Radiation Protection Glossary
A radiation protection glossary for Radiation Protection Supervisors (RPS), Radiation Protection Advisers (RPA) and anyone else interesting in radiation safety terms and definitions. The glossary is a mixture of health physics , phrases related to radiation protection legislation, transport, practical safety, technical terms and similar.
Search the Glossary by either clicking on a letter or typing a keyword into the search box. This glossary is relational so when looking at one term you can click through to other related terms as required.
For formal advice, see our Radiation Protection Adviser pages.
E
Effective dose
The Effective Dose is obtained by taking the Equivalent Dose (Dose Equivalent) and multiplying by a Tissue Weighting Factor which relates to the organs / tissues under consideration. Effective Dose can therefore also be considered a doubly weighted Absorbed Dose since it takes into account the type of radiation (radiation weighting factor) and the target organ / tissue. The quantity can be used to express Detriment to the whole body as a summation of several different doses of radiation with varying radiation weighting factors (radiation type) and targets.
The Effective Dose is obtained by taking the Equivalent Dose (Dose Equivalent) and multiplying by a Tissue Weighting Factor which relates to the organs / tissues under consideration. Effective Dose can therefore also be considered a doubly weighted Absorbed Dose since it takes into account the type of radiation (radiation weighting factor) and the target organ / tissue. The quantity can be used to express Detriment to the whole body as a summation of several different doses of radiation with varying radiation weighting factors (radiation type) and targets.
Electromagnetic spectrum
The electromagnetic spectrum covers a wide range of wavelengths and Photon energies. It ranges from Gamma Rays at one end (High Frequency, High Energy and Low Wave Length) to radio waves at the other (Low Frequency, Low Energy and Long Wave Length). For Ionising Radiation protection purposes we are concerned with X-Rays and Gamma Rays.
The electromagnetic spectrum covers a wide range of wavelengths and Photon energies. It ranges from Gamma Rays at one end (High Frequency, High Energy and Low Wave Length) to radio waves at the other (Low Frequency, Low Energy and Long Wave Length). For Ionising Radiation protection purposes we are concerned with X-Rays and Gamma Rays.
Electron
The electron is a low mass particle (1/1836 that of a Proton) with a unit negative electric charge. In simple terms the electrons are said to orbit around the Nucleus of Atoms. Positively charged electrons can also exist, these being known as Positrons. The electron is closely related (identical in fact) to the Beta Particle.
The electron is a low mass particle (1/1836 that of a Proton) with a unit negative electric charge. In simple terms the electrons are said to orbit around the Nucleus of Atoms. Positively charged electrons can also exist, these being known as Positrons. The electron is closely related (identical in fact) to the Beta Particle.
Electron volt
The electron volt (eV) is a unit used in Radiation Protection / Health Physics to describe the energy of Ionising Radiation. The value of the eV is derived from the energy required to accelerate an electron through a potential of 1 volt. In more familiar units the eV is approximately equivalent to 1.6 E-19 joules. In everyday use the units of KeV (or MeV) are used as the eV is obviously an extremely small quantity. In training we often say the eV represents the 'punch' that the ionising radiation has to do work (damage) and so can be related to hazard potential.
The electron volt (eV) is a unit used in Radiation Protection / Health Physics to describe the energy of Ionising Radiation. The value of the eV is derived from the energy required to accelerate an electron through a potential of 1 volt. In more familiar units the eV is approximately equivalent to 1.6 E-19 joules. In everyday use the units of KeV (or MeV) are used as the eV is obviously an extremely small quantity. In training we often say the eV represents the 'punch' that the ionising radiation has to do work (damage) and so can be related to hazard potential.
Element
An element represents the simplest form of a chemical where all the Atoms share the same Atomic Number. This will include, for example, Hydrogen, Oxygen and Carbon.
An element represents the simplest form of a chemical where all the Atoms share the same Atomic Number. This will include, for example, Hydrogen, Oxygen and Carbon.
Enriched uranium
Uranium where the content U-235 is increased above its natural value of around 0.7% by weight. The enrichment process will also yield Depleted Uranium. Enriched Uranium is Fissile and can undergo nuclear fission under certain conditions, it's therefore used in Nuclear Power production and Nuclear Weapons.
Uranium where the content U-235 is increased above its natural value of around 0.7% by weight. The enrichment process will also yield Depleted Uranium. Enriched Uranium is Fissile and can undergo nuclear fission under certain conditions, it's therefore used in Nuclear Power production and Nuclear Weapons.
Environmental Decontamination
With respect to Radiation Protection, environmental decontamination refers to the systematic clean-up of Radioactive Contamination within the workplace or wider environment. Also see Personal Decontamination.
With respect to Radiation Protection, environmental decontamination refers to the systematic clean-up of Radioactive Contamination within the workplace or wider environment. Also see Personal Decontamination.
Environmental Exposure
With respect to Radiation Protection, environmental exposure refers to Ionising Radiation exposure within the workplace or wider environment. Also see Personal Exposure.
With respect to Radiation Protection, environmental exposure refers to Ionising Radiation exposure within the workplace or wider environment. Also see Personal Exposure.
EPD
With respect to Radiation Protection, EPD stands for 'Electronic Personal Dosimeter'. A number of types of device can function as an EPD which is a type of Active Dosimeter. It is designed to provide real time information on Dose and Dose Rate.
With respect to Radiation Protection, EPD stands for 'Electronic Personal Dosimeter'. A number of types of device can function as an EPD which is a type of Active Dosimeter. It is designed to provide real time information on Dose and Dose Rate.
Equivalent Dose
Equivalent Dose (can be referred to as Dose Equivalent) is a quantity which takes into effect 'radiation quality', which relates to the degree to which a type of Ionising Radiation will produce biological damage. Equivalent Dose is obtained by multiplying the Absorbed Dose by a Radiation Weighting Factor or Quality Factor if Dose Equivalent is used . The resulting quantity can then be expressed numerically in Sieverts (Sv) or in the old units of Rem. The quantity is independent of the absorbing material (i.e. tissue).
Equivalent Dose (can be referred to as Dose Equivalent) is a quantity which takes into effect 'radiation quality', which relates to the degree to which a type of Ionising Radiation will produce biological damage. Equivalent Dose is obtained by multiplying the Absorbed Dose by a Radiation Weighting Factor or Quality Factor if Dose Equivalent is used . The resulting quantity can then be expressed numerically in Sieverts (Sv) or in the old units of Rem. The quantity is independent of the absorbing material (i.e. tissue).
Erythema
Erythema presents itself as a reddening of the skin which is caused by blood vessel dilation. It is a common sign of Deterministic Radiation Effects, particularly from high energy Beta emitters or X-Rays.
Erythema presents itself as a reddening of the skin which is caused by blood vessel dilation. It is a common sign of Deterministic Radiation Effects, particularly from high energy Beta emitters or X-Rays.
External Radiation
The external radiation (hazard) exists where an absorber (typically a person) is being exposed to a source of Ionising Radiation external to the body. Examples would include exposures to Sealed Sources, dental X-Rays and Cosmic Rays. One feature of this hazard is that moving the absorber away from the source (usually) results in a reduction in the Dose of ionising radiation to that absorber, which is not the case for Internal Radiation hazards.
The external radiation (hazard) exists where an absorber (typically a person) is being exposed to a source of Ionising Radiation external to the body. Examples would include exposures to Sealed Sources, dental X-Rays and Cosmic Rays. One feature of this hazard is that moving the absorber away from the source (usually) results in a reduction in the Dose of ionising radiation to that absorber, which is not the case for Internal Radiation hazards.
Radiation is one of the important factors in evolution. It causes mutation, and some level of mutation is actually good for evolution