ICRP Glossary

The ICRP Glossary collects ICRP’s definitive explanations of terms for current use. Some entries include historical descriptions to help readers better understand the term in a particular context.

It is a living document, updated regularly.

Many ICRP publications feature their own glossaries including, for example, highly specialized terms relevant to that specific publication or helpful for a reader to have close at hand, or when introducing new terms to be added to the ICRP Glossary.

Although the ICRP Glossary is not a dictionary, terms already well covered in the Oxford English Dictionary are not included here unless further explanation is needed to understand the way in which these terms are used in ICRP publications.

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A

B

C

D

E

F

G

H

I

J

K

L

M

N

O

P

Q

R

S

T

U

V

W

X

Y

Z

...

0-9

• 4DCT (see Time-resolved computed tomography)

A

• Absolute risk

• Absorbed dose, D

• Absorbed fraction

• Absorption

• Accelerated fractionation

• Acceptance test

• Access control

• Accountability

• Accreditation

• Action Level

• Activation

• Active detection system

• Active (red) bone marrow

• Activity

• Activity median thermodynamic diameter

• Acute exposure

• Acute radiation sickness (see Acute radiation syndrome)

• Acute radiation syndrome

• Additional dose

• Adaptive response

• Additive risk projection model

• Adenoma

• Adventitious

• Adventitious source

• Aerodynamic diameter

• Air-kerma rate constant

• Air kerma at the patient entrance reference point

• Air-kerma, entrance surface

• Air-kerma, incident

• Air-kerma, product

• ALARA

• ALI (see Annual limit on intake)

• Alimentary tract

• Alimentary tract transfer factor

• Allometry

• Alpha decay

• Alveolar-interstitial region

• AMAD (see Activity median aerodynamic diameter)

• Ambient dose equivalent, H*(10)

• AML/eto

• Angiogenesis

• Annihilation photons

• Annual dose

• Annual intake

• Annual limit on intake

• Apoptosis

• Area monitoring

• ARS (see Acute radiation syndrome)

• Attributable risk

• Auger transition

• Authorised discharge

• Authorization

• Authorized limit

• Autoimmune disease

• Automatic exposure control

• Autonomy

• Averted dose

B

• Background dose (rate)

• Backscatter detection system

• Backscatter factor

• Basal cell

• Baseline disease rates

• BAT (see Best available techniques)

• Bcr/abl (see Breakpoint cluster region/abelson)

• Beneficence

• Benthic

• Best available techniques

• Beta-minus decay

• Beta-plus decay

• Bioassay

• Biological half-life

• Biomarker

• Biomedical research volunteer

• Bioturbation

• Bone marrow

• Bradycardia

• Brachytherapy

• Branching fraction

• Bragg peak

• Breakpoint cluster region/abelson

• Broad beam therapy irradiation technique

• Bronchial region

• Bronchiolar region

• Bystander effect

C

• CACA (see Cobblestone area forming cell assay)

• CAFC (see Cobblestone area forming cell assay)

• CBCT (see Cone beam computed tomography)

• Cardiac arrhythmias

• Cardiac valve diseases

• Cardiomyopathy

• Cardioverter-defibrillator

• Carers and comforters

• Case–control study

• Cell death

• Charged-particle equilibrium

• Chronic exposure

• Class SR-0 gases

• Class SR-1 gases

• Class SR-2 gases

• Clearance

• Clearance level

• Clinical audit

• Clonogenic cells

• Clonogenic survival

• Clonogenic surviving fraction

• Cobblestone area cell assay (see Cobblestone area forming cell assay)

• Cobblestone area forming cell assay

• Collective dose

• Co-expertise

• Cohort study

• Collective dose

• Collective effective dose

• Collimation

• Colony

• Commissioning

• Committed effective dose

• Committed equivalent dose

• Compartment

• Compartment (environmental)

• Complex tissues

• Computed tomography dose index

• Concentration ratio

• Cone beam computed tomography

• Connective tissue

• Consequential late effects

• Constancy test

• Containment

• Contamination

• Coronary heart disease

• Cosmic radiation

• Cost-benefit analysis

• Coster-Kronig transition

• CR (see Concentration ratio)

• Cross section

• Cumulative air kerma (see Air kerma at the patient entrance reference point)

• Cumulative dose

• Curie

• Cytokines

D

• DAC (see Derived air concentration)

• DBT (see Digital breast tomosynthesis)

• DCRL (see Derived consideration reference level)

• DD (see Doubling dose)

• DDI, detector dose indicator (see Exposure index)

• DIL (see Derived investigation level)

• DDREF (see Dose and dose-rate effectiveness factor)

• Decay constant

• Decommissioning

• Decontamination

• Decontamination factor

• Dental and maxillofacial imaging

• Deontological Ethics

• Deposition

• Derived air concentration

• Derived consideration reference level

• Derived investigation level

• Derived limit

• Derived reference level

• Designated area

• Detector dose indicator (see Exposure index)

• Detector quantum efficiency

• Deterministic effect

• Detriment

• Detriment-adjusted risk

• Diagnostic reference level

• Diastasis

• Dicentric chromosome

• Dichotomous

• Differentiation

• Digital breast tomosynthesis

• Dignity

• Direct bioassay

• Directional dose equivalent H’(d,Ω)

• Disposal

• Disposal facility

• Distribution coefficient (K_d)

• DLP (see Dose-length product)

• DNA damage signalling

• Dose (of ionising radiation)

• Dose and dose-rate effectiveness factor

• Dose coefficient

• Dose commitment

• Dose constraint

• Dose conversion coefficient

• Dose conversion convention

• Dose conversion factor

• Dose criteria

• Dose of record (E)

• Dose of record Hp (10)

• Dose equivalent in an organ or tissue

• Dose limit

• Dose modifying factor

• Dose per content function

• Dose per unit intake coefficient

• Dose rate

• Dose rate effectiveness factor

• Dose-length product

• Dose-threshold hypothesis

• Dose-rate effect

• Dose-response function

• Dose-threshold

• Doubling dose

• DQE (see Detector quantum efficiency)

• DRL (see Diagnostic reference level)

• DRL process

• DRL quantity

• DRL value

• DS02

• DS86

E

• EAR (see Excess absolute risk)

• Early normal tissue responses

• Edema

• Effect Dose 50

• Effect modifier

• Effective charge number

• Effective dose, E

• Effective dose equivalent

• Effective half-life

• EI (see Exposure index)

• Electron-capture decay

• Electrophysiology

• Elemental dose

• ELR (i.e. Excess Lifetime Risk, see Lifetime risk estimates)

• Emergency

• Emergency exposure situation

• Emergency plan

• Emergency preparedness

• Emergency procedures

• Employer

• Endogeneous excretion

• Endosteal tissue (see Endosteum)

• Endosteum

• Environmental exposure

• Environmental radiation protection

• Epigenetic effects

• Epithelium

• Equieffective dose

• Equilibrium equivalent concentration

• Equilibrium factor

• Equity

• Equivalent dose

• ERR (see Excess relative risk)

• Erythropoietin

• Ethics

• Evacuation

• Excess absolute risk

• Excess lifetime risk (see Lifetime risk estimates)

• Excess relative risk

• Excretion rate (instantaneous)

• Exclusion

• Exempt waste

• Exemption level

• Existing exposure situation

• Exogenous excretion

• Expanded and aligned radiation field

• Expanded radiation field

• Exponential survival curve

• Exposed individuals

• Exposure, external or internal

• Exposure (in the context of inhalation)

• Exposure index

• Exposure pathway

• Exposure situation

• Extrathoracic airways

F

• Fairness

• Field-size effect (Volume effect)

• Flexible tissues

• Fluence, Φ

• Fluoroscopically guided interventions

• Fluoroscopically or computed tomography guided interventions

• Forbiddenness

• Fractional absorption in the gastrointestinal tract, f₁

• Fractionation

• Fractionation and dose delivery patterns

• Fractionation sensitivity

• Frequent flyer

• FSU (see Functional subunits)

• Functional subunits

G

• Galactic cosmic radiation

• Gamma ray

• Gastrointestinal syndrome

• Gastrulation

• Gastroschisis

• GATA binding protein 2

• GATA-2 (see GATA binding protein 2)

• Genomic integrity

• Geomagnetic cut-off rigidity (see Rigidity threshold)

• Graded approach

• Graft vs host disease

• Granulocyte colony-stimulating factor

• Granulocyte-macrophage colony-stimulating factor

• Gray (Gy)

• Ground-level enhancement

• Growth factor

• Growth fraction

• Growth hormone (somatotropin)

H

• Habitual mouth breather

• Habitual nose breather

• Half-life, physical

• HATM (see Human Alimentary Tract Model]

• Hazard

• Health Surveillance

• Heliosphere

• Hereditary effect

• Hierarchical tissues

• High level waste

• High linear energy transfer radiation

• Homologous recombination

• Hormones

• Hounsfield unit

• Human Alimentary Tract Model

• Human respiratory tract model

• Hyperbaric oxygen

• Hyperfractionation

• Hypertrophic cardiomyopathy

• Hypoplasia

I

• ICRU 4-element tissue

• ICRU sphere

• Immune system

• IMRT (see Intensity-modulated radiotherapy)

• In vivo radiobioassay

• Incidence

• Incidence rate (see Incidence)

• Incident

• Inclusiveness

• Individual decontamination

• Individual monitoring

• Individual-related

• Induced genomic instability

• Informed consent

• Inhalability

• Inner bremsstrahlung

• Institutional control

• Intervention

• Intensity-modulated radiotherapy

• Intake

• Intermediate level waste

• Internal conversion electron

• Interphase death

• Intervention Level

• Interventional procedure

• Investigation level

• Iso-effect plots

• Isomers

• Isotropic geometry

• Itinerant (radiation) worker

J

• Justice

• Justification

K

• Kerma, K

• Kerma approximation

• Kp index

L

• Late normal tissue responses

• Latent time/period or latency interval

• LD_50/30

• LET (see Linear energy transfer)

• Licensee

• Life Span Study

• Lifetime risk

• Lifetime risk estimates

• Limitation of dose

• Lineal energy

• Linear dose response

• Linear energy transfer

• Linear-non-threshold model

• Linear-quadratic dose response model

• LLE (see Lifetime risk estimates)

• Local DRL

• Loss of Life Expectancy (see Lifetime risk estimates)

• Low Earth orbit

• Low dose

• Low dose rate

• Low level waste

• Low linear energy transfer radiation

• LSS (see Life Span Study)

• Lymphatic system

M

• Macrophage colony stimulating factor

• Magnetosphere

• Marrow cellularity

• Mass median diameter

• MDCT (see Multi-detector computed tomography)

• Mean glandular dose

• Measured quantity

• Medical exposure

• Member of the public

• Mendelian diseases

• Mitigation

• MMD (see Mass median diameter)

• Molecular imaging

• Multifactorial diseases

• Multiplicative risk projection model

• Multistage carcinogenesis model

• Multistage tumorigenesis

• Multitarget equation

• Multi-detector computed tomography

• Mutation component

• Myocardial perfusion

• Myocardial stress test

N

• National radon survey

• National DRL

• Naturally occurring radioactive material

• Necrosis

• Neurological syndrome

• Neurovascular syndrome

• NHEJ (see Non-homologous end joining)

• Noise (in imaging)

• Nominal value

• Nominal risk coefficient

• Non-cancer diseases

• Non-homologous end joining

• Non-maleficence

• Non-sphericity parameter

• Non-targeted effects

• Normal tissue complication probability

• Notification value (in CT)

• Nuclear medicine

• Nuclear track detectors

O

• OAR (see Organ at risk)

• Occupancy factor

• Occupational exposure

• OEA (see Oxygen enhancement ratio)

• OLINDA/EXM

• Oncogene

• Operating management

• Operational quantities

• Optimisation

• Optimisation of protection

• Organ absorbed dose (see Organ/tissue absorbed dose)

• Organ at risk

• Organ dose equivalent

• Organ/tissue absorbed dose

• Other (systemic) tissues

• Orphan source

• Oversight

• Oxygen enhancement ratio

P

• Particle fluence (see Fluence)

• Particle transport

• Particle radiance

• Patient entrance reference point

• Peak skin dose

• Pelagic

• Pencil beam

• Percutaneous coronary intervention

• Pericarditis

• Personal dose equivalent, H_p(d)

• Phantom

• Pharynx

• Pilomatricoma

• Planned exposure situation

• Platelet-derived growth factor

• PLDR (see Potentially lethal damage repair)

• Pooled analysis

• Population risk

• Potential alpha energy concentration

• Potential exposure

• Potential recoverability correction factor

• Potentially lethal damage repair

• Practical radiological protection culture

• Practice

• PRCF (see Potential recoverability correction factor)

• Prevailing circumstances

• Principle of application of dose limits

• Principle of justification

• Principle of optimisation

• Principles of protection

• Procedural values

• Progenitor cell

• Programmed cell death

• Projected dose

• Protection quantities

• Protection strategy

• Protective action

• Protective action guide

• Prudence

• Public exposure

Q

• Qualified expert

• Quality control testing (x-ray equipment)

• Quality factor, Q(L)

• Quasi-threshold dose

R

• Radiation belt

• Radiation detriment (see Detriment)

• Radiation modifier

• Radiation risk

• Radiation safety officer

• Radiation source

• Radiation weighting factor, w_R

• Radiation-induced second cancer

• Radiation worker

• Radioactive dispersion device

• Radioactive source

• Radioactive substance

• Radioactive waste

• Radioactivity

• Radiofrequency ablation

• Radiographer

• Radiological attack

• Radiological controlled area

• Radiological protection principles

• Radionuclides of natural origin

• Radioresponsiveness

• Radiosensitiser

• Radiosensitivity, cellular

• Radon progeny

• Radon-prone area

• RAP (see Reference Animal and Plant)

• Ras

• Rb

• RBE (see Relative biological effectiveness)

• Reactive oxygen species

• Reasonableness

• Recovery

• Recovery responder

• Recovery (cellular or tissue)

• Redox

• Reference air kerma

• Reference Animal and Plant

• Reference bioassay function

• Reference biokinetic model

• Referrer

• Reference female (see Reference Individual)

• Reference individual

• Reference level

• Reference male (see Reference Individual)

• Reference parameter value

• Reference Person

• Reference phantom

• Reference value

• Reference worker

• Region

• Regional diagnostic reference levels

• Registry

• REID (see Lifetime risk estimates)

• Rigidity threshold

• Rehabilitation of living conditions

• Relative biological effectiveness

• Relative life lost

• Relative risk

• Relative survival

• Relocation

• Remedial action

• Remediation

• Repopulation

• Representative organism (non-human biota)

• Representative person

• Reproductive integrity

• Residual dose

• Respiratory protection

• Response function (see Dose-response function)

• Retrievability

• Reversibility

• Right to know

• Rigidity threshold

• Rigidity

• Ring chromosome

• Risk

• Risk coefficient

• Risk model

• Risk of exposure-induced death (see (see Lifetime risk estimates)

• ROS (see Reactive oxygen species)

• Routine monitoring

• RR (see Relative risk)

S

• S coefficient (radiation weighted) S_W[(r_T←r_s)]

• SAF (see Specific absorbed fraction)

• Safety case

• Safety

• Safety culture

• Scintigraphy

• Sealed source

• Secondary radiation

• Security

• Security screening

• SEE (see Specific effective energy]

• Self-help protection

• Senescence

• Severe deterministic injury

• Sheltering

• Shielding

• Sievert (Sv)

• Size-specific dose estimate

• SLDR (see Sublethal damage repair)

• Slice (in CT & CBCT)

• Slow repair

• SOBP (see Spread-out Bragg peak)

• Solar cosmic radiation

• Solar cycle

• Solar flare

• Solar particle event

• Solar wind

• Somatic effect

• Source (see Radiation source)

• Source region

• Source term

• Source-related

• Source-related assessment

• South Atlantic anomaly

• Special (non-routine) monitoring

• Specific absorbed fraction

• Specific effective energy

• Spongiosa

• Spontaneous fission

• Spread-out Bragg peak

• Stakeholder

• Standard-size adult

• Stem cell

• Stenosis

• Stochastic effect

• Storage

• Subcutaneous tissue

• Sublethal damage repair

• Substantial radiation dose level

• Superposition principle (in dosimetry)

• Supervised area

• Surface contamination

• Systemic model

T

• Tachycardia

• Target region

• Target tissue

• Targeted effects

• Telangiectasia

• Teratocarcinoma

• Thermodynamic diameter

• Thoracic airways

• Threshold dose for tissue reactions

• Threshold levels

• Tissue absorbed dose (see Organ/tissue absorbed dose)

• Thoron progeny

• Thyroid blocking

• Time factor

• Time-resolved computed tomography

• Tissue equivalent material

• Tissue reaction

• Tissue weighting factor

• Tolerability

• Tolerance dose

• Track structure

• Transfer compartment

• Transfer of risk

• Transfer rate

• Transforming growth factor

• Transgenerational effect

• Translocation

• Transmission detection system

• Transparency

• Transport of risk (see Transfer of risk)

• Tumour suppressor gene

• Trapped particles

• Treatment preparation in radiotherapy

• Trophic level

• Types of materials

• Typical value

U

• Unattached fraction

• Unsealed source

• Upper reference levels

• Uptake

• Utilitarian ethics

V

• Value judgement

• Valvular heart disease

• Virtue ethics

• Voxel phantom

W

• Waste disposal

• Waste management

• Wisdom

• WL (see Working level)

• WLM (see Working level month)

• Worker

• Working level

• Working level month

• w_T (see Tissue weighting factor)

• w_R (see Radiation weighting factor)

X

• X ray

• Xerostomia

Y

Z

...

• α/β value

• α/β ratio (see α/β value)

• γH2AX foci