• Gamma Rays
  • The goal of this research is to establish a more mechanistic approach to estimating risk and to answer questions, including whether HZE effects can be scaled from those of gamma rays, whether risk is linear with low dose-rate, and how individual radiation sensitivity impacts the risks for astronauts, a population that is selected for many factors related to excellence in health. (wikipedia.org)
  • organisms
  • Studying dose response, and developing dose-response models, is central to determining "safe", "hazardous" and (where relevant) beneficial levels and dosages for drugs, pollutants, foods, and other substances to which humans or other organisms are exposed. (wikipedia.org)
  • The median infective dose (ID50) is the number of organisms received by a person or test animal qualified by the route of administration (e.g., 1,200 org/man per oral). (wikipedia.org)
  • Because of the difficulties in counting actual organisms in a dose, infective doses may be expressed in terms of biological assay, such as the number of LD50's to some test animal. (wikipedia.org)
  • In toxicology it is specifically the highest tested dose or concentration of a substance (i.e. a drug or chemical) or agent (e.g. radiation), at which no such adverse effect is found in exposed test organisms where higher doses or concentrations resulted in an adverse effect. (wikipedia.org)
  • Humans
  • While LD100 is estimated around 1000 rads for humans, and 56,128 rads (64,000 roentgens) for the fruit fly Drosophila melanogaster, a study showed that H. hebetor survived X-ray radiations of 158,080 rads (180,250 R). In this study, irradiated groups even had an increased life span compared to non-irradiated control groups, an effect attributed to the lack of activity of irradiated individuals. (wikipedia.org)
  • While the effects of high and acute doses of ionising radiation are easily observed and understood in humans (e.g. (wikipedia.org)
  • However, they cautioned that it is not yet known if radiation hormesis occurs outside the laboratory, or in humans. (wikipedia.org)
  • Reports by the United States National Research Council and the National Council on Radiation Protection and Measurements and the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) argue that there is no evidence for hormesis in humans and in the case of the National Research Council hormesis is outright rejected as a possibility. (wikipedia.org)
  • 1000
  • 1000 times background (average 47.7 mSv, maximum 2360 mSv excess cumulative dose) - it was not until 1992 that the radioactive contamination was discovered. (wikipedia.org)
  • dosage
  • The former means dosage or amount of dose administered to a person, whereas the latter means the time-dependent concentration (often in the circulatory blood or plasma) or concentration-derived parameters such as AUC (area under the concentration curve) and Cmax (peak level of the concentration curve) of the drug after its administration. (wikipedia.org)
  • In biological warfare infective dosage is the number of infective doses per minute for a cubic meter (e.g. (wikipedia.org)
  • toxins
  • Environmental factors, including toxins, radiation, and ultraviolet light, have cumulative effects, which are worsened by the loss of protective and restorative mechanisms due to alterations in gene expression and chemical processes within the eye. (wikipedia.org)
  • Within the hormetic zone there is generally a favorable biological responses to low exposures to toxins and other stressors. (wikipedia.org)
  • It is conjectured that low doses of toxins or other stressors might activate the repair mechanisms of the body. (wikipedia.org)
  • National Researc
  • This report was issued by the Committee on the Biological Effects of Ionizing Radiations, Division of Medical Sciences, National Research Council, National Academy of Sciences. (ratical.org)
  • tissue
  • Even with loco-regional disease, the prognosis of lung cancer remains poor because of inadequate control at the primary site after radiation therapy as the tolerance of the normal lung tissue, limits the dose that can be delivered [ 3 ]. (omicsonline.org)
  • the consequences of the difference on the dose-effect relations for normal tissue injury were studied by comparing different NTCP model/parameters extracted from a review of published studies. (nih.gov)
  • The material absorbing the radiation can be human tissue or silicon microchips or any other medium (for example, air, water, lead shielding, etc. (wikipedia.org)
  • The Röntgen equivalent physical (rep), introduced by Herbert Parker in 1945, was the absorbed energetic dose to tissue before factoring in relative biological effectiveness. (wikipedia.org)
  • cancer
  • Cancer induction after radiation therapy is known as a severe side effect. (springer.com)
  • The risk for breast cancer is according to this model for small doses consistent with the finding of the A-bomb survivors, has a maximum at doses of around 20 Gy and drops off only slightly at larger doses. (springer.com)
  • The model was used to predict the impact of the reduction of radiation volume on breast cancer risk. (springer.com)
  • The dose-response relationship obtained in this report can be used for the prediction of radiation induced secondary breast cancer of radiotherapy patients. (springer.com)
  • For this purpose it is not sufficient to apply the results from epidemiological studies on cancer induction from more than 20 years ago to the patient treated today, since radiation therapy changed significantly in the last decades, for instance radiation type, treatment technique, application of treatment, treatment duration and 3D dose distributions. (springer.com)
  • However, most of the epidemiological studies, which are published in large numbers, don't provide a correlation of cancer induction with dose. (springer.com)
  • Unfortunately, if a dose correlation is deduced, cancer induction is usually related to the integral dose or average organ dose and thus implies a linear dose-response relationship. (springer.com)
  • Radiotherapy of patients with Hodgkin's disease is very successful, but women treated with mantle field radiation experience up to a 30-fold increased risks for breast cancer compared with their peers in the general population. (springer.com)
  • They reconstructed the point doses where the secondary breast cancer was located and performed a case/control study to stratify breast cancer risk as a function of dose. (springer.com)
  • Population Heterogeneity Hypothesis on Radiation Induced Cancer," HEALTH PHYSICS 25: 97-104. (ratical.org)
  • We analyzed mitochondria DNA and genomic DNA extracted from Chernobyl childhood thyroid cancer tissues to find radiation signatures left in the DNA. (nii.ac.jp)
  • Through this study, we found new findings of radiation associated thyroid cancer and promoted international exchanges regarding scientific research and educations. (nii.ac.jp)
  • Journal Article] Inhibition of ABL tyrosine kinase potentiates radiation-induced terminal growth arrest in anaplastic thyroid cancer cells. (nii.ac.jp)
  • Cardiac dose from tangential breast cancer radiotherapy in the year 2006. (springer.com)
  • Distribution of coronary artery stenosis after radiation for breast cancer. (springer.com)
  • Coronary artery findings after left-sided compared with right-sided radiation treatment for early-stage breast cancer. (springer.com)
  • The sequence of experiments is designed to first explore the influence of iron load on the response and demonstrate that HFE knockout mice are more sensitive than the wild type to radiation-induced cancer in one or more of three target tissues (liver, colon and breast). (unt.edu)
  • Radiation increases the risk of cancer and other stochastic effects at any dose. (wikipedia.org)
  • A necessary step for improving space radiation cancer risk assessment is to perform studies on the molecular pathways that can cause cancer initiation and progression, and to extend these studies to learn how such pathways can be disrupted by HZE ions, including both genetic and epigenetic modifications that are noted as the hallmarks of cancer (Figure 4-8). (wikipedia.org)
  • This is because the baseline cancer rate is already very high and the risk of developing cancer fluctuates 40% because of individual life style and environmental effects, obscuring the subtle effects of low-level radiation. (wikipedia.org)
  • lethal
  • The linear quadratic model is now most often used to describe the cell survival curve, assuming that there are two mechanisms to cell death by radiation: A single lethal event or an accumulation of harmful but non-lethal events. (wikipedia.org)
  • Whereas single lethal events lead to an exponent that is linearly related to dose, the survival fraction function for a two-stage mechanism carries an exponent proportional to the square of dose. (wikipedia.org)
  • Because resistance varies from one individual to another, the "lethal dose" represents a dose (usually recorded as dose per kilogram of subject body weight) at which a given percentage of subjects will die. (wikipedia.org)
  • The lethal concentration is a lethal dose measurement used for gases or particulates. (wikipedia.org)
  • The median lethal dose, LD50 (abbreviation for "lethal dose, 50%"), LC50 (lethal concentration, 50%) or LCt50 (lethal concentration and time) of a toxin, radiation, or pathogen is the dose required to kill half the members of a tested population after a specified test duration. (wikipedia.org)
  • LD50 i.v." The related quantities LD50/30 or LD50/60 are used to refer to a dose that without treatment will be lethal to 50% of the population within (respectively) 30 or 60 days. (wikipedia.org)
  • The lowest lethal dose (LDLo) is the least amount of drug that can produce death in a given animal species under controlled conditions. (wikipedia.org)
  • exposures
  • The measured dose (usually in milligrams, micrograms, or grams per kilogram of body-weight for oral exposures or milligrams per cubic meter of ambient air for inhalation exposures) is generally plotted on the X axis and the response is plotted on the Y axis. (wikipedia.org)
  • There is also indication that exposures around this dose level will cause negative subclinical health impacts to neural development. (wikipedia.org)
  • DSBs
  • Unlike for enzymatically induced site-specific DSBs, little is known about processing of random "dirty-ended" DSBs created by DNA damaging agents such as ionizing radiation. (nih.gov)
  • Resection at the radiation-induced DSBs continues so that by the time of significant repair of DSBs at 1 hr there is about 1-2 kb resection per DSB end. (nih.gov)
  • Indications are that: for high-LET radiation, where complex DSBs occur with high frequency, little repair occurs, leading to cell death or the mis-rejoining of unrepairable ends with other radiation-induced DSB leads to large DNA deletions and chromosome aberrations. (wikipedia.org)
  • 1953
  • It was originally defined in CGS units in 1953 as the dose causing 100 ergs of energy to be absorbed by one gram of matter. (wikipedia.org)
  • In 1953 the ICRU recommended the rad, equal to 100 erg/g as a new unit of absorbed radiation, but then promoted a switch to the gray in the 1970s. (wikipedia.org)
  • Curves
  • Statistical analysis of dose-response curves may be performed by regression methods such as the probit model or logit model, or other methods such as the Spearman-Karber method. (wikipedia.org)
  • Dose-response curves are generally sigmoidal and monophasic and can be fit to a classical Hill equation. (wikipedia.org)
  • lung
  • However, children are particularly sensitive to radioactivity, with childhood leukemias and other cancers increasing even within natural and man-made background radiation levels (under 4 mSv cumulative with 1 mSv being an average annual dose from terrestrial and cosmic radiation excluding radon which primarily doses the lung). (wikipedia.org)
  • Hodgkin's
  • Coronary artery disease after radiation therapy for Hodgkin's lymphoma: coronary CT angiography findings and calcium scores in nine asymptomatic patients. (springer.com)
  • effects
  • What Knowledge Is Considered Certain Regarding Human Somatic Effects of Ionizing Radiation? (ratical.org)
  • Report prepared by the Advisory Committee on the Biological Effects of Ionizing Radiation. (ratical.org)
  • For most beneficial or recreational drugs, the desired effects are found at doses slightly greater than the threshold dose. (wikipedia.org)
  • It either does not provide the effects of drug with respect to duration and dose, or it does not address the interpretation of risk based on toxicologically relevant effects. (wikipedia.org)
  • Relation between benchmark dose and no-observed-adverse-effect level in clinical research: Effects of daily alcohol intake on blood pressure in Japanese salesmen" (Submitted manuscript). (wikipedia.org)
  • Japanese Atomic Bomb survivors), the effects of low-level radiation are very difficult to observe and highly controversial. (wikipedia.org)
  • Quoting results from a literature database research, the Académie des Sciences - Académie nationale de Médecine (French Academy of Sciences - National Academy of Medicine) stated in their 2005 report concerning the effects of low-level radiation that many laboratory studies have observed radiation hormesis. (wikipedia.org)
  • risks
  • Estimating risks of radiotherapy complications as part of informed consent: the high degree of variability between radiation oncologists may be related to experience. (biomedsearch.com)
  • METHODS AND MATERIALS: A survey was mailed to Australian radiation oncologists, who were asked to estimate risks of RT complications given 49 clinical scenarios. (biomedsearch.com)
  • Aggressive modification of traditional cardiovascular risk factors such as hypertension, dyslipidemia, and cigarette smoking is essential in patients at risk for RIHD, as these have been shown to potentiate the risks of radiation. (springer.com)
  • The International Commission on Radiological Protection maintains a model of these risks as a function of absorbed dose and other factors. (wikipedia.org)
  • hormesis
  • A pollutant or toxin showing hormesis thus has the opposite effect in small doses as in large doses. (wikipedia.org)
  • The hormesis model of dose response is vigorously debated. (wikipedia.org)
  • Radiation hormesis is the hypothesis that low doses of ionizing radiation (within the region of and just above natural background levels) are beneficial, stimulating the activation of repair mechanisms that protect against disease, that are not activated in absence of ionizing radiation. (wikipedia.org)
  • Government and regulatory bodies disagree on the existence of radiation hormesis and research points to the "severe problems and limitations" with the use of hormesis in general as the "principal dose-response default assumption in a risk assessment process charged with ensuring public health protection. (wikipedia.org)
  • Radiosurgery
  • Andisheh B, Bitaraf MA, Mavroidis P, Brahme A, Lind BK (2010) Vascular structure and binomial statistics for response modeling in radiosurgery of cerebral arteriovenous malformations. (springer.com)
  • biology
  • The light ions have a unique role in the development of modern radiation therapy where biological optimized radiation quality and intensity-modulated radiation therapy are increasingly coming into clinical interest, not least through a systems biology approach to therapy optimization. (springer.com)
  • tumor
  • The traditional dose distributional qualities of light ions like penumbra and depth dose are ideally suited for high-quality radiation therapy, and their radiation biological properties are even more important for eradicating large complex generally radiation resistant and/or hypoxic tumor volumes with minimal damage to surrounding normal tissues. (springer.com)
  • biological
  • Brahme A (2011) Accurate description of the cell survival and biological effect at low and high dose and LET's. (springer.com)
  • commonly
  • A commonly used dose-response curve is the EC50 curve, the half maximal effective concentration, where the EC50 point is defined as the inflection point of the curve. (wikipedia.org)
  • These measures are used more commonly with radiation, as survival beyond 60 days usually results in recovery. (wikipedia.org)
  • small
  • Prolongation of life of Tribolium confusum apparently due to small doses of X-rays. (wikipedia.org)
  • German pharmacologist Hugo Schulz first described such a phenomenon in 1888 following his own observations that the growth of yeast could be stimulated by small doses of poisons. (wikipedia.org)
  • Conclusions
  • 16 Conclusions In the two experimental models of hepatic damage and repair tested, a transient pattern of MMP10 expression was observed, which onset overlapped with the early inflammatory response The EGFR ligands AR, HB-EGF and Ereg were markedly up-regulated in mouse liver upon BDL. (docplayer.net)
  • Biologically
  • Brahme A (2003) Biologically optimized 3-dimensional in vivo predictive assay based radiation therapy using positron emission tomography-computerized tomography imaging. (springer.com)
  • Biologically based models using dose are preferred over the use of log(dose) because the latter can visually imply a threshold dose when in fact there is none. (wikipedia.org)
  • survival
  • Cell survival fractions are exponential functions with a dose-dependent term in the exponent due to the Poisson statistics underlying the stochastic process. (wikipedia.org)
  • typically
  • A dose of under 100 rad will typically produce no immediate symptoms other than blood changes. (wikipedia.org)
  • In some cases, it is the logarithm of the dose that is plotted on the X axis, and in such cases the curve is typically sigmoidal, with the steepest portion in the middle. (wikipedia.org)
  • high
  • Biophysical models have shown that the energy deposition events by high-LET radiation produce differential DNA lesions, including complex DNA breaks, and that there are qualitative differences between high- and low-LET radiation, in both the induction and the repair of DNA damage. (wikipedia.org)