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GLOSSARY – Nagasaki University Center for Frontier Sciences

GLOSSARY OF expressed by the linear absorption RADIATION TERMS coefficient.

ACCELERATOR (): A device

that accelerates charged sub-atomic ABSOLUTE RISK: The rate of disease to very great . These among a population. particles may be used for basic

research, radioisotope production or for , D: The fundamental direct medical of patients. dose quantity given by the mean imparted to of mass by ionizing ACTIVATION: Absorption, usually of radiation. The SI unit for absorbed dose is or charged particles (the minimum per kilogram (J kg-1) and its special energy to induce this effect is 10 MeV) by name is (Gy). 1 Gy = 1 J/kg = 100 nuclei thereby making them radioactive. rads.

ACTIVE () BONE MARROW: The ABSORBED DOSE, MEAN IN A TISSUE organ system bone marrow contains the OR ORGAN, DT: The absorbed dose DT, systems for the formation of blood cells averaged over the tissue or organ T, which starting from the pluripotent haematopietic is given by stem cells to the mature blood cells.

ACTIVITY, A: Is the number of nuclear where εT is the mean total energy imparted transformations occurring in a given in a tissue or organ T, and mT is the mass quantity of material per unit . The SI of that tissue or organ. unit for the transformation rate is the

Becquerel (Bq), which is defined as one ABSORPTION: Transfer or deposition of disintegration per second. 1 Bq = 2.7 x some or all of the energy of radiation 10-11Ci. 1 Ci = 3.7 x 1010Bq. traversing matter.

ACUTE RADIATION SYNDROME (ARS): ABSORPTION COEFFICIENT: Since the A serious illness caused by receiving a absorption of gamma or X-rays is dose greater than 75 rads of penetrating exponential in , these radiations radiation to the body in a short time (usually have no clear cut range. The fractional minutes). The earliest symptoms are decrease in the intensity of such a beam nausea, fatigue, vomiting, and diarrhea. per unit thickness of the absorber is 1 GLOSSARY – Nagasaki University Center for Frontier Life Sciences

Hair loss, bleeding, swelling of the mouth ANNUAL LIMIT ON INTAKE (ALI): The and throat, and general loss of energy may activity of a which, upon follow. If the exposure has been ingestion, results in an exposure equal to approximately 1,000 rads or more, death the annual maximum permissible dose. may occur within 2 – 4 weeks. APOPTOSIS: An active biochemical ADAPTIVE RESPONSE: A post-irradiation process of programmed cell death following cellular response which, typically, serves to radiation or other insults. increase the resistance of the cell to a subsequent . ATOM: A particle of matter indivisible by chemical means. It is the fundamental : A positively charged building block of elements. highly energetic nuclear fragment, comprised of two neutrons and two ATOMIC ENERGY BASIC LOW: The (helium nucleus). Japanese Law established in 1955, which declares the use of atomic energy only for AMBIENT DOSE EQUIVALENT, H*(10): peaceful aim through democratic The dose equivalent at a point in a administration, autonomous radiation that would be produced by accomplishment and results disclosure in the corresponding expanded and aligned the public. field in the ICRU sphere at a depth of 10 mm on the radius vector opposing the ATOMIC NUMBER: The number assigned direction of the aligned field. The unit of to each element on the basis of the number ambient dose equivalent is joule per of protons found in the element's nucleus. kilogram (J kg-1) and its special name is (Sv). ATOMIC WEIGHT (ATOMIC MASS): Approximately the sum of the number of ANION: A negatively charged . protons and neutrons found in the nucleus of an atom. ANNIHILATION RADIATION: interact with negative resulting in ATTENUATION: The reduction of the the disappearance of both particles and the intensity of a beam of gamma or x-rays as it release of two annihilation 511 keV passes through some material. Beam . energy can be lost by deposition (absorption) and/or by deflection (deflection

2 GLOSSARY – Nagasaki University Center for Frontier Life Sciences attenuation). The three primary defined as one nuclear disintegration per mechanisms by which energy is transferred second (dps). 1 Bq = 2.7 x 10-11Ci. 1 Ci = from the beam to the material through 3.7 x 1010Bq. which it passes are the , the Compton effect and pair production. : Negatively charged particle emitted from the nucleus of an ATTRIBUTABLE RISK: The estimated rate atom. It is just an energetic . of a disease (such as lung ) that could, in theory, prevented if all exposures BIAS: Factors that influence the outcome to a particular causative agent (such as of data collection, such as causing certain ) were eliminated. measurements to have a greater chance of being included than others. AVERTED DOSE: The dose prevented or avoided by the application of a protective : The minimum energy measure or set of protective measures, i.e., required to separate a nucleus into its the difference between the projected dose component neutrons and protons. if the protective measure(s) had not been applied and the expected residual dose. BIOASSAY: Any procedure used to determine the nature, activity, location, or : The retention of in the body by in radiation to which a member of the vivo measurement or by in vitro analysis of population is exposed from natural sources, material excreted or otherwise removed such as terrestrial radiation due to naturally from the body. occurring radionuclides in the soil, cosmic radiation originating in outer , and BOHR RADIUS: The size of a ground state naturally occurring radionuclides in the hydrogen atom as calculated by Niels Bohr human body. using a mix of classical physics and mechanics. BEAM: A flow of electromagnetic or particulate radiation that is generally : Radiation treatment unidirectional or is divergent from a of a patient using sealed or unsealed but is confined to a sources of radiation placed within the small angle. patient’s body.

BECQUEREL (Bq): The SI unit of activity BRANCHING: The occurrence of two or

3 GLOSSARY – Nagasaki University Center for Frontier Life Sciences more modes by which a radionuclide can undergo to the ultimate CASE-CONTROL STUDY: An stable state. An individual atom of a nuclide epidemiologic study in which people with exhibiting branching disintegrates by one disease and a similarly composed control mode only. The fraction disintegrating by a group are compared in terms of exposures particular mode is the branching fraction for to a putative causative agent. that mode. The branching ratio is the ratio of two specified branching fractions (also CHARACTERISTIC X-RAY: A collision of called multiple disintegration). the fast-moving electrons with the atom first causes a tightly bound inner-shell electron : Secondary to be ejected from the atom; a loosely electromagnetic radiations produced by the bound outer-shell electron then falls into rapid deceleration of charged particles in the inner shell to fill the vacancy. In the strong electromagnetic fields. The process, a single (characteristic likelihood of emission is proportional to the X-ray) is emitted by the atom with an mass of the nucleus of the absorber. energy equal to the difference between the inner-shell and outer-shell vacancy states. BYSTANDER EFFECT: A response in unirradiated cells that is triggered by COHORT STUDY: An epidemiologic study signals received from irradiated in which groups of people (the cohort) are neighbouring cells. identified with respect to the presence or absence of exposure to a disease-causing CARRIER: A quantity of non-radioactive or agent, and in which the outcomes of non-labeled material of the same chemical disease rates are compared; also called a composition as its corresponding follow-up study. radioactive or labeled counterpart. : The estimated dose CARRIER-FREE: A preparation of for an area or region multiplied by the radioisotope to which no carrier has been estimated population in that area or region. added and for which precautions have been taken to minimize contamination with EQUIVALENT: The other isotopes. Material of high specific total dose equivalent averaged throughout activity is often loosely referred to as a tissue 50 years after body uptake of the "carrier-free" but is more correctly defined radionuclide. as "high isotopic abundance".

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COMPTON EFFECT: Interactive effect of excess energy of unstable nucleus to one X-ray and gamma radiation with matter. of its own orbiting electrons. The Compton effect is the elastic scattering of a quantum with a free or quasi-free COSMIC RADIATION: Radiation produced electron from the electron sheath of an in when heavy particles from atom. Part of the energy and the pulse of other galaxies (nuclei of all known natural the quantum is transferred to the electron, elements) bombard the . the rest remains with the scattered quantum. COULOMB (C): The quantity of transported in one second by a current of CONFIDENCE LIMITS: An interval giving one ampere. the lowest and highest estimate of a parameter that is statistically compatible COUNTER: A general designation applied with the data. For a 95% confidence to radiation detection instruments or survey interval, there is a 95% chance that the meters that detect and measure radiation. interval contains the parameter. The signal that indicates an event has been detected is called a count. CONTAMINATION, RADIOACTIVE: Unwanted deposition of radioactive COUNTER, SCINTILLATION: Scintillation material in or on any medium or surface. detection is based on the interaction of The Low concerning Prevention of radiation with substances known as fluors Radiation hazards due to Radioisotopes, (solid or liquid) or scintillators. Excitation of etc permits no contamination greater than the electrons in the fluor leads to 40Bq/cm2 in the radiation controlled area. subsequent emission of (scintillation) which is detected by a photomultiplier tube CONTROLLED AREA: A defined area in and converted into an electronic pulse. The which specific protection measures and pulse magnitude is proportional to the safety provisions are required for energy lost by the incident radiation in the controlling normal exposures or preventing excitation of the fluor. the spread of contamination during normal working conditions, and preventing or COSMIC RADIATION: Penetrating ionizing limiting the extent of potential exposures. radiation, both particulate and electromagnetic, that originates in outer CONVERSION ELECTRON: An electron space. Secondary cosmic rays, formed by ejected from the atom by direct transfer of interactions in the earth's atmospherer.

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the skin, hair loss, and severe pain. Very CRITICALITY: A fission process where the large doses can result in permanent hair production rate equals the neutron loss, scarring, altered skin color, loss rate to absorption or leakage. A deterioration of the affected body part, and is "critical" when it is death of the affected tissue (requiring operating. surgery).

CRITICAL MASS: The minimum amount of CYCLOTRON: where that can achieve a charged particles repeatedly pass an self-sustaining nuclear . electrical acceleration field while they move helically from their source in the centre of CRITICAL ORGAN: The part of the body the machine to the outside. The particles that is most susceptible to radiation are held in the helical level by a strong damage resulting from the specific magnet. A cyclotron is not suitable to exposure conditions under consideration, accelerate electrons. Due to the relativistic taking into account the dose the various mass increase with growing speed the parts of the body receive under the maximum energy achievable with a exposure conditions. cyclotron is limited to about 400 MeV for protons. : The total dose resulting from repeated or continuous DECAY, RADIOACTIVE: Disintegration of exposures of the same portion of the body, the nucleus of an unstable nuclide by or of the whole body, to . spontaneous emission of charged particles and/or photons. CURIE (Ci): The outmoded unit used to quantify activity of radioactive material. DECAY CHAIN (DECAY SERIES): The Defined as 3.7 x 1010 disintegrations per series of decays that certain radioisotopes second. go through before reaching a stable form. For example, the decay chain that begins CUTANEOUS RADIATION SYNDROME with -238 (U-238) ends in lead-206 (CRS): The complex syndrome resulting (Pb-206), after forming isotopes, such as from radiation exposure of more than 200 uranium-234 (U-234), thorium-230 rads to the skin. The immediate effects can (Th-230), -226 (Ra-226), and be reddening and swelling of the exposed radon-222 (Rn-222). area (like a severe ), blisters, ulcers on

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DECAY CONSTANT: The fraction of atoms DETERMINISTIC EFFECT: Injury in undergoing nuclear disintegration per unit populations of cells, characterized by a time. threshold dose and an increase in the severity of the reaction as the dose is DECAY PRODUCTS (DAUGHETR increased further. Also termed tissue PRODUCTS): The isotopes or elements reaction. In some cases, deterministic formed and the particles and high-energy effects are modifiable by post-irradiation electromagnetic radiation emitted by the procedures including biological response nuclei of radionuclides during radioactive modifiers. decay. Also known as "decay chain products" or "progeny" (the isotopes and DETRIMENT: The total harm to health elements). A decay product may be either experienced by an exposed group and its radioactive or stable. descendants as a result of the group’s exposure to a radiation source. Detriment is DECLARED PREGNANT WOMAN: A a multidimensional concept. Its principal woman who is a radiation worker and has components are the stochastic quantities: voluntarily informed her employer, in writing, probability of attributable fatal cancer, of her pregnancy and the estimated date of weighted probability of attributable conception. non-fatal cancer, weighted probability of severe heritable effects, and length of life DECONTAMINATION: The removal of lost if the harm occurs. radioactive contaminants by cleaning and washing with chemicals. DETRIMENT-ADJUSTED RISK: The probability of the occurrence of a stochastic DEPOSITION DENSITY: The activity of a effect, modified to allow for the different radionuclide per unit area of ground. components of the detriment in order to Reported as per square meter express the severity of the or curies per square meter. consequence(s).

DETECTOR: A material or device that is DEUTRIUM: A non-radioactive isotope of sensitive to radiation and can produce a the hydrogen atom that contains a neutron response signal suitable for measurement in its nucleus in addition to the one or analysis. A radiation detection normally seen in hydrogen. A deuterium instrument. atom is twice as heavy as normal hydrogen.

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(DREF): The factor by which the effect DIRTY : A device designed to caused by a specific type of radiation spread radioactive material by conventional changes at low doses or low dose rates explosives when the bomb explodes. A (protracted or fractionated delivery of dose) dirty bomb kills or injures people through as compared to high doses delivered at the initial blast of the conventional high (or acute) dose rates. explosive and spreads radioactive contamination over possibly a large DOSE AND DOSE-RATE area—hence the term “dirty.” Such EFFECTIVENESS FACTOR (DDREF): A could be miniature devices or large truck judged factor that generalizes the usually bombs. A dirty bomb is much simpler to lower biological effectiveness (per unit of make than a true . dose) of radiation exposures at low doses and low dose rates as compared with DNA DAMAGE SIGNALLING: Interacting exposures at high doses and high dose biochemical processes that recognize and rates. respond to DNA damage in cells, e.g., by causing the arrest of the reproductive cell DOSE COEFFICIENT: Used as a synonym cycle and/or apoptosis. Molecules such as for dose per unit intake of a radioactive ATM, CHK1, , and p21 are known to be substance, but sometimes also used to involved in the processes. describe other coefficients linking quantities or concentrations of activity to doses or DOSE: Short name for absorbed dose (1 dose rates, such as the external dose rate Gy = 1 J/kg) and also for , at a specified distance above a surface with effective dose, and weighted dose (1 Sv = a deposit of a specified activity per unit 1 J/kg). Definitions of low, medium, and area of a specified radionuclide. high doses vary widely in the literature. For the purposes of this report, dose levels DOSE CONSTRAINT: A prospective and have been defined as follows: Low dose: source-related restriction on the individual 0-100 mGy (mSv), Medium dose: In excess dose from a source, which provides a basic of 100 mGy up to a maximum of 1 Gy, High level of protection for the most highly dose: In excess of 1 Gy up to the very high exposed individuals from a source, and total doses used in radiation (on serves as an upper bound on the dose in the order of 20–60 Gy). optimization of protection for that source. For occupational exposures, the dose DOSE-RATE EFFECTIVENESS FACTOR constraint is a value of individual dose used

8 GLOSSARY – Nagasaki University Center for Frontier Life Sciences to limit the range of options considered in is worn. the process of optimization. For public exposure, the dose constraint is an upper DOSE LIMIT: The value of the effective bound on the annual doses that members dose or the equivalent dose to individuals of the public should receive from the from planned exposure situations that shall planned operation of any controlled source. not be exceeded.

DOSE EQUIVALENT, H: The product of D DOSE RATE: Dose per unit time (Gy/min and Q at a point in tissue, where D is the or Sv/min, for example). absorbed dose and Q is the quality factor for the specific radiation at this point, thus: DOSE RECONSTRUCTION: A scientific H = DQ. The unit of dose equivalent is joule study that estimates doses to people from per kilogram (J kg-1), and its special name releases of radioactivity or other pollutants. is sievert (Sv). The dose is reconstructed by determining the amount of material released, the way DOSE EQUIVALENT, DIRECTIONAL, people came in contact with it, and the H’(d, Ω): The dose equivalent at a point in amount they absorbed. a radiation field that would be produced by the corresponding expanded field in the DOSE MODIFYING FACTOR (DMF): The ICRU sphere at a depth, d, on a radius in a ratio of doses with and without modifying specified direction, Ω. The unit of agents, causing the same level of biological directional dose equivalent is joule per effect. kilogram (J kg-1) and its special name is sievert (Sv). DOSIMETER, PERSONAL: A small pocket-sized dosimeter used for monitoring

DOSE EQUIVALENT, PERSONAL, Hp(d): radiation exposure of personnel. An operational quantity. The dose equivalent in soft tissue (commonly : Assessment (by interpreted as the ‘ICRU sphere’) at an measurement or calculation) of radiation appropriate depth, d, below a specified dose. point on the human body. The unit of personal dose equivalent is joule per DOUBLING DOSE (DD): The dose of kilogram (J kg-1) and its special name is radiation (Gy) that is required to produce as sievert (Sv). The specified point is usually many heritable as those arising given by the position where the individual’s spontaneously in a generation.

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Number of persons average effective DS02: Dosimetry System 2002, a system dose. Unit is person-Sv (special name used for estimating gamma and neutron with collective dose). exposure under a large variety of situations and which allows the calculation of EFFECTIVE DOSE, COMMITTED, E(τ): absorbed dose to specific organs for The sum of the products of the committed members of the Life Span Study. DS02 organ or tissue equivalent doses and the improved on the DS86 dose system. appropriate tissue weighting factors (wΤ), where τ is the integration time in years DTPA: Diethylenetriamine pentaacetate; following the intake. The commitment chelators. Chelators are organic period is taken to be 50 years for adults, compounds capable of integrating metal and to age 70 years for children. in the organic molecule in such a way that the metal ion loses its chemical ELECTROMAGNETIC RADIATION: A properties essential for its biological spectrum of discrete energy emissions behaviour and can therefore be excreted such as radio , , more rapidly from the body. Thus, effective light, visual light, X-rays, gamma decorporation agents in the form of rays, etc, having no charge or mass, often Ca-DTPA and Zn-DTPA - in particular for called photons or quanta. - are available. ELECTRON: An elementary particle with a EFFECTIVE DOSE, E: The unit electrical charge and a mass 1/1837 tissue-weighted sum of the equivalent that of the proton. Electrons surround the doses in all specified tissues and organs of atom's positively charged nucleus and the body, given by the expression: determine the atom's chemical properties.

ELECTRON CAPTURE: A type of where HΤ or wRDT,R is the equivalent dose radioactivity in which an atomic electron is in a tissue or organ, T, and wΤ is the tissue absorbed by the nucleus, and is often weighting factor. The unit for the effective followed by gamma-ray emission. dose is the same as for absorbed dose, J kg-1, and its special name is sievert (Sv). ELECTRON VOLT (eV): A special unit of 1Sv=100rem. energy: 1 eV = 1.6 × 10－19J = 1.6 × 10－12 erg; 1 eV is equivalent to the energy gained EFFECTIVE DOSE, COLLECTIVE: by an electron in passing through a

10 GLOSSARY – Nagasaki University Center for Frontier Life Sciences potential difference of 1 V; 1 keV=1000 eV; ENERGY FLUX DENSITY (ENERGY 1 MeV = 1,000,000 eV. FLUENCE RATE): The sum of the energies, exclusive of rest energies, of all particles EMERGENCY: A non-routine situation or passing through a unit cross-sectional area event that necessitates prompt action per unit time. primarily to mitigate a hazard or adverse consequences for human health and safety, ENERGY LEVELS: Discrete set of quality of life, property or the environment. quantized energies states within a given This includes situations for which prompt (or atom itself). action is warranted to mitigate the effects of a perceived hazard. Actions in case of EPIDEMIOLOGY: The study of the emergency should be clarified and determinants of the of disease in informed to radiation workers. humans. The two main types of epidemiologic studies of chronic disease ENERGY, AVERAGE PER ION PAIR: The are cohort (or follow-up) studies and average energy expended by a charged case-control studies. particle in a gas per ion pair produced. For most radiological calculations, this value EQUIVALENT DOSE, HT: The dose in a has been normalized to 33.73 eV. tissue or organ T given by:

ENERGY, BINDING: The energy represented by the difference in mass where DT,R is the mean absorbed dose between the sum of the component parts from radiation R in a tissue or organ T, and and the actual mass of the nucleus. wR is the radiation weighting factor. Since

wR is dimensionless, the unit for the ENERGY, EXCITATION: The energy equivalent dose is the same as for required to change a system from its lowest absorbed dose, J kg-1, and its special name energy state (ground state) to an excited is sievert (Sv). state. EQUIVALENT DOSE, COMMITTED,

ENERGY FLUENCE: The sum of the HΤ(τ): The time integral of the equivalent energies, exclusive of rest energies, of all dose rate in a particular tissue or organ that particles passing through a unit will be received by an individual following cross-sectional area. intake of radioactive material into the body by a Reference Person, where τ is the

11 GLOSSARY – Nagasaki University Center for Frontier Life Sciences integration time in years. per Gy or per Sv.

ERRORS, RANDOM: Errors that vary in a EXCITED STATE: The state of an atom or non-reproducible way around a limiting nucleus when it possesses more than its mean. These errors can be treated normal energy. The excess energy is statistically by use of the laws of probability. usually released eventually as a . ERRORS, SYSTEMIC: Errors that are reproducible and tend to bias a result in EXCLUSION: The deliberate exclusion of a one direction. Their causes can be particular category of exposure from the assigned, at least in principle, and they can scope of an instrument of regulatory have constant and variable components. control. Generally, these errors cannot be treated statistically. EXEMPTION: The determination by a regulatory body that a source or practice ERYTHEMA: An abnormal redness of the activity involving radiation need not be skin due to distention of the capillaries with subject to some or all aspects of regulatory blood. It can be caused by many different control. agents of which , drugs, ultraviolet rays, and ionizing radiation (dose of 10 Sv) are EXPOSED INDIVIDUALS: The ICRP the most common. distinguishes between three categories of exposed individuals: workers (informed EXCESS ABSOLUTE RISK (EAR): The individuals), the public (general individuals), rate of disease incidence or mortality in an and patients, including their comforters and exposed population minus the carers. corresponding disease rate in an unexposed population. The excess EXPOSURE (C/kg): A measure of the absolute risk is often expressed as the ionization produced in air by X or gamma additive excess rate per Gy or per Sv. radiation. It is the sum of the electrical charges on all ions of one sign produced in EXCESS RELATIVE RISK (ERR): The rate air when all electrons liberated by photons of disease in an exposed population in a volume element of air are completely divided by the rate of disease in an stopped in air, divided by the mass of the unexposed population, minus 1.0. This is air in the volume element. The SI unit of often expressed as the excess relative risk Coulombs per kilogram replaces the

12 GLOSSARY – Nagasaki University Center for Frontier Life Sciences outmoded unit. exposure.

EXPOSURE, ACUTE: An exposure to EXPOSURE, OCCUPATIONAL: Exposure radiation that occurred in a matter of incurred by workers in the course of their minutes rather than in longer, continuing , with the exception of 1) excluded exposure over a period of time. exposures and exposures from exempt activities involving radiation or exempt EXPOSURE, CATEGORIES OF: The ICRP sources; 2) any medical exposure; and 3) distinguishes between three categories of the normal local natural background radiation exposure: occupational, public, radiation. and medical exposures of patients. EXPOSURE, POTENTIAL: Exposure that EXPOSURE, CHRONIC: Exposure to a is not expected to be delivered with substance over a long period of time, certainty but that may result from an possibly resulting in adverse health effects. accident at a source or an event or sequence of events of a probabilistic nature, EXPOSURE, EXTERNAL: Exposure to including equipment failures and operating radiation outside of the body. errors.

EXPOSURE, FRACTIONATED: Exposure EXPOSURE, PRENATAL: Radiation to radiation that occurs in several small exposure to an embryo or fetus while it is acute exposures, rather than continuously still in its mother’s womb. At certain stages as in a chronic exposure. of the pregnancy, the fetus is particularly sensitive to radiation and the health EXPOSURE, INTERNAL: Exposure to consequences could be severe above 5 radioactive material taken into the body. rads, especially to brain function.

EXPOSURE, MEDICAL: Exposure EXPOSURE, PUBLIC: Exposure incurred incurred by patients as part of their own by members of the public from radiation medical or dental diagnosis or treatment; sources, excluding any occupational or by persons, other than those occupationally medical exposure and the normal local exposed, knowingly, while voluntarily natural background radiation. helping in the support and comfort of patients; and by volunteers in a program of EXPOSURE, WHOLE BODY: An exposure biomedical research involving their of the body to radiation, in which the entire

13 GLOSSARY – Nagasaki University Center for Frontier Life Sciences body, rather than an isolated part, is into two roughly equal parts (which are irradiated by an external source. nuclei of lighter elements), accompanied by the release of a relatively large amount of EXPOSURE PATHWAY: A route by which a energy in the form of of the radionuclide or other toxic material can two parts and in the form of emission of enter the body. The main exposure routes neutrons and gamma rays. are inhalation, ingestion, absorption through the skin, and entry through a cut or FISSION MATERIAL: Any material in wound in the skin. which neutrons can cause a fission reaction. The three primary fissile materials are EXPOSURE SITUATIONS, EXISTING: A uranium-233, uranium-235, and situation that already exists when a plutonium-239. decision on control has to be taken, including natural background radiation and FISSION PRODUCTS: Nuclei formed by residues from past practices that were the fission of heavy elements. They are of operated outside the ICRP medium atomic weight and almost all are recommendations. radioactive.

EXPOSURE SITUATIONS, PLANNED: FLUENCE, PARTICLE, Φ: The quotient of Everyday situations involving the planned dN by da, where dN is the number of operation of sources including particles incident upon a small sphere of decommissioning, disposal of radioactive cross-sectional area da. waste and rehabilitation of the previously occupied land. Practices in operation are FUSION: A reaction in which at least one planned exposure situations. heavier, more stable nucleus is produced from two lighter, less stable nuclei. FILM BADGE: Photographic film used for Reactions of this type are responsible for measurement of ionizing radiation the release of energy in . exposure for personnel monitoring purposes. The film badge may contain two GAMMA RADIATION: Short- or three films of differing sensitivities, and it electromagnetic radiation of nuclear origin, may contain a filter that shields part of the similar to X-rays but usually of higher film from certain types of radiation. energy (100 keV to several MeV).

FISSION: The splitting of a heavy nucleus GAS-FILLED DETECTOR: The most

14 GLOSSARY – Nagasaki University Center for Frontier Life Sciences common type of radiation detector. This composed of a gas filled hollow tube instrument works on the principle that as containing two coaxial electrodes that radiation passes through air or a specific discharge and recharge following ionizing gas, ionization of the molecules in the air events. occur. When a high voltage is placed between two areas of the gas filled space, GENERATOR: Device from which a the positive ions will be attracted to the progeny nuclide is eluted from an ion negative side of the detector (the cathode) exchange column containing a parent and the free electrons will travel to the radionuclide, which is long-lived compared positive side (the anode). These charges to the progeny. are collected by the anode and cathode which then form a very small current in the GENETIC EFFECT OF RADIATION: The wires going to the detector. By placing a radiation induced change in the DNA of very sensitive current measuring device germ cells resulting in the passing of the between the wires from the cathode and altered genetic information to future anode, the small current measured and generations. displayed as a signal. The more radiation which enters the chamber, the more current GEOMETRY FACTOR: The fraction of the displayed by the instrument. Many types of total solid angle about a radiation source gas-filled detectors exist, but the two most that is subtended by the face of the common are the ion chamber used for sensitive volume of a detector. measuring large amounts of radiation and the Geiger-Muller or GM detector used to GERM CELLS: Reproductive cells such as measure very small amounts of radiation. the sperm and egg and their progenitor cells. GAS FLOW COUNTER: A proportional counter with its flowing filling gas GLASS BADGE: Phosphate glass continuously replaced by new gas. Thus, dosimeter. Measuring device to determine the ingress of air is avoided or ingressed air the dose. The radio-photoluminescence expelled. effect which is the property of certain substances to emit fluorescent light of GEIGER MUELLER (GM) COUNTER: The greater length upon irradiation with major component of laboratory survey ultraviolet light when previously exposed to meters, which function as incident radiation ionizing radiation, is used to determine the detectors. A Geiger-Mueller tube is dose. Silver-activated metaphosphate

15 GLOSSARY – Nagasaki University Center for Frontier Life Sciences glasses - glasses made of alkaline and radionuclide has its own unique half-life. alkaline earth phosphates with some percent of silver metaphosphate - show this HALF VALUE LAYER (HVL): The photoluminescence effect for example. The thickness of a specified substance which, intensity of the fluorescent light is when introduced into the path of a given proportional over wide areas of the beam of X or gamma radiation, reduces the irradiated dose. intensity of the beam by one half.

GONAD DOSE: Radiation dose at the HEAVY WATER: Deuterium oxide, D2O; gonads (testicles and ovaries). water containing two deuterium atoms instead of the two light hydrogen atoms. GRAY (Gy): The SI unit of absorbed dose Natural water contains one deuterium atom that is equal to one joule per kilogram. per 6,500 molecules H2O. D2O has a low Replaces the (1Gy=100Rad). neutron absorption cross-section. It is therefore applicable as a moderator in GROWTH FACTORS: Molecules that act natural-uranium-fuelled reactors. to control cell reproduction and proliferation/differentiation of a population HEPA FILTER: High-efficiency particulate of cells. air filter to separate dry aerosols; in Germany suspended matter filter of special HALF-LIFE, BIOLOGICAL (BHL): The class S, frequently called „absolute time required for the body to eliminate one membrane filter“. half of an administrated dosage of any substance by regular process of HIGH-LET RADIATION: Neutrons or heavy, elimination. charged particles, such as protons or alpha particles, that produce ionizing events HALF-LIFE, EFFECTIVE (EHL): Time densely spaced on a molecular scale (e.g., required for a radioactive element in a living L > 10 keV/μm) to be diminished 50% as a result of the combined action of physical half-life HORMESIS: Some physical or chemical (PHL) and biological elimination (BHL). agents have one effect at high doses and the reverse effect at low doses. This HALF-LIFE, PHYSICAL (PHL): Time phenomenon is known as hormesis. It required for a radioactive substance to lose probably results from the activation of 50% of its activity by decay. Each defense mechanisms. Hormesis is

16 GLOSSARY – Nagasaki University Center for Frontier Life Sciences observed with several drug molecules that induction of an altered cellular state are toxic at high doses, but which can have characterized by a persistent increase over a beneficial protective effect at low doses. many generations in the spontaneous rate of or other genome-related HOT: A term used in for changes. "highly active". : Radioactivity HOT CELL: Highly shielded tight casing in that is created by bombarding a substance which highly radioactive substances can be with neutrons in a reactor or with charged remotely handled by manipulators particles produced by particle accelerators. observing the processes through lead-glass windows so that there is no INES (INTERNATIONAL NUCLEAR hazard to personnel. EVENT SCALE): A scale with seven levels proposed by the IAEA to evaluate the ICRP (INTERNATIONAL COMMISSION events occurring in nuclear installations OF RADIOLOGICAL PROTECTION): An according to international uniform criteria, independent international organization that in particular with regard to the aspect of provides recommendations and guidance hazards to the population. The upper levels on protection against ionizing radiation. (4 to 7) include accidents, the lower levels (1 to 3) anomalies and incidents. Notifiable ICRU (INTERNATIONAL COMMISSION events of no safety-related or radiological ON RADIATION UNITS AND significance according to the international MEASUREMENTS): An independent scale are designated as „below the international organization that provides scale“ or "Level 0". recommendations and guidance on radiation quantities, units, and INGESTION: 1) The act of swallowing; 2) In measurements. the case of radionuclides or chemicals, swallowing radionuclides or chemicals by INCIDENCE: The rate of occurrence of a eating or drinking. disease within a specified period of time, often expressed as a number of cases per INHALATION: 1) The act of breathing in; 2) 100,000 individuals per year. Also, In the case of radionuclides or chemicals, incidence rate. breathing in radionuclides or chemicals.

INDUCED GENOMIC INSTABILITY: The INTAKE: Activity that enters the body

17 GLOSSARY – Nagasaki University Center for Frontier Life Sciences through the respiratory tract or the extending along the axis. When a photon or gastrointestinal tract or the skin. A single a charged particle enters the chamber, it intake by inhalation or ingestion, taken to converts some of the gas molecules to occur instantaneously is called “Acute positive ions and electrons; under the intake”, whereas an intake over a specified influence of the electric field, these particles period of time is called “Chronic intake”. migrate to the wall and the wire, respectively, and cause an observable INTERNAL CONVERSION: Direct transfer pulse of current to flow through the circuit of excess energy to one of its own orbiting joining these elements. electrons, thereby ejecting the electron from the atom (conversion electron). It IONIZATION ENERGY: The energy always accompanies the predominant required to remove one electron from an process of gamma emission to some atom giving rise to an ion pair. In air, the extent. average ionization energy is 33.73 eV.

IN UETRO: In the womb (i.e., before birth). IONIZING RADIATION: Radiation sufficiently energetic to dislodge electrons ION: An atomic particle that is electrically from an atom, thereby producing an ion pair. charged, either negative or positive. Ionizing radiation includes X- and gamma radiation, electrons (beta radiation), alpha IONIZATION: The process of adding one or particles (helium nuclei), and heavier more electrons to, or removing one or more charged atomic nuclei. Neutrons ionize electrons from, atoms or molecules, indirectly by first colliding with components thereby creating ions. High temperatures, of atomic nuclei. electrical discharges, or nuclear radiation can cause ionization. IRRADIATION: Subjection to radiation.

IONIZATION CHAMBER: Radiation ISOMER: One of several nuclides with the detector used for determining the intensity same number of neutrons and protons of a beam of radiation or for counting capable of existing for a measurable time in individual charged particles. The device different nuclear energy states. may consist of a gas-filled, cylindrical container in which an electric field is ISOMETRIC TRANSITION: A mode of maintained by impressing a voltage that radioactive decay where a nucleus goes keeps the wall negative relative to a wire from a higher to a lower energy state. The

18 GLOSSARY – Nagasaki University Center for Frontier Life Sciences mass number and the atomic number are unchanged. KERMA (KINETIC ENERGY RELEASED IN MATERIAL, K: The quotient of the sum

ISOTOPE: A given element have the same of the kinetic energies, dEtr, of all charged atomic number (same number of protons in particles liberated by uncharged particles in their nuclei) but different atomic weights a mass dm of material, and the mass dm of (different number of neutrons in their that material. nuclei). Uranium-238 and uranium-235 are isotopes of uranium. Kerma is defined as a non-stochastic JUSTIFICATION: The process of quantity and dEtr is the expectation value determining whether either (1) a planned of the sum of the kinetic energies. The unit activity involving radiation is, overall, for kerma is joule per kilogram (J kg-1) and beneficial, i.e. whether the benefits to its special name is gray (Gy). individuals and to society from introducing or continuing the activity outweigh the harm LABELLED COMPOUND: A compound (including radiation detriment) resulting consisting, in part, of molecules made up of from the activity; or (2) a proposed remedial one or more atoms distinguished by action in an emergency or existing non-natural isotopic composition (either exposure situation is likely, overall, to be radioactive or stable isotopes). beneficial, i.e., whether the benefits to individuals and to society (including the LATENT PERIOD: The period or state of reduction in radiation detriment) from seeming inactivity between the time of introducing or continuing the remedial exposure of tissue to an injurious agent action outweigh its cost and any harm or such as radiation, and the presentation of damage it causes. the associated pathology.

JOULE (J): The work done when the point LD50: Dose that is lethal for half of the of application of a of one newton is exposed individuals. displaced a distance of one meter in the direction of the force. LIFE SPAN STUDY (LSS): The long-term cohort study of health effects in the K-CAPTURE: The capture by an atom's Japanese atomic bomb survivors in nucleus of an orbital electron from the first Hiroshima and Nagasaki. K-shell surrounding the nucleus.

19 GLOSSARY – Nagasaki University Center for Frontier Life Sciences

LINEAR ACCELERATOR: A long straight dose-response for which any dose greater tube in which particles (mostly electrons or than zero has a positive probability of protons) are accelerated by electrostatic producing an effect (e.g., mutation or fields or electromagnetic waves and thus cancer). The probability is calculated either achieve very high energies. from the slope of a linear (L) model or from the limiting slope, as the dose approaches LINEAR DOSE RESPONSE: A statistical zero, of a linear-quadratic (LQ) model. model that expresses the risk of an effect (e.g., disease or abnormality) as being LOCAL RADIATION INJURY: Acute proportional to dose. radiation exposure (more than 1,000 rads) to a small, localized part of the body. Most (LET): The local radiation injuries do not cause death. rate at which an incident particle transfers However, if the exposure is from energy as it travels through matter. The unit penetrating radiation (neutrons, X-rays, or is keV per micron of path traveled, and is gamma rays), internal organs may be often given in J m-1. damaged and some symptoms of (ARS), including death, LINEAR-QUADRATIC DOSE RESPONSE may occur. Local radiation injury invariably (LQ MODEL): A statistical model that involves skin damage, and a skin graft or expresses the risk of an effect (e.g., other surgery may be required. disease, death, or abnormality) as the sum of two components, one proportional to LOW CONCERNING PREVENSION OF dose (linear term) and the other one RADIATION HAZARDS DUE TO proportional to the square of dose RADIOISOTOPES, ETC.: The Japanese (quadratic term). Low established in 1957, which regulates the use, sale, lease, disposal and other LIQUID handling of radioisotopes, the use of (LSC): Scintillation counter in which the radiation generating equipment, and the scintillator is an organic liquid (e.g. diphenyl disposal and other handling of the articles oxazole, dissolved in toluene). Preferred contaminated by radioisotopes to prevent detection and measuring device for the radiation hazards. low-energetic beta radiation of tritium and carbon-14. LOW ENERGY GAMMA SCINTILLATOR (LEGS): A detection system that utilizes an LNT MODEL: Linear no-threshold alkali halide crystal photomultiplier

20 GLOSSARY – Nagasaki University Center for Frontier Life Sciences arrangement to detect low energy gamma MORTALITY (RATE): The frequency at and x-ray radiation. which people die from a disease (e.g., a specific cancer), often expressed as the LOW FOR THE REGULATION OF number of deaths per 100,000 population NUCLEAR SOURCE MATERIAL, per year. NUCLEAR AND REACTORS: The Japanese Low established in 1957, which MILTI-CHANNEL ANALYZER: Pulse enforces the necessary regulations on amplitude analyser sorting the pulses of manufacture, processing, strage, energy-proportional detectors according to reprocessing and disposal activities of the amplitude and thus the radiation energy nuclear source materials, fuel materials and recording them in the corresponding and nuclear reactors. channel. Multi-channel analysers have more than 8,000 channels

LOW-LET RADIATION: X-rays and NCRP (NATIONAL COUNCIL ON gamma rays or light, charged particles, AND such as electrons, that produce sparse MEASUREMENTS): U.S. Council ionizing events far apart on a molecular commissioned to formulate and scale (e.g., L < 10 keV/μm). disseminate information, guidance, and recommendations on radiation protection MAXIMUM PERMISSIBLE and measurements. CONCENTRATION: Limits set on water and air concentrations of radionuclides, NEOPLASTIC: Pertaining to the pathologic which yield maximum permissible body process resulting in the formation and burden values and their corresponding growth of an abnormal mass of tissue. organ dosages. : An electrically neutral particle META ANALYSIS: An analysis of with negligible mass. It is produced in many epidemiologic data from several studies nuclear reactions such as in . based on data included in publications. NEUTRON: One of the basic particles MONTE CARLO CALCULATION: The which make up an atom. A neutron and a method for evaluation of a probability proton have about the same weight, but the distribution by means of random sampling. neutron has no electrical charge.

21 GLOSSARY – Nagasaki University Center for Frontier Life Sciences

NEUTRON, FAST: Neutron with a kinetic radiation or are used. energy of more than 0.1 MeV. NON-IONIZING RADIATION: Radiation NEUTRON, INTERMEDIATE: Neutron with that has lower energy levels and longer an energy beyond that of a slow neutron, than ionizing radiation. It is not however lower than that of a fast neutron; strong enough to affect the structure of generally within the range of 10 and atoms it contacts but is strong enough to 100,000 eV. heat tissue and can cause harmful biological effects. Examples include radio NEUTRON, THERMAL: Neutrons in waves, microwaves, visible light, and thermal equilibrium with the ambient from a heat lamp. medium. Thermal neutrons most probably have a neutron velocity of 2200 m/s at NORM (NATURALLY OCCURING 293.6 K corresponding to an energy of RADIOACTIVE MATERIAL): Radioactive 0.0253 eV. Fast neutrons as generated material containing no significant amounts during are decelerated by of radionuclides other than naturally collisions with the atoms of the moderator occurring radionuclides. Material in which material (usually water, heavy water or the activity concentrations of the naturally graphite) to , they are occurring radionuclides have been 'thermalized'. changed by some process are included in NORM. NOMINAL RISK COEFFICIENT: Sex averaged and age at exposure averaged NPT (NON-PROLIFERATION TREATY): lifetime risk estimates for a representative The aim of the international Treaty on the population. Non-proliferation of Nuclear Weapons and the resulting monitoring is NON-CANCER DISEASES, RADIATION the timely detection of nuclear material INDUCED: Somatic diseases other than diversion for the manufacture of nuclear cancer, e.g., cardiovascular disease and weapons or deterrence of such deviation cataracts. through the risk of detection. Corresponding monitoring in Germany is NON-DESTRUCTIVE TESTING: Testing performed by Euratom and the for hidden defects in material using International Atomic Energy Agency. methods which do not damage or destroy the test pieces. Frequently X-rays, gamma NUCLEAR ENERGY: The heat energy

22 GLOSSARY – Nagasaki University Center for Frontier Life Sciences produced by the process of nuclear fission NUCLEON: A constituent of the nucleus; within a nuclear reactor or by radioactive that is, a proton or a neutron. decay. NUCLEUS: The core of the atom, where : Minute particles of most of its mass and all of its positive radioactive debris that descend slowly from charge is concentrated. Except for the after a . hydrogen, it consists of protons and neutrons. CYCLE: The steps involved in supplying fuel for NUCLEUS, STABLE: Non-radioactive . It can include mining, milling, nucleus. The nucleus of an atom in which isotopic enrichment, fabrication of fuel the among its particles are balanced. elements, use in reactors, chemical reprocessing to recover the fissile material NUCLEUS, UNSTABLE: Nucleus that remaining in the spent fuel, reenrichment of contains an uneven number of protons and the fuel material refabrication into new fuel neutrons and seeks to reach equilibrium elements, and waste disposal. between them through radioactive decay

NUCLEAR MEDICINE: Application of open NUCLlDE: A species of atom in which the or enclosed radioactive substances in nuclear constitution is specified by the medicine for diagnostic or therapeutic number of protons (Z), number of neutrons purposes. In functional (N), and the energy content; or alternately diagnostics and localization diagnostics is by the atomic number (Z), mass number A distinguished. = (N + Z), and atomic mass.

NUCLEAR POWER : An electrical ODDS RATIO: The odds of being exposed generating facility using a nuclear reactor among diseased persons divided by the as its power (heat) source. odds of being exposed among non-diseased persons. NUCLEAR REACTOR: A device in which a fission chain reaction can be initiated, OPERATIONAL QUANTITIES: Quantities maintained, and controlled. Its essential used in practical applications for monitoring components are fissionable fuel, moderator, and investigating situations involving shielding, control rods, and coolant. external exposure. They are defined for measurements and assessment of doses in

23 GLOSSARY – Nagasaki University Center for Frontier Life Sciences the body. In , no properties are placed one under the other operational dose quantities have been yielding groups or families of elements. defined which directly provide an Within each group, there is a variation of assessment of equivalent or effective dose. chemical and physical properties but, in Different methods are applied to assess the general, there is a similarity of chemical equivalent or effective dose due to behavior within each group. radionuclides in the human body. They are mostly based on various activity PERSONNEL MONITORING: The use of measurements and the application of portable survey meters to determine the biokinetic models (computational models). presence or amount of radioactive contamination on an individual, or the use OPTIMISATION (OF PROTECTION): The of a dosimeter to determine an individual's process of determining what level of radiation dose. protection and safety makes exposures, and the probability and magnitude of PHOTO-CATHODE: Cathode where potential exposures, as low as reasonably electrons are released by the photoelectric achievable (ALARA), economic and effect. societal factors being taken into account. PHOTOELECTRIC EFFECT: Interaction PAIR PRODUCTION: Interaction of of electromagnetic radiation with energy-rich electromagnetic radiation with matter. The photon transfers its matter. If the energy of a radiation is greater energy to the shell electron of the than 1.02 MeV and thus greater than atom. The electron receives kinetic double the rest mass of an electron (me,0= energy which is equal to the energy of 0.511 MeV), it is possible to generate an the photon reduced by the binding electron- pair. energy of the electron.

PARENT: A radionuclide that upon PHOTOMULTIPLIER: Electron multiplier radioactive decay or disintegration yields a tube that utilizes the multiplication of specific nuclide (the decay product or electrons by secondary emission to daughter). measure low light intensities. The tube utilizes a photosensitive cathode, that is, a PERIODOC TABLE: An arrangement of cathode that emits electrons when light chemical elements in order of increasing strikes it, followed by a series of additional atomic number. Elements of similar electrodes, or dynodes, each at a

24 GLOSSARY – Nagasaki University Center for Frontier Life Sciences successively higher positive potential so charge. that it will attract electrons given off by the previous dynode. PREVALENCE: The number of cases of a disease in existence at a given time per unit PHOTON: A quantized amount of of population, usually 100,000 persons. electromagnetic energy, which at times displays particle characteristics. An PROJECTED DOSE: The dose that would electromagnetic quantum whose energy be expected to be incurred if no protective (Eph) equals the product of the Planck measure(s) – were to be taken. constant (h) and its frequency (n). With the convenient units eV and s, and with the PROPORTIONAL COUNTER: A radiation wave length λ in μm: Eph = 4.136 × 10－ instrument in which an electronic detection 15ν = 1.24/λ. system receives pulses that are proportional to the number of ions formed PLUME: The material spreading from a in a gas-filled tube by ionizing radiation. particular source and traveling through environmental media, such as air or ground PROTECTION, PRINCIPLES OF: A set of water. For example, a plume could describe principles that apply equally to all the dispersal of particles, gases, , controllable exposure situations: the and aerosols in the atmosphere, or the principle of justification, the principle of movement of contamination through an optimisation of protection, and the principle aquifer (For example, dilution, mixing, or of application of limits on maximum doses adsorption onto soil). in planned situations.

POCKET DOSIMETER: A small ionization PROTON: One of the basic particles which detection instrument worn by an individual makes up an atom. The proton is found in that directly measures the ionizing radiation the nucleus and has a positive electrical exposure. charge equivalent to the negative charge of an electron and a mass similar to that of a POOLED ANALYSIS: An analysis of neutron: a hydrogen nucleus. epidemiologic data from several studies based on original data from the studies. QUADRATIC-DOSE MODEL: A model that assumes that the excess risk is POSITRON: A particle equal in mass to an proportional to the square of the dose. electron and having an equal but positive

25 GLOSSARY – Nagasaki University Center for Frontier Life Sciences

QUALITY FACTOR: The principal dose The basis for radiation protection at each modifying factor which is based on the radiation facility, in which the basic collision stopping power of an incident concepts of radiation protection, the particle and was employed to derive the safety-control structure, and specific dose equivalent from the absorbed dose. practices that radiation workers must Quality factor is now superseded by the adhere to, are all spelled out. radiation weighting factor in the definition of equivalent dose, but it is still used in RADIATION PROTECTION calculating the operational dose equivalent SUPERVISOR: Personnel responsible for quantities used in the monitoring. supervising efforts, who are legally appointed at any establishment where RAD: A special unit of absorbed dose, now radiation or radioisotopes are handled in replaced by the SI unit gray. 1 rad = 0.01 the course of using, selling, leasing, or Gy = 100 erg/g. disposing of them.

RADIATION: Energy emitted in the form of RADIATION SICKNESS: The complex of waves or particles by radioactive atoms as symptoms characterizing the disease a result of radioactive decay or produced known as radiation injury, resulting from by artificial means, such as X-ray excessive exposure (greater than 200 rads generators. or 2 gray) of the whole body (or large part) to ionizing radiation. The earliest of these RADIATION DETRIMENT: A concept used symptoms are nausea, fatigue, vomiting, to quantify the harmful health effects of and diarrhea, which may be followed by radiation exposure in different parts of the loss of hair (epilation), hemorrhage, body. It is defined by the ICRP as a function inflammation of the mouth and throat, and of several factors, including incidence of general loss of energy. In severe cases, radiation-related cancer or heritable effects, where the radiation exposure has been lethality of these conditions, quality of life, approximately 1,000 rad (10 gray) or more, and years of life lost owing to these death may occur within two to four weeks. conditions. RADIATION SOURCE: Usually a sealed RADIATION PROTECTION RULES: source of radiation used in teletherapy and Specific rules for the implementation of industrial , as a power source radiation control and the prevention of for batteries (as in use in space craft), or in radiation hazards at each radiation facility. various types of industrial gauges.

26 GLOSSARY – Nagasaki University Center for Frontier Life Sciences

Machines, such as accelerators and member is called the end product. radioisotope generators, and natural radionuclides may be considered sources. : Materials which are radioactive and for which there is no

RADIATION WEIGHTING FACTOR, wR: A further use. dimensionless factor by which the organ or tissue absorbed dose is multiplied to reflect RADIOACTIVE WASTE, HIGH LEVEL: the higher biological effectiveness of The radioactive material resulting from high-LET radiations compared with reprocessing. This can low-LET radiations. It is used to derive the include liquid waste directly produced in equivalent dose from the absorbed dose reprocessing or any solid material derived averaged over a tissue or organ. from the liquid wastes having a sufficient concentration of fission products. Other RADIATION WARNING SYMBOL: An radioactive materials can be designated as officially prescribed symbol (a magenta high-level waste, if they require permanent trefoil) on a yellow background that must be isolation. displayed where certain quantities of radioactive materials are present or where RADIOACTIVE WASTE, LOW LEVEL: certain doses of radiation could be Radioactively contaminated industrial or received. research waste such as paper, rags, plastic bags, medical waste, and water-treatment RADIOACTIVE MATERIAL: Material residues. It is waste that does not meet the designated in national law or by a criteria for any of three other categories of regulatory body as being subject to radioactive waste: spent nuclear fuel and regulatory control because of its high-level radioactive waste; transuranic radioactivity, often taking account of both radioactive waste; or uranium mill tailings. activity and activity concentration. Its categorization does not depend on the level of radioactivity it contains. RADIOACTIVE SERIES: A succession of nuclides, each of which transforms by RADIOACTIVITY: The property of certain radioactive disintegration into another unstable nuclides to spontaneously nuclide until a stable nuclide results. The undergo nuclear transformations that result first member is called the parent, the in the emission of ionizing radiations. See intermediate members are called decay (or also “ACTIVITY”. daughter) products, and the final stable

27 GLOSSARY – Nagasaki University Center for Frontier Life Sciences

RADIOGRAPHY: 1) Medical: The use of of cells, tissues, organs and to (such as x-rays and gamma damage induced by radiation. rays) to image body systems. 2) Industrial: The use of radioactive sources to RADIOSENSITIVITY: Relative photograph internal structures, such as susceptibility of cells, tissue, organs and turbine blades in jet engines. A sealed organisms to damage induced by radiation. radiation source, usually iridium-192 (Ir-192) or cobalt-60 (Co-60), beams REFERENCE LEVEL: In emergency or gamma rays at the object to be checked. existing controllable exposure situations, Gamma rays passing through flaws in the this represents the level of dose or risk, metal or incomplete welds strike special above which it is judged to be inappropriate photographic film (radiographic film) on the to plan to allow exposures to occur, and opposite side. below which optimization of protection should be implemented. The chosen value RADIOISOTOPE: A radioactive atomic for a reference level will depend upon the species of an element with the same prevailing circumstances of the exposure atomic number and usually identical under consideration. chemical properties. A synonym for radionuclide. REFERENCE MAN: A person assumed to have the anatomical and physiological RADIOLOGY: The branch of medicine characteristics of an average individual. dealing with the diagnostic and therapeutic These assumed characteristics are used in applications of radiant energy, including calculations assessing internal dose (also X-rays and radioisotopes. may be called "Standard Man").

RADIOLOGICAL ATTACK: The use of RELATIVE BIOLOGICAL EFFECT (RBE): radioactive or nuclear materials for A term relating the ability of radiations with malicious purposes, such as blackmail, different LET ranges to produce a specific murder, sabotage, or terrorism. biologic response; the comparison of a dose of test radiation to a dose of 250keV RADIONUCLIDE: A radioactive species of x-ray that produces the same biologic an atom characterized by the constitution of response. its nucleus. A radioactive nuclide. RELATIVE RISK (RR): The rate of disease RADIORESISTANCE: Relative resistance in an exposed population divided by the

28 GLOSSARY – Nagasaki University Center for Frontier Life Sciences rate of disease in an unexposed detriment due to that dose. Risk constraints population. correspond to dose constraints but refer to potential exposures. REM (RAD EQUIVALENT MAN): A special unit of dose equivalent, now replaced by RISK ESTIMATE: The increment of the the SI unit sievert. 1 rem = 0.01 Sv. incidence or mortality rate projected to occur in a specified exposed population per RISK: A chance of injury, loss, or detriment; unit dose for a specified exposure regime a measure of the deleterious effects that and expression period. may be expected as the result of an action or inaction. ROENTGEN (R): The outmoded unit of exposure that has been replaced by the Si RISK ASSESSMENT: The process by unit Coulombs per kilogram. One roentgen which the risks associated with an action or equals 2.58 x 10-4 Coulombs per kilogram inaction are identified and quantified. of air.

RISK COEFFICIENT: The increase in the (REM): annual incidence or mortality rate per unit The outmoded dose equivalent unit that is dose: (1) absolute risk coefficient is the numerically equal to the absorbed dose in increase of the incidence or mortality rate rads multiplied by the quality factor, the per unit dose; (2) relative risk coefficient is distribution factor and any other necessary the fractional increase above the baseline modifying factor. It has been replaced by incidence or mortality rate per unit dose. the SIEVERT(Sv). 100 rem = 1Sv

RISK CONSTRAINT: A prospective and SAFETY: The achievement of proper source-related restriction on the individual operating conditions, prevention of risk (in the sense of probability of detriment accidents, or mitigation of accident due to a potential exposure) from a source, consequences. which provides a basic level of protection for the individuals most at risk from a SCATTERING: Change of direction of source and serves as an upper bound on subatomic particles or photons as a result the individual risk in optimization of of atomic collisions. protection for that source. This risk is a function of the probability of an unintended SCATTERED RADIATION: Radiation that, event causing a dose, and the probability of during its passage through a substance,

29 GLOSSARY – Nagasaki University Center for Frontier Life Sciences has been changed in direction. It may also and daughter will decay at the same rate have been modified by a decrease in until the parent is essentially exhausted. energy. It is one form of secondary radiation. SECURITY: The prevention and detection of, and response to, theft, sabotage, SCINTILLATION COUNTER: An unauthorized access, illegal transfer, or instrument that detects and measures other malicious acts involving nuclear gamma radiation by counting the light material, other radioactive substances, or flashes (scintillations) induced by the their associated installations. radiation. SEMI-CONDUCTOR DETECTOR: SCINTILLATOR: Substance in which Detection device for ionized radiation. flashes of light are generated by impinging Advantage is taken of the effect of free ionizing radiation (fluorescence). charge carrier generation when Nal(Tl)-monocrystals are particularly semi-conductor material (germanium, suitable for the detection of gamma silicon) is irradiated. Semi-conductor radiation and anthracene or diphenyl counters are particularly suitable for oxazole dissolved in toluene is suitable for gamma radiation due to their beta radiation. ZnS(Ag) is a favourable high energy resolution ability. scintillator for detection of alpha radiation. SHIELD: Material used to prevent or SEALED SOURCE (SEALED reduce the passage of ionizing radiation. RADIOISOTOPES): Any special radioactive material or byproduct encased SI (SYSTEME INTERNATIONAL): in a capsule designed to prevent leakage or International System of scientific escape of the material. nomenclature.

SECULAR EQUILIBRIUM: A state of SIEVERT (Sv): The special name for the SI parent-daughter equilibrium which is unit of equivalent dose, effective dose, and achieved when the half-life of the parent is operational dose quantities. much longer than the half-life of the daughter. In this case, if the two are not SKIN DOSE: The dose equivalent at a separated, the daughter will eventually be depth of 0.07 mm in the body at the decaying at the same rate at which it is application point of the personal dosimeter. being produced. At this point, both parent

30 GLOSSARY – Nagasaki University Center for Frontier Life Sciences

SOMATIC EFFECT (SOMATIC INJURY): of dose without threshold (i.e. cancer). Radiation induced damage to cells other than germ cells. : A hand held radiation detection instrument. See also SOURCE TISSUE: Tissue (which may be a Geiger-Mueller Tube. body organ) containing a significant amount of a radionuclide following intake of SYNCHROTRON: Accelerator in which that radionuclide. particles travel on an orbit with a fixed radius. The acceleration is effected by SPECIFIC ACTIVITY: Total activity of a electric fields and guidance on the orbit by given nuclide per gram of a compound, magnetic fields. The larger the diameter of element, or radioactive nuclide. a synchrotron, the higher the particle energies which can be obtained. SPECIFIC ENERGY (z): The energy per unit mass actually deposited in a TARGET CELLS: Cells in a tissue that microscopic volume in a single energy have been determined to be the key cells in deposition event or at a given absorbed which changes occur in order to produce dose. This is a stochastic quantity as an end point such as cancer. opposed to its average, the absorbed dose, D. The mean energy imparted by ionizing TERATOGENIC EFFECT: Birth defects radiation to a medium per unit mass. that are not passed on to future generations, caused by exposure to a toxin STATISTICAL POWER: The probability as a fetus. that an epidemiological study will detect a given level of elevated risk with a specified TERRESTRIAL RADIATION: Radiation degree of confidence. emitted by naturally occurring radioactive materials, such as uranium (U), thorium STEM CELL: Non-differentiated, (Th), and radon (Rn) in the earth. pluripotent cell, capable of unlimited cell division. THERMOLUMINESCENT DOSIMETER (TLD): A small badge worn by workers, STOCHASTIC EFFECTS: Induced which is used to passively monitor personal pathological changes for which the radiation doses. Lithium fluoride crystals probability of an effect occurring, rather are the functional units in the badge. In than the severity, is regarded as a function which a small fraction of the energy

31 GLOSSARY – Nagasaki University Center for Frontier Life Sciences absorbed from ionizing radiation is stored in a metastable energy state. This energy is TRACK STRUCTURE: Spatial patterns of later recovered as visible photons, when energy deposition in matter along the track the material is heated. from the passage of ionizing radiation.

THRESHOLD DOSE (FOR TISSUE TRANSURANIC: Pertaining to elements REACTIONS): Dose estimated to result in with atomic numbers higher than uranium only 1% incidence of tissue reactions. (92). For example, plutonium (Pu) and americium (Am) are transuranics. TISSUE EQUIVALENT: Term from radiation protection measuring technology; UNCERTAINTY: The range of values tissue equivalent denotes a substance, with within which the true value is estimated to absorbing and scattering properties for a lie. It is a best estimate of possible given radiation that sufficiently match those inaccuracy due to both random and of a certain biological tissue. systemic errors.

TISSUE WEIGHTING FACTOR, wT: The UNSCEAR (UNITED NATIONS factor by which the equivalent dose in a SCIENTIFIC COMMITTEE ON THE tissue or organ T is weighted to represent EFFECTS OF ATOMIC RADIATION): A the relative contribution of that tissue or UN committee that publishes periodic organ to the total health detriment resulting reports on sources and effects of ionizing from uniform irradiation of the body (ICRP radiation. 1991b). It is weighted such that: URANIUM, DEPLETED: Uranium containing less than 0.7% uranium-235, the amount found in natural uranium. TRACER, ISOTOPIC: An isotope or mixture of isotopes of an element or URANIUM, ENRICHED: Uranium in which elements that which may be incorporated the proportion of the isotope uranium-235 into a sample to permit observation of the has been increased by removing course of that element, alone or in uranium-238 mechanically. combination, through a chemical, biological or physical process. The observation may URANIUM, NATURAL: Uranium as found be made by measurement of radioactivity in nature. It contains about 0.7 percent or of isotopic abundance. uranium-235, 99.3 percent uranium-238,

32 GLOSSARY – Nagasaki University Center for Frontier Life Sciences and a trace of uranium-234. . It typically uses heavy shielding to keep out background radiation from the VAN DE GRAAFF GENERATOR: A ultra-sensitive radiation detectors and Machine to generate very high direct electronic counting equipment. voltages used to accelerate charged particles to high energies (up to 12 MeV). X-RAY: Electromagnetic radiation By means of a non-conductive endless strip, originating from the orbital electrons of an electrical charges are transported to an atom, usually produced by bombarding a insulated hollow sphere which is thereby metallic target with fast electrons in a high charged to very high voltages. vacuum.

VOXEL PHANTOM: Computational WIPE SAMPLE: A sample made for the anthropomorphic phantom based on purpose of determining the presence of medical tomographic images where the removable radioactive contamination on a anatomy is described by small surface. It is done by wiping, with slight three-dimensional volume elements pressure, a piece of soft filter paper over a (voxels) specifying the density and the representative type of surface area. It is atomic composition of the various organs also known as a "swipe or smear" sample. and tissues of the human body. WIPE TEST: In addition to direct WEIGHTED DOSE (d): The dose to measurement, the wipe test is used to A-bomb survivors, roughly adjusted to determine radioactive contamination on the account for the increased effectiveness of surface of a solid body. In this easily the small neutron absorbed dose performed test, part of the contamination contribution. The weighted dose equals the adhering to the surface is wiped off e.g. gamma-ray absorbed dose to a specified with a paper fleece and can be measured. organ plus the neutron absorbed dose multiplied by a weighting factor that has Z: Atomic number of a given nuclide. usually been set equal to 10 in analyses by the Radiation Effects Research Foundation (RERF).

WHOLE BODY COUNTER: A device used to identify and measure the radioactive material in the body of human beings and

33 GLOSSARY – Nagasaki University Center for Frontier Life Sciences

BIBLIOGRAPHY Radionuclide Safety And Methodology, Reference Manual, University of British Columbia, Department of Health Safety and Environment, 2008.

The 2007 Recommendations of the ICRP, Publication 103, 2007.

Health Risks from Exposure to Low Levels of Ionizing Radiation: BEIR VII – Phase 2, 2006.

Dose-effect relationships and estimation of the carcinogenic effects of low doses of ionizing radiation. Académie des Sciences - Académie nationale de Médecine, 2005.

Glossary of Nuclear Science Terms. Lawrence Berkeley National Laboratory, http://www.lbl.gov/.

Glossary of Radiological Terms. Centers for Disease Control and Prevension, http://www.cdc.gov/.

Radiation Terms and Definitions. Society, http://hps.org/.

Glossary of Nuclear Terms. European Nuclear Society, http://www.euronuclear.org/ 2009 Nagasaki University Center for Frontier Life Sciences

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