The sievert (symbol: Sv) is the SI derived unit of ionizing radiation dose
Sievert may also refer to:
- Sievert (name), German given name and surname
The sievert (symbol: Sv) is the SI derived unit of ionizing radiation dose
Sievert may also refer to:
Dose or Dosage may refer to:
A Geiger counter is an electronic instrument used for detecting and measuring ionizing radiation. It is widely used in applications such as radiation dosimetry, radiological protection, experimental physics and the nuclear industry.
A radiation dosimeter is a device that measures dose uptake of external ionizing radiation. It is worn by the person being monitored when used as a personal dosimeter, and is a record of the radiation dose received. Modern electronic personal dosimeters can give a continuous readout of cumulative dose and current dose rate, and can warn the wearer with an audible alarm when a specified dose rate or a cumulative dose is exceeded. Other dosimeters, such as thermoluminescent or film types, require processing after use to reveal the cumulative dose received, and cannot give a current indication of dose while being worn.
The sievert is a unit in the International System of Units (SI) intended to represent the stochastic health risk of ionizing radiation, which is defined as the probability of causing radiation-induced cancer and genetic damage. The sievert is important in dosimetry and radiation protection. It is named after Rolf Maximilian Sievert, a Swedish medical physicist renowned for work on radiation dose measurement and research into the biological effects of radiation.
Ionizing radiation, including nuclear radiation, consists of subatomic particles or electromagnetic waves that have sufficient energy to ionize atoms or molecules by detaching electrons from them. Some particles can travel up to 99% of the speed of light, and the electromagnetic waves are on the high-energy portion of the electromagnetic spectrum.
The gray is the unit of ionizing radiation dose in the International System of Units (SI), defined as the absorption of one joule of radiation energy per kilogram of matter.
Radiation dosimetry in the fields of health physics and radiation protection is the measurement, calculation and assessment of the ionizing radiation dose absorbed by an object, usually the human body. This applies both internally, due to ingested or inhaled radioactive substances, or externally due to irradiation by sources of radiation.
Equivalent dose is a dose quantity H representing the stochastic health effects of low levels of ionizing radiation on the human body which represents the probability of radiation-induced cancer and genetic damage. It is derived from the physical quantity absorbed dose, but also takes into account the biological effectiveness of the radiation, which is dependent on the radiation type and energy. In the SI system of units, the unit of measure is the sievert (Sv).
The roentgen equivalent man (rem) is a CGS unit of equivalent dose, effective dose, and committed dose, which are dose measures used to estimate potential health effects of low levels of ionizing radiation on the human body.
Absorbed dose is a dose quantity which is the measure of the energy deposited in matter by ionizing radiation per unit mass. Absorbed dose is used in the calculation of dose uptake in living tissue in both radiation protection, and radiology. It is also used to directly compare the effect of radiation on inanimate matter such as in radiation hardening.
In radiation physics, kerma is an acronym for "kinetic energy released per unit mass", defined as the sum of the initial kinetic energies of all the charged particles liberated by uncharged ionizing radiation in a sample of matter, divided by the mass of the sample. It is defined by the quotient .
Rolf Maximilian Sievert was a Swedish medical physicist whose major contribution was in the study of the biological effects of ionizing radiation.
The ionization chamber is the simplest type of gaseous ionisation detector, and is widely used for the detection and measurement of many types of ionizing radiation, including X-rays, gamma rays, alpha particles and beta particles. Conventionally, the term "ionization chamber" refers exclusively to those detectors which collect all the charges created by direct ionization within the gas through the application of an electric field. It uses the discrete charges created by each interaction between the incident radiation and the gas to produce an output in the form of a small direct current. This means individual ionising events cannot be measured, so the energy of different types of radiation cannot be differentiated, but it gives a very good measurement of overall ionising effect.
Radiobiology is a field of clinical and basic medical sciences that involves the study of the effects of ionizing radiation on living things, in particular health effects of radiation. Ionizing radiation is generally harmful and potentially lethal to living things but can have health benefits in radiation therapy for the treatment of cancer and thyrotoxicosis. Its most common impact is the induction of cancer with a latent period of years or decades after exposure. High doses can cause visually dramatic radiation burns, and/or rapid fatality through acute radiation syndrome. Controlled doses are used for medical imaging and radiotherapy.
The collective effective dose, dose quantity S, is calculated as the sum of all individual effective doses over the time period or during the operation being considered due to ionizing radiation. It can be used to estimate the total health effects of a process or accidental release involving ionizing radiation to an exposed population. The total collective dose is the dose to the exposed human population between the time of release until its elimination from the environment, perhaps integrating to time equals infinity. However, doses are generally reported for specific populations and a stated time interval. The International Commission on Radiological Protection (ICRP) states: "To avoid aggregation of low individual doses over extended time periods and wide geographical regions the range in effective dose and the time period should be limited and specified.
The roentgen or röntgen is a legacy unit of measurement for the exposure of X-rays and gamma rays, and is defined as the electric charge freed by such radiation in a specified volume of air divided by the mass of that air . In 1928, it was adopted as the first international measurement quantity for ionizing radiation to be defined for radiation protection, as it was then the most easily replicated method of measuring air ionization by using ion chambers. It is named after the German physicist Wilhelm Röntgen, who discovered X-rays and was awarded the first Nobel Prize in Physics for the discovery.
Recognized effects of higher acute radiation doses are described in more detail in the article on radiation poisoning. Although the International System of Units (SI) defines the sievert (Sv) as the unit of radiation dose equivalent, chronic radiation levels and standards are still often given in units of millirems (mrem), where 1 mrem equals 1/1,000 of a rem and 1 rem equals 0.01 Sv. Light radiation sickness begins at about 50–100 rad.
A Sievert chamber is a type of ionization chamber used in radiation dose measurements. It was invented by Professor Rolf Maximilian Sievert in Sweden in the years 1920-40.
Exposure to ionizing radiation is known to increase the future incidence of cancer, particularly leukemia. The mechanism by which this occurs is well understood, but quantitative models predicting the level of risk remain controversial. The most widely accepted model posits that the incidence of cancers due to ionizing radiation increases linearly with effective radiation dose at a rate of 5.5% per sievert; if correct, natural background radiation is the most hazardous source of radiation to general public health, followed by medical imaging as a close second. Additionally, the vast majority of non-invasive cancers are non-melanoma skin cancers caused by ultraviolet radiation. Non-ionizing radio frequency radiation from mobile phones, electric power transmission, and other similar sources have been investigated as a possible carcinogen by the WHO's International Agency for Research on Cancer, but to date, no evidence of this has been observed.
The International Radiation Protection Association (IRPA) is an independent non-profit association of national and regional radiation protection societies, and its mission is to advance radiation protection throughout the world. It is the international professional association for radiation protection.