Topic
Sievert
About: Sievert is a research topic. Over the lifetime, 140 publications have been published within this topic receiving 3375 citations. The topic is also known as: Sv.
Papers published on a yearly basis
Papers
TL;DR: In this review, effective dose equivalent and effective dose, as established by the International Commission on Radiological Protection in 1977 and 1990, respectively, are defined and various methods of calculating these quantities are presented for radionuclides, radiography, fluoroscopy, computed tomography and mammography.
Abstract: The concept of "effective dose" was introduced in 1975 to provide a mechanism for assessing the radiation detriment from partial body irradiations in terms of data derived from whole body irradiations. The effective dose is the mean absorbed dose from a uniform whole-body irradiation that results in the same total radiation detriment as from the nonuniform, partial-body irradiation in question. The effective dose is calculated as the weighted average of the mean absorbed dose to the various body organs and tissues, where the weighting factor is the radiation detriment for a given organ (from a whole-body irradiation) as a fraction of the total radiation detriment. In this review, effective dose equivalent and effective dose, as established by the International Commission on Radiological Protection in 1977 and 1990, respectively, are defined and various methods of calculating these quantities are presented for radionuclides, radiography, fluoroscopy, computed tomography and mammography. In order to calculate either quantity, it is first necessary to estimate the radiation dose to individual organs. One common method of determining organ doses is through Monte Carlo simulations of photon interactions within a simplified mathematical model of the human body. Several groups have performed these calculations and published their results in the form of data tables of organ dose per unit activity or exposure. These data tables are specified according to particular examination parameters, such as radiopharmaceutical, x-ray projection, x-ray beam energy spectra or patient size. Sources of these organ dose conversion coefficients are presented and differences between them are examined. The estimates of effective dose equivalent or effective dose calculated using these data, although not intended to describe the dose to an individual, can be used as a relative measure of stochastic radiation detriment. The calculated values, in units of sievert (or rem), indicate the amount of whole-body irradiation that would yield the equivalent radiation detriment as the exam in question. In this manner, the detriment associated with partial or organ-specific irradiations, as are common in diagnostic radiology, can be assessed.
314 citations
TL;DR: Overall radiation exposures in children with heart disease are relatively low; however, select cohorts receive significant exposure, which highlights the need to limit radiation dose, particularly for high-exposure modalities.
Abstract: Background—Children with heart disease are frequently exposed to imaging examinations that use ionizing radiation. Although radiation exposure is potentially carcinogenic, there are limited data on cumulative exposure and the associated cancer risk. We evaluated the cumulative effective dose of radiation from all radiation examinations to estimate the lifetime attributable risk of cancer in children with heart disease. Methods and Results—Children ≤6 years of age who had previously undergone 1 of 7 primary surgical procedures for heart disease at a single institution between 2005 and 2010 were eligible for the study. Exposure to radiation-producing examinations was tabulated, and cumulative effective dose was calculated in millisieverts. These data were used to estimate lifetime attributable risk of cancer above baseline using the approach of the Committee on Biological Effects of Ionizing Radiation VII. The cohort included 337 children exposed to 13 932 radiation examinations. Conventional radiographs re...
216 citations
TL;DR: The Sievert (Sv) unit as mentioned in this paper is a unit that multiplies the absorbed dose in grays (Gy) by the relative effectiveness of the particle or ray to inflict damage.
Abstract: Ionizing radiation fills the universe. Daily ionizing particles and rays collide with molecules in ≈1% of the 100 trillion cells that make up the average human. These collisions generate clusters of free radicals known as reactive oxygen species that randomly damage cellular constituents including DNA (1). Certain types of ionizing radiation are more effective at generating reactive oxygen species; one α-particle is at least 10 times more damaging than one γ-ray. To take these differences into account, the Sievert (Sv), a unit that multiplies the absorbed dose in grays (Gy) by the relative effectiveness of the particle or ray to inflict damage, was developed. On this scale, natural background radiation is ≈0.01 mSv/day, although there are areas on earth that have values 5-fold higher (2), and space-station inhabitants may receive ≈1 mSv/day (3). At the other end of the scale, acute exposures of >150 mSv, a range known as high-dose radiation, have measurable and often serious immediate effects on humans (4). Between background and high-dose radiation is the range of exposures known as low-dose radiation. Low-dose radiation has no immediately noticeable effects on humans; nevertheless there is great interest in its long-term biological effects, which may include cancer in exposed individuals and genetic defects in their progeny.
178 citations
International Agency for Research on Cancer1, University of Ottawa2, Radiation and Nuclear Safety Authority3, New Generation University College4, American University of Beirut5, Columbia University6, Vilnius University7, Health Protection Agency8, Autonomous University of Madrid9, Institut de radioprotection et de sûreté nucléaire10, National Institute for Occupational Safety and Health11, Semmelweis University12
TL;DR: The most informative low-dose radiation study to date provides little evidence for a relationship between mortality from non-malignant diseases and radiation dose, but cannot rule out risks per unit dose of the same order of magnitude as found in studies at higher doses.
Abstract: Background: Ionizing radiation at very high (radio-therapeutic) dose levels can cause diseases other than cancer, particularly heart diseases. There is increasing evidence that doses of the order of a few sievert (Sv) may also increase the risk of non-cancer diseases. It is not known, however, whether such effects also occur following the lower doses and dose rates of public health concern. Methods: We used data from an international (15-country) nuclear workers cohort study to evaluate whether mortality from diseases other than cancer is related to low doses of external ionizing radiation. Analyses included 275 312 workers with adequate information on socioeconomic status, over 4 million person-years of follow-up and an average cumulative radiation dose of 20.7 mSv; 11 255 workers had died of non-cancer diseases. Results: The excess relative risk (ERR) per Sv was 0.24 [95% CI (confidence intervals) -0.23, 0.78] for mortality from all non-cancer diseases and 0.09 (95% CI -0.43, 0.70) for circulatory diseases. Higher risk estimates were observed for mortality from respiratory and digestive diseases, but confidence intervals included zero. Increased risks were observed among the younger workers (attained age <50 years, identified post hoc) for all groupings of non-cancer causes of death, including external causes. It is unclear therefore whether these findings reflect real effects of radiation, random variation or residual confounding. Conclusions: The most informative low-dose radiation study to date provides little evidence for a relationship between mortality from non-malignant diseases and radiation dose. However, we cannot rule out risks per unit dose of the same order of magnitude as found in studies at higher doses. © The Author 2007; all rights reserved.
163 citations
TL;DR: A practical system of dosage measurement is described, applicable to all forms of radium therapy other than certain types of interstitial implantation, and the international “r” unit is accepted as a satisfactory unit of quantity of gamma radiation.
Abstract: A practical system of dosage measurement is described, applicable to all forms of radium therapy other than certain types of interstitial implantation. The international “r” unit is accepted as a satisfactory unit of quantity of gamma radiation, and the Imc.Hr. of Sievert assessed as equal to 8·4 “r.” Graphs are submitted showing for various distances the amount of radium required on any applicator to produce a dose of 1,000 “r” over any desired area. A system of “Rules” is also given, defining how, in the situations met with in actual clinical practice, radium must be distributed upon such applicators to produce a reasonably homogeneous radiation over the whole of a treated surface. The effects of certain dosages of gamma radiation on normal and malignant tissue are described. The lethal dose for squamous epithelioma appears to be 6,000 “r” delivered as continuous radiation for a period of eight days; normal healthy skin safely tolerates the same dose delivered over a like period, and normal mucosa consi...
152 citations
Related Topics (5)
Performance Metrics
| Year | Papers |
|---|---|
| 2021 | 4 |
| 2019 | 2 |
| 2018 | 3 |
| 2016 | 10 |
| 2015 | 7 |
| 2014 | 8 |