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Deep-dose Equivalent
The Deep-dose equivalent (DDE) is a measure of external radiation exposure defined by US regulations. It is reported alongside eye and shallow dose equivalents on typical US dosimetry reports. It represents the dose equivalent at a tissue depth of 1 cm (1000 mg/cm2) due to external whole-body exposure to ionizing radiation. Dose due to external radiation tends to decrease with depth because of the shielding effects of outer tissues. The reference depth of 1 cm essentially discounts alpha and beta radiation that are easily shielded by the skin, clothing, and bone surface, while taking minimal credit for any self-shielding from the more penetrating gamma rays. This makes the deep-dose equivalent a conservative measure of internal organ exposure to external radiation, while eye and skin exposure to external radiation must be accounted differently. Deep-dose equivalent does include any contribution from internal contamination. See also * Radioactivity * Radiation poiso ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dose Equivalent
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). Application To enable consideration of stochastic health risk, calculations are performed to convert the physical quantity absorbed dose into equivalent dose, the details of which depend on the radiation type. For applications in radiation protection and dosimetry assessment, the International Commission on Radiological Protection (ICRP) and the International Commission on Radiation Units and Measurements (ICRU) have published recommendations and data on how to calculate equivalent dose from absorbed dose. Equiv ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ionizing Radiation
Ionizing radiation (or ionising 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. Gamma rays, X-rays, and the higher energy ultraviolet part of the electromagnetic spectrum are ionizing radiation, whereas the lower energy ultraviolet, visible light, nearly all types of laser light, infrared, microwaves, and radio waves are non-ionizing radiation. The boundary between ionizing and non-ionizing radiation in the ultraviolet area is not sharply defined, as different molecules and atoms ionize at different energies. The energy of ionizing radiation starts between 10 electronvolts (eV) and 33 eV. Typical ionizing subatomic particles include alpha particles, beta particles, and neutrons. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ionizing Radiation
Ionizing radiation (or ionising 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. Gamma rays, X-rays, and the higher energy ultraviolet part of the electromagnetic spectrum are ionizing radiation, whereas the lower energy ultraviolet, visible light, nearly all types of laser light, infrared, microwaves, and radio waves are non-ionizing radiation. The boundary between ionizing and non-ionizing radiation in the ultraviolet area is not sharply defined, as different molecules and atoms ionize at different energies. The energy of ionizing radiation starts between 10 electronvolts (eV) and 33 eV. Typical ionizing subatomic particles include alpha particles, beta particles, and neutrons. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dosimetry
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. Internal dosimetry assessment relies on a variety of monitoring, bio-assay or radiation imaging techniques, whilst external dosimetry is based on measurements with a dosimeter, or inferred from measurements made by other radiological protection instruments. Dosimetry is used extensively for radiation protection and is routinely applied to monitor occupational radiation workers, where irradiation is expected, or where radiation is unexpected, such as in the aftermath of the Three Mile Island, Chernobyl or Fukushima radiological release incidents. The public dose take-up is measured and calculated from a variety of indicators such as ambient mea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Absorbed Dose
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 (reduction of harmful effects), and radiology (potential beneficial effects for example in cancer treatment). It is also used to directly compare the effect of radiation on inanimate matter such as in radiation hardening. The SI unit of measure is the gray (Gy), which is defined as one Joule of energy absorbed per kilogram of matter. The older, non-SI CGS unit rad, is sometimes also used, predominantly in the USA. Deterministic effects Conventionally, in radiation protection, unmodified absorbed dose is only used for indicating the immediate health effects due to high levels of acute dose. These are tissue effects, such as in acute radiation syndrome, which are also known as deterministic effects. These are effects which are certain to happen in a s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Total Effective Dose Equivalent
The Total effective dose equivalent (TEDE) is a radiation dosimetry quantity defined by the US Nuclear Regulatory Commission to monitor and control human exposure to ionizing radiation. It is defined differently in the NRC regulations and NRC glossary. According to the regulations, it is the sum of effective dose equivalent from external exposure and committed effective dose equivalent from internal exposure, thereby taking into account all known exposures. However, the NRC glossary defines it as the sum of the deep-dose equivalent and committed effective dose equivalent, which would appear to exclude the effective dose to the skin and eyes from non-penetrating radiation such as beta. These surface doses are included in the NRC's shallow dose equivalent, along with contributions from penetrating (gamma) radiation. Regulatory limits are imposed on the TEDE for occupationally exposed individuals and members of the general public. See also * Radioactivity * Radiation poisoning * I ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Collective Dose
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. Limitations The ICRP states; "Collective effective dose is an instrument for optimisation, for comparing radiological technolo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cumulative Dose
Cumulative dose is the total dose resulting from repeated exposures of ionizing radiation to an occupationally exposed worker to the same portion of the body, or to the whole body, over a period of time. In medicine, the total amount of a drug or radiation given to a patient over time; for example, the total dose of radiation given in a series of radiation treatments or imaging exams. Recent studies have drawn attention to high cumulative doses (>100 mSv) to millions of patients undergoing recurrent CT scans during a 1- to 5-year period. This has resulted in a debate on whether CT is really a low-dose imaging modality. See also * Radioactivity * Radiation poisoning * Collective dose *Committed dose equivalent *Committed effective dose equivalent Committed dose equivalent and Committed effective dose equivalent are dose quantities used in the United States system of radiological protection for irradiation due to an internal source. Committed dose equivalent (CDE) CDE is defined ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Committed Dose Equivalent
Committed dose equivalent and Committed effective dose equivalent are dose quantities used in the United States system of radiological protection for irradiation due to an internal source. Committed dose equivalent (CDE) CDE is defined by the United States Nuclear Regulatory Commission in Title 10, Section 20.1003, of the Code of Federal Regulations (10 CFR 20.1003), such that "The Committed dose equivalent, CDE (HT,50) is the dose to some specific organ or tissue of reference (T) that will be received from an intake of radioactive material by an individual during the 50-year period following the intake". "The calculation of the committed effective dose equivalent (CEDE) begins with the determination of the equivalent dose, HT, to a tissue or organ, T. Where DT,R is the absorbed dose in rads (one gray, an SI unit, equals 100 rads) averaged over the tissue or organ, T, due to radiation type, R, and WR is the radiation weighting factor. The unit of equivalent dose is the rem (sievert ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Committed Effective Dose Equivalent
Committed dose equivalent and Committed effective dose equivalent are dose quantities used in the United States system of radiological protection for irradiation due to an internal source. Committed dose equivalent (CDE) CDE is defined by the United States Nuclear Regulatory Commission in Title 10, Section 20.1003, of the Code of Federal Regulations (10 CFR 20.1003), such that "The Committed dose equivalent, CDE (HT,50) is the dose to some specific organ or tissue of reference (T) that will be received from an intake of radioactive material by an individual during the 50-year period following the intake". "The calculation of the committed effective dose equivalent (CEDE) begins with the determination of the equivalent dose, HT, to a tissue or organ, T. Where DT,R is the absorbed dose in Rad (unit), rads (one gray, an SI unit, equals 100 rads) averaged over the tissue or organ, T, due to radiation type, R, and WR is the radiation weighting factor. The unit of equivalent dose is the R ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
