high dose ionizing radiation can be harmful; however, the same notion does not exist regardi...

Purpose: Cancer treatment is one of the most challenging diseases in the present era. Among a few modalities for cancer therapy, radiotherapy plays a pivotal role in more than half of all treatments alone or combined with other cancer... more

Purpose: Cancer treatment is one of the most challenging diseases in the present era. Among a few modalities for cancer therapy, radiotherapy plays a pivotal role in more than half of all treatments alone or combined with other cancer treatment modalities. Management of normal tissue toxicity induced by radiation is one of the most important limiting factors for an appropriate radiation treatment course. The evaluation of mechanisms of normal tissue toxicity has shown that immune responses especially inflammatory responses play a key role in both early and late side effects of exposure to ionizing radiation (IR). DNA damage and cell death, as well as damage to some organelles such as mitochondria initiate several signaling pathways that result in the response of immune cells. Massive cell damage which is a common phenomenon following exposure to a high dose of IR cause secretion of a lot of inflammatory mediators including cytokines and chemokines. These mediators initiate different changes in normal tissues that may continue for a long time after irradiation. In this study, we reviewed the mechanisms of inflammatory responses to IR that are involved in normal tissue toxicity and considered as the most important limiting factors in radiotherapy. Also, we introduced some agents that have been proposed for management of these responses. Conclusion: The early inflammation during the radiation treatment is often a limiting factor in radiotherapy. In addition to the limiting factors, chronic inflammatory responses may increase the risk of second primary cancers through continuous free radical production, attenuation of tumor suppressor genes and activation of oncogenes. Moreover, these effects may influence non-irradiated tissues through a mechanism named bystander effect.

Clonogenic assay or colony formation assay is an in vitro cell survival assay based on the ability of a single cell to grow into a colony. The colony is defined to consist of at least 50 cells. The assay essentially tests every cell in... more

Clonogenic assay or colony formation assay is an in vitro cell survival assay based on the ability of a single cell to grow into a colony. The colony is defined to consist of at least 50 cells. The assay essentially tests every cell in the population for its ability to undergo "unlimited" division. Clonogenic assay is the method of choice to determine cell reproductive death after treatment with ionizing radiation, but can also be used to determine the effectiveness of other cytotoxic agents. Only a fraction of seeded cells retains the capacity to produce colonies. Before or after treatment, cells are seeded out in appropriate dilutions to form colonies in 1-3 weeks. Colonies are fixed with glutaraldehyde (6.0% v/v), stained with crystal violet (0.5% w/v) and counted using a stereomicroscope. A method for the analysis of radiation dose-survival curves is included.

■ Abstract Cells are constantly under threat from,the cytotoxic and,mutagenic effects of DNA damaging,agents. These agents can either be exogenous,or formed within cells. Environmental,DNA-damaging,agents include UV light and ionizing... more

■ Abstract Cells are constantly under threat from,the cytotoxic and,mutagenic effects of DNA damaging,agents. These agents can either be exogenous,or formed within cells. Environmental,DNA-damaging,agents include UV light and ionizing radiation, as well as a variety of chemicals encountered in foodstuffs, or as air- and water-borne agents. Endogenous,damaging,agents include methylating,species and the reactive oxygen,species that arise during respiration. Although diverse responses