ISO 12749-2:2022

INTERNATIONAL ISO
STANDARD 12749-2
Second edition
2022-08
Nuclear energy, nuclear technologies,
and radiological protection —
Vocabulary —
Part 2:
Radiological protection
Énergie nucléaire, technologies nucléaires et protection
radiologique — Vocabulaire —
Partie 2: Radioprotection
Reference number
© ISO 2022
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Published in Switzerland
ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
3.1 General terms related to radiological protection . 1
3.2 General terms related to biological effect . 6
3.3 Terms related to radiation exposure . 8
3.4 Terms related to measurement and radiological monitoring .13
3.5 Terms related to technical aspects. 25
3.6 Terms related to regulation . 27
3.7 Terms related to emergency .29
Annex A (informative) Methodology used in the development of the vocabulary .32
Bibliography .43
Index .46
iii
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
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electrotechnical standardization.
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different types of ISO documents should be noted. This document was drafted in accordance with the
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www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 85, Nuclear energy, nuclear technologies,
and radiological protection.
This second edition cancels and replaces the first edition (ISO 12749-2:2013), which has been technically
revised.
The main changes are as follows:
— Merging of the headings “Terms related to radiological monitoring” and “Terms related to
measurement”.
— Addition of the heading “Terms related to emergency”.
A list of all parts in the ISO 12749 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
iv
Introduction
This document will provide terms and definitions for general nuclear energy concepts dealing with
radiological protection and other related concepts. These concepts include protection for human health
and the environment; radiation measurement methods and instruments; and the prevision or direct
determination of the effect of ionizing radiation on the body.
Terminological data are taken from ISO standards developed and revised by ISO/TC 85/SC 2 and other
technically validated documents such as the IAEA Basic Safety Standards, ISO/IEC 80000-10, ICRP,
ICRU 51, ICRU 85a, VIM and BIPM.
Unambiguous communication of radiological protection concepts is crucial taking into account
the relevant implications that may arise from misunderstandings with regard to equipment and
materials involved in the standards dealing with this subject. The market of radiological protection
is a heterogeneous one because it comprises equipment designed, built and operated along the safe
practices defined by the radiological protection specialists. This market also includes nuclear reactors,
nuclear fuel cycle, cosmic radiation, scientific research industrial applications, nuclear medicine
and radiotherapy, and instruments to monitor both personnel and facilities and sites. In view of the
foregoing, and the large number of people involved who have different levels of scientific and technical
knowledge, there can be widely divergent understandings and assumptions about concepts. The results
are poor communication, high risk of accidents and duplication of effort as different groups are going to
define concepts according to their perspectives.
Conceptual arrangement of terms and definitions is based on concepts systems that show corresponding
relationships among radiological protection concepts. In Annex A there is a detailed explanation
of this subject. Such arrangement provides users with a structured view of this special sub domain
within the nuclear energy sector and will facilitate common understanding of radiological protection
concepts. Besides, concepts systems and conceptual arrangement of terminological data will be helpful
to any kind of user because it will promote clear, accurate and useful communication. At the end of this
document an alphabetical index shows the terms followed by their corresponding notation.
v
INTERNATIONAL STANDARD ISO 12749-2:2022(E)
Nuclear energy, nuclear technologies, and radiological
protection — Vocabulary —
Part 2:
Radiological protection
1 Scope
This document defines terms and definitions related to radiological protection concepts in the subject
field of nuclear energy, nuclear technology and the different nuclear applications. It is intended to
facilitate communication and promote common understanding.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1 General terms related to radiological protection
3.1.1
radiological protection
radiation protection
protection of people and the environment from the harmful effects of exposure to ionizing radiation
and the means for achieving such protection while allowing its beneficial uses
[SOURCE: IAEA. IAEA safety glossary: 2018 edition. Vienna: IAEA, 2019. p. 278, modified — “and the
environment” and “while allowing its beneficial uses” was added and the demonstrative pronoun “that”
was replaced with “such protection”.]
Note 1 to entry: People include workers, patients and members of the public.
Note 2 to entry: Environment includes biota, waters, lands, and air.
3.1.2
radiation source
source
apparatus, substance or installation, that can cause radiation exposure (3.3.1), by emitting ionizing
radiation or releasing radioactive substances or materials
3.1.3
radioactivity
stochastic process whereby nuclei undergo spontaneous random disintegration, usually accompanied
by the emission of subatomic particles, or photons
[SOURCE: ISO 12749-1:2020, 3.1.1, modified — “random” was added in the definition.]
3.1.4
radioactive material
material designated in national law or by a regulatory body as being subject to regulatory control
because of its radioactivity (3.1.3)
Note 1 to entry: This is the ‘regulatory’ meaning of radioactive, and should not be confused with the ‘scientific’
meaning of radioactive.
Note 2 to entry: The term radioactive substance is also used to indicate that the ‘scientific’ meaning of radioactive
is intended, rather than the ‘regulatory” meaning of radioactive suggested by the term radioactive material.
[SOURCE: IAEA. IAEA safety glossary: 2018 edition. Vienna: IAEA, 2019. p. 278]
Note 3 to entry: Whenever the term "radioactive substance" is mentioned in any definition or note to entry
throughout this document, it covers the concept defined in 3.1.4.
3.1.5
radioactive contamination
contamination
radioactive substances on surfaces, or within solids, liquids or gases (including the human body), where
their presence is unintended or undesirable, or the process giving rise to their presence in such places
[SOURCE: IAEA. IAEA safety glossary: 2018 edition. Vienna: IAEA, 2019. p. 278, modified — The
parenthesis was deleted and replaced with commas.]
3.1.6
airborne radioactive substance
radioactive substance dispersed in the air in the form of dusts, fumes, particulates, mists, vapours, or
gases
[SOURCE: ISO 16639:2017, 3.4]
3.1.7
derived air concentration
DAC
derived limit (3.1.15) on the activity concentration in air of a specified radionuclide, calculated such
that the reference individual, breathing air with constant contamination at the DAC with the breathing
behavior of a reference worker for a working year, would receive an intake (3.3.4) corresponding to the
annual intake for the radionuclide in question
Note 1 to entry: The parameter values recommended by the International Commission on Radiological Protection
for calculating DACs are a breathing rate of 1,2 m /h and a working year of 2 000 h.
[SOURCE: IAEA. IAEA safety glossary: 2018 edition. Vienna: IAEA, 2019. p. 278]
3.1.8
air contamination area
area accessible to individuals where the measured or calculated radioactivity (3.1.3) concentrations of
an airborne radioactive substance (3.1.6) exceeds or is likely to exceed the applicable criteria
[SOURCE: ISO 16639:2017, 3.5, modified — Addition of “or calculated”, “activity” was changed to
“radioactivity” and deletion of “national” from “to exceed the applicable national criteria”.]
3.1.9
decontamination
complete or partial removal of radioactive contamination (3.1.5) by a deliberate physical, chemical or
biological process
Note 1 to entry: It is preferred that radioactive decontamination does not significantly change the characteristics
of the surface.
[SOURCE: IAEA. IAEA safety glossary: 2018 edition. Vienna: IAEA, 2019. p. 278, modified — “the” was
deleted from the definition and “radioactive” was added in the definition and the Note 1 to entry.]
3.1.10
justification
process of determining for an emergency exposure situation (3.3.26) or an existing exposure situation
(3.3.27) whether a proposed protective action or remedial action is likely to be beneficial, whether the
expected benefits to individuals and to society from introducing or continuing the protective action or
remedial action outweigh the cost of such action and any harm or damage caused by the action
[SOURCE: IAEA. IAEA safety glossary: 2018 edition. Vienna: IAEA, 2019. p. 278, modified — “overall”
and “including the reduction in radiation detriment” were deleted.]
3.1.11
optimization (of protection and safety)
process of determining what level of protection and safety would result in the magnitude of individual
doses, the number of individuals, workers and members of the public, subject to exposure and the
likelihood of exposure being as low as reasonably achievable, economic and social factors being taken
into account (ALARA)
[SOURCE: IAEA. IAEA safety glossary: 2018 edition. Vienna: IAEA, 2019. p. 278]
Note 1 to entry: For medical exposures (3.3.29) of patients, the optimization of protection and safety is the
management of the radiation dose to the patient commensurate with the medical purpose.
3.1.12
dose limit
value of the effective dose (3.1.24) or the equivalent dose (3.1.22) to individuals from planned exposure
situations (3.3.21), or doses (3.1.16) to biota, that shall not be exceeded
[SOURCE: 2007 Recommendations of the International Commission on Radiological Protection.
ICRP Publication 103. Ann. ICRP 37 (2-4)]
3.1.13
dose constraint
prospective and source related value of individual dose (3.1.16) that is used in planned exposure
situations (3.3.21) as a parameter for the optimization of protection and safety (3.1.11) for the source,
and that serves as a boundary in defining the range of options in optimization
[SOURCE: IAEA. IAEA safety glossary: 2018 edition. Vienna: IAEA, 2019. p. 278]
3.1.14
annual limit on intake
ALI
intake (3.3.4) by inhalation or ingestion or through the skin of a given radionuclide in a year by reference
individual which would result in a committed dose (3.1.17) equal to the relevant dose limit (3.1.12)
Note 1 to entry: The annual limit on intake is expressed in units of activity.
[SOURCE: IAEA. IAEA safety glossary: 2018 edition. Vienna: IAEA, 2019. p. 278]
3.1.15
derived limit
limit on a measurable quantity set, on the basis of a model, such that compliance with the derived limit
may be assumed to ensure compliance with a primary limit
[SOURCE: IAEA. IAEA safety glossary: 2018 edition. Vienna: IAEA, 2019. p. 278]
3.1.16
dose
measure of the energy deposited by radiation in a target
[SOURCE: IAEA. IAEA safety glossary, 2018 Edition. Vienna: IAEA, 2019. p. 278]
Note 1 to entry: When unspecified, dose refers to quantity of absorbed dose (3.1.20), measured in gray (1 Gy = 1 J/
kg).
Note 2 to entry: Depending upon the context in which it is used, the generic term dose may also refer to equivalent
dose (3.1.22), effective dose (3.1.24) or other dose-related quantities.
[SOURCE: ISO 12749-1:2020, 3.3.6]
3.1.17
committed dose
lifetime dose (3.1.16) expected to result from an intake (3.3.4)
[SOURCE: IAEA. Radiation protection and safety of radiation sources: international basic safety
Standards. IAEA Safety Standards Series No, GSR Part 3. Vienna: IAEA, 2014. p. 471]
Note 1 to entry: For radiological protection (3.1.1) calculational purposes, lifetime is typically taken to be 50 years
for adults and the time to the age of 70 years for intakes by children. (That is, for intakes by children, 70 years
minus the age in years: so, for example 60 years for 10 years old child).
3.1.18
committed equivalent dose
H (τ)
T
quantity H (τ), defined as:
T
t +τ
HH()τ = ()t dt
TT
∫
t
where t is the time of intake (3.3.4), H (t) is the equivalent dose (3.1.22) rate at time t in tissue or organ
0 T
T and τ is the integration time elapsed after an intake of radioactive substances
Note 1 to entry: Where τ is not specified, it is taken to be 50 years for adults and the time to the age of 70 years
for intakes by children. (That is, for intakes by children, 70 years minus the age in years: so, for example 60 years
for a 10 years old child).
[SOURCE: IAEA. IAEA safety glossary: 2018 edition. Vienna: IAEA, 2019. p. 278]
3.1.19
committed effective dose
E(τ)
quantity E(τ), defined as:
Ew()ττ= T ()
∑ T T
T
where H (τ) is the committed equivalent dose (3.1.18) to tissue or organ T over the integration time τ
T
elapsed after an intake (3.3.4) of radioactive substances and w is the tissue weighting factor (3.1.23) for
T
tissue or organ T.
Note 1 to entry: Where τ is not specified, it will be taken to be 50 years for adults and the time to the age of
70 years for intakes by children.
[SOURCE: IAEA. IAEA safety glossary: 2018 edition. Vienna: IAEA, 2019. p. 278]
3.1.20
absorbed dose
D
differential quotient of ε with respect to m, where ε is the mean energy imparted by ionizing radiation
to matter of mass m:
dε
D=
dm
[SOURCE: ISO 80000-10:2019, 10.81.1]
Note 1 to entry: The gray is a special name for joule J/kg and is to be used as the coherent SI unit for absorbed
dose.
3.1.21
radiation weighting factor
w
R
dimensionless factor by which the organ or tissue absorbed dose (3.1.20) is multiplied to reflect the
higher biological effectiveness of high-LET (3.1.25) radiations compared with low-LET radiations. It is
used to derive the equivalent dose (3.1.22) from the absorbed dose averaged over a tissue or organ
Note 1 to entry: The radiation weighting factor is used to derive the equivalent dose from the absorbed dose
averaged over a tissue or organ.
[SOURCE: 2007 Recommendations of the International Commission on Radiological Protection.
ICRP Publication 103. Ann. ICRP 37 (2-4) modified — The definition was split into a definition and a
Note to entry.]
3.1.22
equivalent dose
quantity H defined as: Hw= D where D is the absorbed dose (3.1.20) delivered by
TR, TR,,RT R TR,
radiation type R averaged over a tissue or organ T and w is the radiation weighting factor (3.1.21) for
R
radiation type R
Note 1 to entry: When the radiation field is composed of different radiation types with different values of w the
R
equivalent dose is:
Hw= D
∑
TR T,R
R
Note 2 to entry: The unit of equivalent dose is J/kg and its special name is sievert (Sv).
[SOURCE: IAEA. IAEA safety glossary: 2018 edition. Vienna: IAEA, 2019. p. 278. modified — The
definition was split into a definition and two Notes to entry.]
3.1.23
tissue weighting factor
w
T
multiplier of the equivalent dose (3.1.22) to an organ or tissue used for radiological protection (3.1.1)
purposes to account for the different sensitivities of different organs or tissues to the induction of
stochastic effects (3.2.5) of radiation
[SOURCE: IAEA. IAEA safety glossary: 2018 edition. Vienna: IAEA, 2019. p. 278]
3.1.24
effective dose
E
tissue-weighted sum of the equivalent doses (3.1.22) in all specified tissues and organs of the body, given
by the expression:
ED=oww r=EHw
∑∑ ∑
T RT,R T T
T R T
where H or w D is the equivalent dose in a tissue or organ, T, and w is the tissue weighting factor
T R T,R T
(3.1.23)
Note 1 to entry: The unit for the effective dose is J/kg, and its special name is sievert (Sv).
Note 2 to entry: In order to evaluate the effective dose different anthropomorphic reference models are used;
they can be adapted to sex and age.
[SOURCE: 2007 Recommendations of the International Commission on Radiological Protection.
ICRP Publication 103. Ann. ICRP 37 (2-4)]
3.1.25
linear energy transfer
LET
quotient of the mean energy, dE , lost by the charged particles due to electronic interactions in
Δ
traversing a distance, dl, minus the mean sum of the kinetic energies in excess of Δ of all the electrons
released by charged particles and dl:
dE
Δ
L =
Δ
dl
[SOURCE: ISO 80000-10:2019, 10.85]
3.1.26
relative biological effectiveness
RBE
ratio of a dose of a low-LET (3.1.25) reference radiation to a dose of the radiation considered that gives
an identical biological effect (3.2.1)
[SOURCE: 2007 Recommendations of the International Commission on Radiological Protection.
ICRP Publication 103. Ann. ICRP 37 (2-4)]
Note 1 to entry: The most used reference radiation is 250 keV x-rays.
3.2 General terms related to biological effect
3.2.1
biological effect
effect of ionizing radiation in living cells
EXAMPLE Erythema, damage to the haemopoietic system, and acute radiation syndrome.
[SOURCE: IAEA. IAEA safety glossary: 2018 edition. Vienna: IAEA, 2019. p. 278]
3.2.2
deterministic effect
tissue reaction
radiation induced health effect for which generally a threshold level of dose (3.1.16) exists above which
the severity of the effect is greater for a higher dose
[SOURCE: IAEA. IAEA safety glossary: 2018 edition. Vienna: IAEA, 2019. p. 278]
3.2.3
acute radiation syndrome
acute radiation sickness
ARS
acute illness caused by irradiation of the entire body (or most of the body) by a high dose (3.1.16) of
penetrating radiation in a very short period of time (usually a matter of minutes)
Note 1 to entry: The required conditions for Acute Radiation Syndrome (ARS) are:
— The radiation dose is large (i.e., greater than 0,7 Gy).
— The dose is usually from an external exposure.
— The radiation is penetrating.
— The entire body (or a significant portion of it) has received the dose.
[SOURCE: Brochure for Physicians, Acute Radiation Syndrome, Centers for Disease Control and
Prevention, https:// www .cdc .gov/ nceh/ radiation/ emergencies/ pdf/ ars .pdf]
Note 2 to entry: With the assumption of the linear-non-threshold dose response for stochastic radiation effects
(LNT model (3.2.8)) in the low dose range (< 100 mSv) and, under the conditions of the described concept of
calculation, effective dose (3.1.24) is an additive quantity. At higher radiation doses, when tissue reactions
(deterministic effects (3.2.2)) can occur, the absorbed doses (3.1.20) in organs and tissues have to be used for risk
evaluation.
[SOURCE: 2007 Recommendations of the International Commission on Radiological Protection.
ICRP Publication 103. Ann. ICRP 37 (2-4)]
3.2.4
threshold dose
dose estimated to result in only 1 % incidence of tissue reactions
[SOURCE: 2007 Recommendations of the International Commission on Radiological Protection.
ICRP Publication 103. Ann. ICRP 37 (2-4)]
3.2.5
stochastic effect
radiation induced health effect, whose probability of occurrence is greater for a higher radiation dose
(3.1.16) and which severity, if it occurs, is independent of dose
Note 1 to entry: Stochastic effects may be somatic effects (3.2.9) or hereditary effects (3.2.10), and generally occur
without a threshold level of dose. Examples include solid cancers and haematologic cancers (leukaemia and
lymphoma).
[SOURCE: IAEA. IAEA safety glossary: 2018 edition. Vienna: IAEA, 2019. p. 278, modified — “the
probability of occurrence of which” was replaced with “whose probability of occurrence” and ”leukemia”
was replaced with “haematologic cancers”.]
3.2.6
risk coefficient
lifetime risk or radiation detriment (3.2.7) assumed to result from exposure to unit equivalent dose
(3.1.22) or effective dose (3.1.24)
[SOURCE: IAEA. IAEA safety glossary: 2018 edition. Vienna: IAEA, 2019. p. 278]
3.2.7
radiation detriment
total harm that would eventually be incurred by a group that is subject to exposure and by its
descendants as a result of the group’s exposure to radiation from a source
[SOURCE: IAEA. IAEA safety glossary: 2018 edition. Vienna: IAEA, 2019. p.278]
3.2.8
linear-non-threshold model
LNT model
dose-response model, which is based on the assumption that, in the low dose range, radiation doses
(3.1.16) greater than zero will increase the risk of excess cancer and/or heritable disease in a simple
proportionate manner
[SOURCE: 2007 Recommendations of the International Commission on Radiological Protection.
ICRP Publication 103. Ann. ICRP 37 (2-4)]
Note 1 to entry: Low doses (below about 100 mSv) and low dose rates.
3.2.9
somatic effect
radiation induced health effect that occurs in the exposed individual
Note 1 to entry: Somatic effect includes effects occurring after birth that are attributable to exposure in uterus.
Note 2 to entry: Deterministic effects (3.2.2) are normally also somatic effects.
[SOURCE: IAEA. IAEA safety glossary: 2018 edition. Vienna: IAEA, 2019. p. 278, modified — The note
was split in two and “stochastic effects may be somatic effects or hereditary effects” was deleted in the
second one.]
3.2.10
hereditary effect
radiation induced health effect that occurs in a descendant of the exposed individual
Note 1 to entry: The less precise term ‘genetic effect’ is also used, but hereditary effect is preferred.
Note 2 to entry: Hereditary effects are usually stochastic effects (3.2.5).
[SOURCE: IAEA. IAEA safety glossary: 2018 edition. Vienna: IAEA, 2019. p. 278]
3.3 Terms related to radiation exposure
3.3.1
radiation exposure
state or condition of being subject to ionizing radiation
Note 1 to entry: Exposure to ionizing radiation can be broadly divided into categories of exposure according to
the status of the individual.
[SOURCE: IAEA. IAEA safety glossary: 2018 edition. Vienna: IAEA, 2019. p. 278, modified — “irradiation”
was replaced with “ionizing radiation”.]
3.3.2
internal exposure
exposure to radiation from a source within the body
[SOURCE: IAEA. IAEA safety glossary: 2018 edition. Vienna: IAEA, 2019. p. 278]
3.3.3
specific absorbed fraction
SAF
fraction of energy of that emitted as a specified radiation type in a source region, S, that is absorbed per
unit mass of a target tissue, T
[SOURCE: 2007 Recommendations of the International Commission on Radiological Protection.
ICRP Publication 103. Ann. ICRP 37 (2-4) modified — “that is absorbed in 1 kg” was replaced with “that
is absorbed per unit mass”.]
3.3.4
intake
act or process of taking radionuclides into the body by inhalation or ingestion or through the skin
[SOURCE: IAEA. IAEA safety glossary: 2018 edition. Vienna: IAEA, 2019. p. 278 modified — The phrase
“by the operator” was deleted.]
EXAMPLE Intake by injection of a radiopharmaceutical, via a wound, or any other possible exposure
pathway.
3.3.5
absorption
transfer of material to blood regardless of mechanism, generally applied to dissociation of particles and
uptake into blood of soluble substances and material dissociated from particles
[SOURCE: ISO 16638-1:2015, 3.1, modified — “movement” was changed to “transfer”, “which generally”
with “generally” and “the uptake” with “uptake”.]
3.3.6
human alimentary tract model
HATM
biokinetic model for describing the movement of ingested materials through the human alimentary
tract
[SOURCE: ICRP, 2015. Occupational Intakes of Radionuclides: Part 1. ICRP Publication 130. Ann. ICRP 44
(2), modified by that published in publication 100 (ICRP, 2006)]
3.3.7
human respiratory tract model
HRTM
biokinetic model for describing the deposition, translocation, and absorption (3.3.5) of inhaled materials
in the human respiratory tract
[SOURCE: ICRP, 2015. Occupational Intakes of Radionuclides: Part 1. ICRP Publication 130. Ann. ICRP 44
(2), modified — The definition was split into a definition and a Note to entry. modified by that published
in publication 66 (ICRP, 1994a) and updated in this report.]
3.3.8
reference bioassay function
set of tabulated values m(t) predicted by a reference biokinetic model describing the time course of the
activity in the body following an acute intake (3.3.4), at time t
Note 1 to entry: A retention function m(t) represents the predicted activity of a radionuclide in the body, organ,
or tissue at a time t after the intake.
3.3.9
retention fraction
ratio of the activity measured in the body, or in excreta, to the intake (3.3.4)
[SOURCE: NCRP Composite glossary. Bethesda: NCRP, 2011. p. 217]
3.3.10
excretion function
set of tabulated values m(t) predicted by a reference biokinetic model describing the time course of the
activity excreted in body fluids or waste, e.g., urine or faeces, following an acute intake (3.3.4) at time t
Note 1 to entry: An excretion function m(t) represents the predicted activity of a radionuclide in a 24 h excreta
sample at a time t after the intake.
[SOURCE: ICRP, 2015. Occupational Intakes of Radionuclides: Part 1. ICRP Publication 130. Ann. ICRP 44
(2), modified — The definition was split into a definition and a Note to entry.]
3.3.11
excretion fraction
fraction of an intake (3.3.4) excreted per unit of time after a given time has elapsed since the intake
occurred
[SOURCE: ICRP. 1994. Dose coefficient for intake of radionuclides by workers. ICRP. Publication 68, Ann.
ICRP 24 (1-3)]
3.3.12
biological clearance
net effect (3.4.36) of the biological processes by which radionuclides are removed from the body or from
a tissue, organ or region of the body
[SOURCE: IAEA. IAEA safety glossary: 2018 edition. Vienna: IAEA, 2019. p. 278, modified — “clearance”
was replaced with “biological clearance”, “from a tissue, organ or area of the body” with “from the body
or from a tissue, organ or region of the body” in the definition.]
Note 1 to entry: The rate of biological clearance is the rate at which these biological processes occur.
3.3.13
total dose
dose from external exposure (3.3.14) in a given period plus the committed dose (3.1.17) from intakes
(3.3.4) of radionuclides in that same period
EXAMPLE Annual dose.
[SOURCE: IAEA. Radiation protection and safety of radiation sources: international basic safety
Standards. IAEA Safety Standards Series No. GSR Part 3. Vienna: IAEA, 2014. p. 471]
3.3.14
external exposure
exposure to radiation from a source outside the body
[SOURCE: IAEA. IAEA safety glossary: 2018 edition. Vienna: IAEA, 2019. p. 278]
3.3.15
partial-body dose
equivalent dose (3.1.22) to specified tissue, organs or parts of the body
Note 1 to entry: Identified by the name of the part of the particular tissue, organ or body, e.g. bone marrow dose,
skin dose, hand dose or dose to the lens of the eyes.
3.3.16
kerma
K
for uncharged ionizing radiation, the differential quotient of E with respect to m, where E is the
tr tr
mean sum of the initial kinetic energies of all the charged ionizing particles liberated in a mass m of a
material:
dE
tr
K=
dm
[SOURCE: ISO 80000-10:2019, 86.1]
Note 1 to entry: It is expressed as K = dE /dm
tr
Note 2 to entry: The unit is J/kg. The special name for the unit of kerma is gray (Gy).
3.3.17
back-scatter factor
ratio of air kerma (3.3.16) in front of a phantom (3.4.71) to the air kerma at the same position free-in-air
without the phantom
Note 1 to entry: Radiation field is considered to be unidirectional with a direction of incidence perpendicular to
the phantom surface
[SOURCE: ISO 4037-3:2019, 3.1, modified — The definition was split into a definition and a Note to
entry.]
3.3.18
conversion coefficient
protection or operational quantities are calculated from physical quantities describing the radiation
field by multiplication with a conversion coefficient
Note 1 to entry: This term is used in external exposure (3.3.14) situations, while in internal dosimetry the ratios
of dose quantities and activity quantities are called dose coefficients (3.3.19).
[SOURCE: ICRU Report 95. 2020. Operational quantities for external radiation exposure. Journal of the
ICRU 20 (1). Bethesda: ICRU, 2020]
3.3.19
dose coefficient
dose (3.1.16) per unit intake (3.3.4) of a radioactive substance
Note 1 to entry: Sometimes it is also used to describe other coefficients linking quantities or concentrations
of activity to doses or dose rates, such as the external dose rate at a specified distance above a surface with a
deposit of a specified activity per unit area of a specified radionuclide.
[SOURCE: 2007 Recommendations of the International Commission on Radiological Protection.
ICRP Publication 103. Ann. ICRP 37 (2-4), modified — The wording was split into a definition and a
Note to entry.]
3.3.20
exposure situation
circumstances of the exposure of the individual(s) or the environment to ionizing radiation sources
(3.1.2)
[SOURCE: IAEA. IAEA safety glossary: 2018 edition. Vienna: IAEA, 2019. p. 278, modified — “or the
environment” was added and “undergoing exposure” was replaced with “ionizing radiation sources”.]
3.3.21
planned exposure situation
situation of "https:// kos .iaea .org/ iaea -safety -glossary/ 1158" \h exposure that arises from the planned
operation of a source or from a planned activity that results in an exposure due to a source.
[SOURCE: IAEA. IAEA safety glossary: 2018 edition. Vienna: IAEA, 2019. p. 278]
3.3.22
discharge
planned and controlled release of (gaseous or liquid) radioactive material (3.1.4) to the environment
[SOURCE: ISO 18417:2017, 3.2, modified — “gas” was replaced with “gaseous”.]
3.3.23
occupancy factor
typical fraction of the time for which a location is occupied by an individual or group.
[SOURCE: IAEA. IAEA safety glossary: 2018 edition. Vienna: IAEA, 2019. p. 278]
3.3.24
potential exposure
exposure that is not expected to be delivered with certainty but that may result from an accident at a
source or an event (3.3.25) or sequence of events of a probabilistic nature, including equipment failures
and operating errors
[SOURCE: 2007 Recommendations of the International Commission on Radiological Protection.
ICRP Publication 103. Ann. ICRP 37 (2-4)]
3.3.25
event
any unintended occurrence, including operating error, equipment failure or other mishap, and
deliberate action on the part of others, the consequences or potential consequences of which are not
negligible from the point of view of protection and safety
[SOURCE: IAEA. IAEA safety glossary: 2018 edition. Vienna: IAEA, 2019. p. 278, modified — The phrase
“by the operator” was deleted.]
3.3.26
emergency exposure situation
situation of exposure that arises as a result of an accident, a malicious act or other unexpected event
(3.3.25), and requires prompt action in order to avoid or to reduce adverse consequences
Note 1 to entry: Exposure in an emergency can include both occupational exposure and public exposure, and can
include unplanned exposures resulting directly in the emergency exposure situation and planned exposures to
emergency workers (3.7.11) and helpers in an emergency undertaking actions to mitigate the consequences of the
emergency.
Note 2 to entry: Exposure in an emergency (3.7.1) can be reduced only by protective actions and other response
actions.
[SOURCE: IAEA. IAEA safety glossary: 2018 edition. Vienna: IAEA, 2019. p. 278]
3.3.27
existing exposure situation
situation of exposure that already exists when a decision on the need for control needs to be taken
Note 1 to entry: Existing exposure situations include exposure to natural background radiation that is amenable
to control; exposure due to residual radioactive material (3.1.4) that derives from past practices that were never
subject to regulatory control; and exposure due to residual radioactive material deriving from a nuclear or
radiological emergency (3.7.1) after an emergency exposure situation (3.3.26) has been declared ended.
[SOURCE: IAEA. IAEA safety glossary: 2018 edition. Vienna: IAEA, 2019. p. 278]
3.3.28
reference level
level of dose (3.1.16), risk or activity concentration, for an emergency exposure situation (3.3.26) or
an existing exposure situation (3.3.27), above which it is not appropriate to plan to allow exposures to
occur and below which optimization of protection and safety (3.1.11) would continue to be implemented
Note 1 to entry: The value chosen for a reference level will depend upon the prevailing circumstances for the
exposure under consideration.
[SOURCE: IAEA. IAEA safety glossary: 2018 edition. Vienna: IAEA, 2019. p. 278, modified — The
sentence syntactics was changed.]
3.3.29
medical exposure
exposure incurred by patients for the purposes of their own medical or dental diagnosis (diagnostic
exposure) or medical treatment (therapeutic exposure); by caregivers and comforters; and by
volunteers subject to exposure as part of a programme of biomedical research
[SOURCE: IAEA. IAEA safety glossary: 2018 edition. Vienna: IAEA, 2019. p. 278]
3.3.30
diagnostic reference level
DRL
level used in medical imaging to indicate whether, in routine conditions, the dose (3.1.16) to the patient
or the amount of radiopharmaceuticals administered in a specified radiological procedure is unusually
high or unusually low for that procedure
[SOURCE: IAEA. Radiation protection and safety of radiation sources: international basic safety
Standards. IAEA Safety Standards Series No. GSR Part 3. Vienna: IAEA, 2014. p. 471]
Note 1 to entry: In the case of radio pharmaceuticals, DRL is level of activity for typical examination for a group
of standardized patients or standard phantom (3.4.71) for broadly defined types of equipment.
Note 2 to entry: These levels are indicative of good practice when not exceeded, for standard procedures when
good and normal practice regarding diagnostic and technical performance is applied.
[SOURCE: IAEA. Optimization of the radiological protection of patients undergoing radiography,
fluoroscopy and computed tomography. IAEA TECDOC 1423. Vienna: IAEA, 2004. p. 121, modified — “a
radio pharmaceuticals” was replaced with “radio pharmaceuticals”.]
3.3.31
occupational exposure
exposure of workers incurred in the course of their work
[SOURCE: IAEA. Radiation protection and safety of radiation sources: international basic safety
Standards. IAEA Safety Standards Series No, GSR Part 3. Vienna: IAEA, 2014. p. 471]
3.3.32
public exposure
exposure incurred by members of the public from radiation sources (3.1.2), excluding any occupational
or medical exposure (3.3.29)
[SOURCE: 2007 Recommendations of the International Commission on Radiological Protection.
ICRP Publication 103. Ann. ICRP 37 (2-4), modified — “and the normal local natural background
radiations” was deleted.]
3.4 Terms related to measurement and radiological monitoring
3.4.1
measurement
process of experimentally obtaining one or more quantity values that can reasonably be attributed to a
quantity
[SOURCE: ISO 12749-1:2020, 3.4.1]
3.4.2
biological dosimetry
assessment of the absorbed dose (3.1.20) of ionizing radiation using indicators found in biological
material, particularly peripheral blood
[SOURCE: ISO 21243:2008, 3.4, modified — “particularly peripheral blood” was added.]
3.4.3
chromosome aberration
change in the normal structure of a chromosome involving both chromatids of a single chromosome at
the same locus as observed in metaphase
[SOURCE: ISO 20046:2019, 3.10]
3.4.4
unstable chromosome aberration
chromosomal aberration which is lethal to the cell
EXAMPLE Dicentrics/centric rings/acentric fragments.
3.4.5
stable chromosome aberration
chromosomal aberration which is not lethal to the cell and can be passed on to daughter cells (e.g.
simple translocation)
EXAMPLE Translocations/insertions/inversions.
3.4.6
radiobioassay
bioassay
procedure used to determine the nature, activity, location, or retention of radionuclides in the body
by in vivo measurement (3.4.8) or by in vitro measurement (3.4.7) of material excreted or otherwise
removed from the body
[SOURCE: IAEA. IAEA safety glossary: 2018 edition. Vienna: IAEA, 2019. p. 278]
3.4.7
in vitro measurement
measurements (3.4.1) to determine the presence of, or to estimate the amount of, radioactive material
(3.1.4) in the excreta or in other biological materials removed from the body
[SOURCE: ISO 28218:2010, 3.14, modified — “in vitro radiobioassay” was replaced with “in vitro
measurement”.]
3.4.8
in vivo measurement
direct measurements
measurement (3.4.1) to determine the presence of or to estimate the amount of radioactive material
(3.1.4) in a living organism
Note 1 to entry: Normally, the measurement devices are whole-body or partial-body (e.g. lung, thyroid) counters.
3.4.9
whole-body counter
WBC
equipment for the determination of the presence, location, and/or amount of radioactivity (3.1.3) in the
body
3.4.10
lung counter
equipment for the determination of the presence, location, and/or amount of radioactive materials
(3.1.4) taken up by the lung(s)
3.4.11
thyroid counter
equipment for the determination of the presence, location, and/or amount of radioactive materials
(3.1.4) taken up by the thyroid
3.4.12
dosemeter
dosimeter
device having a reproducible, measurable response to radiation that can be used to measure absorbed
dose (3.1.20) or personal dose equivalent (3.4.76)
3.4.13
irradiated dose
H
ref
conventional quantity value (3.4.26) of the dose (3.1.16) to which the dosemeter (3.4.12) is irradiated
[SOURCE: ISO 14146:2018, 3.10]
3.4.14
passive integrating dosemeter
dosemeter (3.4.12) that utilizes one or more detectors (3.4.39) to integrate information about the
absorbed energy and needs a readout unit to display the information
[SOURCE: ISO 15690:2013, 3.2.2, modified — “personal”
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