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ICRP Publication 103
The 2007 Recommendations of theInternational Commission on
Radiological Protection

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Annals of the ICRPPUBLICATION 103

The 2007 Recommendations of the International
Commission on Radiological Protection

EditorJ. VALENTIN

PUBLISHED FOR
The International Commission on Radiological ProtectionbyAnnals of the ICRP
Published on behalf of the International Commission
on Radiological Protection
Aims and Scope
The International Commission on Radiological Protection (ICRP) is the primary body in protection against ionisingradiation. ICRP is a registered charity and is thus an independent non-governmental organisation created by the1928 International Congress of Radiology to advance for the public beneﬁt the science of radiological protection.
The ICRP provides recommendations and guidance on protection against the risks associated with ionishing radiation, from artiﬁcial sources widely used in medicine, general industry and nuclear enterprises, and from naturally
occurring sources. These reports and recommendations are published four times each year on behalf of the ICRP as
the journal Annals of the ICRP. Each issue provides in-depth coverage of a speciﬁc subject area.
Subscribers to the journal receive each new report as soon as it appears so that they are kept up to date on the latest
developments in this important ﬁeld. While many subscribers prefer to acquire a complete set of ICRP reports andrecommendations, single issues of the journal are also available separately for those individuals and organizations
needing a single report covering their own ﬁeld of interest. Please order through your bookseller, subscription agent,or direct from the publisher.
ICRP is composed of a Main Commission and ﬁve standing Committees on: radiation eﬀects, doses from radiation
exposure, protection in medicine, the application of ICRP recommendations, and protection of the environment, allserved by a small Scientiﬁc Secretariat. The Main Commission consists of twelve members and a Chairman.
Committees typically comprise 15–20 members. Biologists and medical doctors dominate the current membership;
physicists are also well represented.
ICRP uses Working Parties to develop ideas and Task Groups to prepare its reports. A Task Group is usuallychaired by an ICRP Committee member and usually contains a majority of specialists from outside ICRP. Thus,
ICRP is an independent international network of specialists in various ﬁelds of radiological protection. At any one
time, about one hundred eminent scientists are actively involved in the work of ICRP. The Task Groups are assigned
the responsibility for drafting documents on various subjects, which are reviewed and ﬁnally approved by the Main
Commission. These documents are then published as the Annals of the ICRP.

International Commission on Radiological Protection
Chairman: Dr. L.-E. Holm, Swedish Radiation Protection Authority (SSI), SE-171 16 Stockholm, Sweden
Vice-Chairman: Dr. R. Cox, Health Protection Agency, Didcot, UK
Scientiﬁc Secretary: Dr. J. Valentin, ICRP, SE-171 16 Stockholm, Sweden; e-mail: scient.secretary@icrp.org

Members of the Main Commission of the ICRP
J.D. Boice Jr, Rockville, MD, USA
R.H. Clarke, Hampshire,
UK (Emeritus)
C. Cousins, Cambridge, UK
A.J. González, Vienna, Austria
J. Lee, Seoul, Korea
B. Lindell, Stockholm, Sweden(Emeritus)

Y. Sasaki, Tokyo, Japan
C.B. Meinhold, Brookhaven,
N. Shandala, Moscow, Russia
MD, USA (Emeritus)
W.K. Sinclair, Escondido, CA, USA (Emeritus)
F.A. Mettler Jr., Albuquerque,
C. Streﬀer, Essen, Germany
NM, USA (Emeritus)
A. Sugier, Fontenay-aux-Roses, France
Z. Pan, Beijing, China
R.J. Pentreath, Cornwall, UK
R.J. Preston, Research Triangle Park,
NC, USAThis report was drafted by the following Task Group
Full members
B.C. Winkler, Centurion, South Africa
R.M. Alexakhin, Obninsk, Russia(z 2003)(to 2005)
J.D. Boice Jr., Rockville, MD
C. Cousins, Cambridge, UK
R. Cox, Chilton, UK(from 2005)
A.J. González, Buenos Aires, Argentina L.-E. Holm, Stockholm, Sweden
F.A. Mettler Jr., Albuquerque, NM
H. Menzel, Geneva, Switzerland(to 2005)(2004-)
R.J. Pentreath, Cornwall, UK (from 2003) R.J. Preston, Research Triangle Park,NC (from 2005)
N. Shandala, Moscow, Russia
C. Streﬀer, Essen, Germany(from 2005)
Corresponding members
P. Burns, Yallambie, VA

J. Cooper, Chilton, UK

J. Valentin, Stockholm, Sweden(Scientiﬁc Secretary)
R.H. Clarke, Hampshire, UK(to 2005)
G.J. Dicus, Poolesville, MD (z 2005)
J.-K. Lee, Seoul, R. Korea(from 2005)
Z.Q. Pan, Beijing, P.R. China
Y. Sasaki, Tokyo, Japan
A. Sugier, Paris, France (from 2003)

ICRP Publication 103

The 2007 Recommendations of
the International Commission on RadiologicalProtection
ICRP Publication 103
Approved by the Commission in March 2007
Abstract–These revised Recommendations for a System of Radiological Protection formallyreplace the Commission’s previous, 1990, Recommendations; and update, consolidate, anddevelop the additional guidance on the control of exposure from radiation sources issued since
1990.
Thus, the present Recommendations update the radiation and tissue weighting factors in thequantities equivalent and effective dose and update the radiation detriment, based on the latest
available scientific information of the biology and physics of radiation exposure. They
maintain the Commission’s three fundamental principles of radiological protection, namely
justification, optimisation, and the application of dose limits, clarifying how they apply toradiation sources delivering exposure and to individuals receiving exposure.
The Recommendations evolve from the previous process-based protection approach using
practices and interventions by moving to an approach based on the exposure situation. They
recognise planned, emergency, and existing exposure situations, and apply the fundamental
principles of justification and optimisation of protection to all of these situations. They
maintain the Commission’s current individual dose limits for effective dose and equivalentdose from all regulated sources in planned exposure situations. They re-inforce the principle of
optimisation of protection, which should be applicable in a similar way to all exposure
situations, subject to the following restrictions on individual doses and risks; dose and risk
constraints for planned exposure situations, and reference levels for emergency and existing
exposure situations. The Recommendations also include an approach for developing aframework to demonstrate radiological protection of the environment.
Ó 2007 ICRP. Published by Elsevier Ltd. All rights reserved.
Keywords: Justification; Optimisation; Dose limits; Constraints; Reference Levels

1

ICRP Publication 103

Editorial
WE COULD NOT HAVE DONE IT WITHOUT YOUR HELPThe new recommendations of the International Commission on Radiological Protection were adopted on 21 March 2007, Essen, Germany, after eight years of discussions, involving scientists, regulators, and users all around the world.
The Commission is an advisory body that oﬀers its recommendations to regulatory and advisory agencies, mainly by providing guidance on the fundamental principles on which appropriate radiological protection can be based. Since its inception
in 1928, the Commission has regularly issued recommendations regarding protection
against the hazards of ionising radiation. The ﬁrst report in the current series, Publication 1, contained the recommendations adopted in 1958 (ICRP, 1959). The more
recent recommendations have appeared as Publication 26 (ICRP, 1977), and Publication 60 (ICRP, 1991b), and contain the recommendations adopted in 1977 and1990, respectively.
International organisations and national authorities responsible for radiologicalprotection, as well as the users, have taken the recommendations and principles issued by the Commission as a key basis for their protective actions. As such, virtually
all international standards and national regulations addressing radiological protection are based on the Commission’s recommendations.
Currently, most national regulations are based on the 1990 Recommendations in
Publication 60. International standards, such as the International Basic Safety Standards, various international labour conventions, and European directives on radiological protection are also based on these recommendations.
In Publication 26, the Commission quantiﬁed the risks of stochastic eﬀects of radiation and proposed a system of dose limitation with its three principles of justiﬁcation, optimisation of protection, and individual dose limitation. In Publication 60,
the Commission revised its recommendations and extended its philosophy to a system of radiological protection while keeping the fundamental principles ofprotection.
New scientiﬁc data have been published since Publication 60, and while the biological and physical assumptions and concepts remain robust, some updating is required. The overall estimate of deterministic eﬀects remain fundamentally thesame. The estimates of cancer risk attributable to radiation exposure have not changed greatly in the past 17 years, whereas the estimated risk of heritable eﬀects is currently lower than before. The new data provide a ﬁrmer basis on which to modelrisks and assess detriment.
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ICRP Publication 103

The 2007 Recommendations evolve from the previous process-based approach ofpractices and interventions to an approach based on the characteristics of radiation
exposure situations. The system of radiological protection applies in principle to any
situation of radiation exposure. Similar procedures are used for deciding on the extent and level of protective actions, regardless of exposure situation. Speciﬁcally, theprinciples of justiﬁcation and optimisation apply universally. ICRP is of the opinion
that by focusing more on optimisation, the implementation of protection for what
has until now been categorised as interventions could be enhanced.
In view of the importance aﬀorded to the Commission’s recommendations and toensure that the new recommendations adequately and appropriately address national issues and concerns, the Commission has initiated a much more open process
than that used for the development of the previous recommendations. It should also
be noted that the Commission mentions, for the ﬁrst time, the need to account for
the views and concerns of stakeholders when optimising protection.
The Commission has therefore solicited input from a broad spectrum of radiological protection stakeholders, ranging from government institutions and internationalorganisations to scientists and non-governmental organisations. The draft recommendations have been discussed at a large number of international and national conferences and by the many international and national organisations with an interest inradiological protection.
Many of these also arranged particular activities around the Recommendations
project. Thus for instance, the International Radiation Protection Association arranged reviews through its member organisations world-wide for their 2000 and2004 Congresses and in connection with our 2006 public consultation, the Nuclear
Energy Agency of the OECD organised seven international workshops and performed four detailed assessments of draft ICRP texts (in 2003, 2004, 2006, and2007), and the European Commission organised a seminar in 2006 to debate the scientiﬁc issues in the Recommendations. The United Nations agencies, with the International Atomic Energy Agency as the lead agency, are using the 2007 ICRP
Recommendations as a major input to their project of revising the International Basic Safety Standards, and likewise the European Commission uses the 2007 Recommendations as a major input to their revision of the European Basic Safety
Standards.
The Recommendations have been prepared after two phases of international public consultation. By following this policy of transparency and involvement of stakeholders, ICRP is expecting a clearer understanding and wide acceptance of its
Recommendations. Although the revised Recommendations do not contain any fundamental changes to the radiological protection policy, they will help to clarify application of the system of protection in the plethora of exposure situations encountered,
thereby improving the already high standards of protection.
The Commission is pleased at having arrived at the end of a long but useful gestation phase including numerous consultations and is proud to present these 2007
Recommendations. The extensive consultations resulted in a much improved document and the Commission is grateful to the many organisations, experts, and individual members of the public who have devoted so much of their time and4

ICRP Publication 103

experience to helping us to improve the Recommendations. Their contributions havebeen crucial for the future success of the 2007 Recommendations.
LARS-ERIK HOLM
CHAIRMAN, ICRP

References
ICRP, 1959. Recommendations of the International Commission on Radiological Protection. ICRP
Publication 1. Pergamon Press, Oxford, UK.
ICRP, 1977. Recommendations of the International Commission on Radiological Protection. ICRP
Publication 26, Ann. ICRP 1 (3).
ICRP, 1991b. 1990 Recommendations of the International Commission on Radiological Protection. ICRP
Publication 60, Ann. ICRP 21 (1–3).

5

TABLE OF CONTENTS
ABSTRACT ..........................................................................................................

1

EDITORIAL.........................................................................................................

3

TABLE OF CONTENTS .....................................................................................

7

PREFACE.............................................................................................................

9

EXECUTIVE SUMMARY ................................................................................

11

References ...........................................................................................................

16

GLOSSARY........................................................................................................

17

1. INTRODUCTION .........................................................................................

35
35
35
39
40

1.1.
1.2.
1.3.
1.4.

The history of the Commission...........................................................................
The development of the Commission’s Recommendations ................................
Structure of the Recommendations ....................................................................
References ...........................................................................................................

2. THE AIMS AND SCOPE OF THE RECOMMENDATIONS ...................
2.1.
2.2.
2.3.
2.4.
2.5.

The aims of the Recommendations ....................................................................
The basis and structure of the system of protection...........................................
The scope of the Recommendations ...................................................................
Exclusion and exemption ....................................................................................
References ...........................................................................................................

3. BIOLOGICAL ASPECTS OF RADIOLOGICAL PROTECTION .............
3.1.
3.2.
3.3.
3.4.
3.5.
3.6.

The induction of deterministic effects (harmful tissue reactions) .......................
The induction of stochastic effects......................................................................
The induction of diseases other than cancer.......................................................
Radiation effects in the embryo and fetus..........................................................
Judgements and uncertainties .............................................................................
References ...........................................................................................................

4. QUANTITIES USED IN RADIOLOGICAL PROTECTION ....................
4.1.
4.2.
4.3.
4.4.
4.5.
4.6.

Introduction ........................................................................................................
Considerations of health effects ..........................................................................
Dose quantities....................................................................................................
Assessment of radiation exposure .......................................................................
Uncertainties and judgements .............................................................................
References ...........................................................................................................

7

41
41
42
45
46
47
49
49
50
56
57
57
58
61
61
61
62
71
77
78

ICRP Publication 103

5. THE SYSTEM OF RADIOLOGICAL PROTECTION
OF HUMANS............................................................................................
5.1.
5.2.
5.3.
5.4.
5.5.
5.6.
5.7.
5.8.
5.9.
5.10.
5.11.

6. IMPLEMENTATION OF THE COMMISSION’SRECOMMENDATIONS .............................................................................
6.1.
6.2.
6.3.
6.4.
6.5.
6.6.
6.7.

81

The definition of a source ................................................................................. 82
Types of exposure situations ............................................................................. 82
Categories of exposure ...................................................................................... 83
The identification of the exposed individuals ................................................... 84
Levels of radiological protection....................................................................... 87
The principles of radiological protection .......................................................... 88
Justification ....................................................................................................... 89
Optimisation of protection................................................................................ 91
Dose constraints and reference levels................................................................ 93
Dose limits ......................................................................................................... 98
References ........................................................................................................ 100

Planned exposure situations ..............................................................................
Emergency exposure situations .........................................................................
Existing exposure situations..............................................................................
Protection of the embryo/fetus in emergency and existing exposure situation.
Comparison of radiological protection criteria.................................................
Practical implementation...................................................................................
References .........................................................................................................

7. MEDICAL EXPOSURE OF PATIENTS, COMFORTERS AND
CARERS, AND VOLUNTEERS in BIOMEDICAL RESEARCH ...........

103
103
108
111

115
116
118
122

Justification for medical procedures .................................................................
Optimisation of protection in medical exposures .............................................
Effective dose in medical exposure ...................................................................
Exposure of patients who are pregnant ............................................................
Accident prevention in external beam therapy and brachytherapy ..................
Protection of carers and comforters of patients treated with radionuclides.....
Volunteers for biomedical research...................................................................
References .........................................................................................................

125
126
128
129
129
130
130
131
132

8. PROTECTION OF THE ENVIRONMENT ..............................................

133

7.1.
7.2.
7.3.
7.4.
7.5.
7.6.
7.7.
7.8.

8.1.
8.2.
8.3.

The objectives of radiological protection of the environment .......................... 133
Reference Animals and Plants .......................................................................... 134
References ......................................................................................................... 135

ANNEX A. BIOLOGICAL AND EPIDEMIOLOGICAL INFORMATIONON HEALTH RISKS ATTRIBUTABLE TO IONISINGRADIATION................................................................................................ 137
ANNEX B. QUANTITIES USED IN RADIOLOGICAL PROTECTION .... 247
ALL REFERENCES........................................................................................
8321

PREFACE
Since issuing its 1990 Recommendations as ICRP Publication 60 (ICRP 1991b),
the Commission has reviewed these Recommendations regularly and, from time totime, has issued supplementary reports in the Annals of the ICRP. The extent of these
supplementary reports has indicated the need for the consolidation and rationalisation presented here. New scientiﬁc data have also been published since Publication
60, and while the biological and physical assumptions and concepts remain robust,some updating is required. The overall estimates of deterministic eﬀects and stochastic risk remain fundamentally the same. The overall estimates of cancer risk attributable to radiation exposure have not changed appreciably in the past 16 years.
Conversely, the estimated risk of heritable eﬀects is currently lower than before.
Overall, the new data provide a ﬁrmer basis on which to model risks and assess detriment. Finally, it has also become apparent that the radiological protection of theenvironment should receive more emphasis than in the past.
Therefore, while recognising the need for stability in international and national
regulations, the Commission has decided to issue these revised Recommendations
having two primary aims in mind:
 to take account of new biological and physical information and of trends in thesetting of radiation safety standards; and to improve and streamline the presentation of the Recommendations.
In addition, the Commission has maintained as much stability in the Recommendations as is consistent with the new scientiﬁc information and societal expectations.
In its revised System of Protection, the Recommendations of the Commission now
evolve from the previous process-based approach of practices and interventions to
an approach based on the characteristics of radiation exposure situations. In taking
this approach, the Commission wishes to aﬃrm that its system of protection can beapplied in principle to any situation of radiation exposure. Similar procedures areused for deciding on the extent and level of protective actions, regardless of exposure
situation. Speciﬁcally, the principles of justiﬁcation and optimisation apply universally. The Commission is of the opinion that the implementation of protection forwhat has until now been categorised as interventions could be enhanced by increasing the attention to these common features.
These Recommendations were produced by the Main Commission of ICRP, basedon an earlier draft that was subjected to public and internal consultation in 2004 andagain, in revised form, in 2006. By introducing more transparency and by involving
the many organisations and individuals having an interest in radiological protectionin the revision process, the Commission is expecting a better common understanding
and acceptance of its Recommendations.
The membership of the Main Commission during the period of preparation of thepresent Recommendations was:9

ICRP Publication 103(2001–2005)
R.H. Clarke (Chairman) A.J. González
R.M. Alexakhin
L.-E. Holm (Vice-Chairman)
J.D. Boice jr
F.A. Mettler jr
R. CoxZ.Q. Pan
G.J. Dicus (z 2006)
R.J. Pentreath (2003–2005)
Scientiﬁc Secretary: J. Valentin

Y. Sasaki
C. Streﬀer
A. Sugier (2003–2005)
B.C. Winkler (z 2003)(2005–2009)
L.-E. Holm (Chairman)
J.-K. Lee
J.D. Boice jr
H. Menzel (2007–2009)
C. Cousins
Z.Q. Pan
R. Cox (Vice-Chairman)
R.J. Pentreath
A.J. González
R.J. Preston
Scientiﬁc Secretary: J. Valentin

Y. Sasaki
N. Shandala
C. Streﬀer (2005–2007)
A. Sugier

The work of the Commission was greatly aided by signiﬁcant contributions from
P. Burns, J. Cooper, J.D. Harrison, and W. Weiss. It also beneﬁted from discussions
at many international meetings on the present Recommendations.
The Commission wishes to express its appreciation to all international and national organisations, governmental as well as non-governmental, and all individuals
who contributed in the development of these Recommendations.

10

EXECUTIVE SUMMARY(a) On 21 March 2007, the Main Commission of the International Commission on
Radiological Protection (ICRP) approved these revised Recommendations for a System of Radiological Protection which formally replace the previous Recommendations issued in 1991 as Publication 60 (ICRP, 1991b) and update the additional
guidance on the control of exposure from radiation sources issued since Publication
60. These revised Recommendations consolidate and develop the previous Recommendations and guidance.
(b) The Commission has prepared these Recommendations after two phases ofinternational public consultation, one in 2004 and one in 2006, on draft Recommendations. By following this policy of transparency and involvement of stakeholders,the Commission is anticipating a clearer understanding and wider acceptance of
its Recommendations.
(c) The major features of the present Recommendations are:
 Updating the radiation and tissue weighting factors in the quantities equivalentand eﬀective dose, and updating the radiation detriment based on the latest available scientiﬁc information of the biology and physics of radiation exposure; Maintaining the Commission’s three fundamental principles of radiological protection, namely justiﬁcation, optimisation, and the application of dose limits,and clarifying how they apply to radiation sources delivering exposure and toindividuals receiving exposure; Evolving from the previous process-based protection approach using practices
and interventions, by moving to a situation-based approach applying the fundamental principles of justiﬁcation and optimisation of protection to all controllable
exposure situations, which the present Recommendations characterise as planned,
emergency, and existing exposure situations; Maintaining the Commission’s individual dose limits for eﬀective dose and equivalent dose from all regulated sources in planned exposure situations – these limits
represent the maximum dose that would be accepted in any planned exposure situations by regulatory authorities; Re-enforcing the principle of optimisation of protection, which should be applicable in a similar way to all exposure situations, with restrictions on individual doses
and risks, namely dose and risk constraints for planned exposure situations andreference levels for emergency and existing exposure situations; and Including an approach for developing a framework to demonstrate radiologicalprotection of the environment.
(d) The Commission’s system of radiological protection applies to all exposures toionising radiation from any source, regardless of its size and origin. However, theRecommendations can apply in their entirety only to situations in which either thesource of exposure or the pathways leading to the doses received by individuals
can be controlled by some reasonable means. Some exposure situations are excluded
from radiological protection legislation, usually on the basis that they are unamenable to control with regulatory instruments, and some exposure situations are
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ICRP Publication 103

exempted from some or all radiological protection regulatory requirements wheresuch controls are regarded as unwarranted.
(e) An understanding of the health eﬀects of ionising radiation is central to theCommission’s Recommendations. Following a review of the biological and epidemiological information on the health risks attributable to ionising radiation, theCommission has reached the following conclusions. The distribution of risks todiﬀerent organs/tissues is judged to have changed somewhat since Publication 60,
particularly in respect of the risks of breast cancer and heritable disease. However,assuming a linear response at low doses, the combined detriment due to excess
cancer and heritable eﬀects remains unchanged at around 5% per Sv. Embodied
in this current estimate is the use of a dose and dose-rate eﬀectiveness factor forsolid cancers which is unchanged at a value of 2. The Commission also judges
that, following prenatal exposure, a) cancer risk will be similar to that following
irradiation in early childhood and b) threshold dose exists for the induction of
malformations and for the expression of severe mental retardation. The Commission has retained the eﬀective dose limits and the equivalent dose limits for theskin, hands/feet, and eye given in Publication 60 but recognises that further information is needed and revised judgements may be required particularly in respect of
the eye. The available data on possible excess in non-cancer diseases (e.g., cardiovascular disorders) are judged to be insuﬃcient to inform on risks at low doses.
(f) The Commission’s extensive review of the health eﬀects of ionising radiation
has, however, not indicated that any fundamental changes are needed to the systemof radiological protection. Importantly, existing numerical recommendations in thepolicy guidance issued since 1991 remain valid unless otherwise stated. Therefore,
these revised Recommendations should not imply any substantial changes to radiological protection regulations that are based on its previous Recommendations andsubsequent policy guidance.
(g) The central assumption of a linear dose–response relationship for the inductionof cancer and heritable eﬀects, according to which an increment in dose induces a
proportional increment in risk even at low doses, continues to provide the basis
for the summation of doses from external sources of radiation and from intakesof radionuclides.
(h) The use of equivalent and eﬀective dose remains unchanged, but a number ofrevisions have been made to the methods used in their calculation. Reviews of therange of available data on the relative biological eﬀectiveness of diﬀerent radiations,
together with biophysical considerations, have led to changes to the values of radiation weighting factors used for neutrons and protons, with values for neutrons
given as a continuous function of neutron energy, and the inclusion of a value forcharged pions. Radiation weighting factors for photons, electrons, muons, and alphaparticles are unchanged.
(i) An important change is that doses from external and internal sources will becalculated using reference computational phantoms of the human body based on
medical tomographic images, replacing the use of various mathematical models.
For adults, equivalent doses will be calculated by sex-averaging of values obtainedusing male and female phantoms. Eﬀective dose will then be calculated using revised
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ICRP Publication 103

age- and sex-averaged tissue weighting factors, based on updated risk data and intended to apply as rounded values to a population of both sexes and all ages. Eﬀective dose is calculated for a Reference Person and not for an individual.
(j) Eﬀective dose is intended for use as a protection quantity. The main uses ofeﬀective dose are the prospective dose assessment for planning and optimisation inradiological protection, and demonstration of compliance with dose limits for regulatory purposes. Eﬀective dose is not recommended for epidemiological evaluations,nor should it be used for detailed speciﬁc retrospective investigations of individual
exposure and risk.
(k) The collective eﬀective dose quantity is an instrument for optimisation, forcomparing radiological technologies and protection procedures, predominantly inthe context of occupational exposure. Collective eﬀective dose is not intended asa tool for epidemiological risk assessment, and it is inappropriate to use it in risk
projections. The aggregation of very low individual doses over extended time periods is inappropriate, and in particular, the calculation of the number of cancer
deaths based on collective eﬀective doses from trivial individual doses should be
avoided.
(l) In order to assess radiation doses, models are necessary to simulate the geometry of the external exposure, the biokinetics of incorporated radionuclides, and thehuman body. The reference models and necessary reference parameter values are
established and selected from a range of experimental investigations and humanstudies through judgements. For regulatory purposes, these models and parametervalues are ﬁxed by convention and are not subject to uncertainty. The Commission
is aware of uncertainties and lack of precision of the models and parameter values.
Eﬀorts are undertaken to critically evaluate and to reduce the uncertainties. For individual retrospective dose and risk assessments, individual parameters and uncertainties have to be taken into account.
(m) The Commission’s process of consolidation of previous guidance and recommendations has indicated that some changes to the structure and terminology of thesystem of protection were desirable in order to improve clarity and utility. In particular the distinction between practices and interventions may not have been clearly
understood in the wider radiological protection community. Additionally, there were
exposure situations which were diﬃcult to categorise in this manner.
(n) The Commission now recognises three types of exposure situations which replace the previous categorisation into practices and interventions. These three exposure situations are intended to cover the entire range of exposure situations. The
three situations are:
 Planned exposure situations, which are situations involving the planned introduction and operation of sources. (This type of exposure situation includes situations
that were previously categorised as practices.) Emergency exposure situations, which are unexpected situations such as those that
may occur during the operation of a planned situation, or from a malicious act,
requiring urgent attention.

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ICRP Publication 103

 Existing exposure situations, which are exposure situations that already exist whena decision on control has to be taken, such as those caused by natural backgroundradiation.
(o) The three key principles of radiological protection are retained in the revised
Recommendations. The principles of justiﬁcation and optimisation apply in all three
exposure situations whereas the principle of application of dose limits applies only fordoses expected to be incurred with certainty as a result of planned exposure situations. These principles are deﬁned as follows: The Principle of Justiﬁcation: Any decision that alters the radiation exposure situation should do more good than harm.
 The Principle of Optimisation of Protection: The likelihood of incurring exposure,the number of people exposed, and the magnitude of their individual doses should
all be kept as low as reasonably achievable, taking into account economic andsocietal factors.
 The Principle of Application of Dose Limits: The total dose to any individual from
regulated sources in planned exposure situations other than medical exposure ofpatients should not exceed the appropriate limits speciﬁed by the Commission.
The Commission continues to distinguish amongst three categories of exposure:
occupational exposures, public exposures, and medical exposures of patients (andcomforters, carers, and volunteers in research). If a female worker has declared that
she is pregnant, additional controls have to be considered in order to attain a level ofprotection for the embryo/fetus broadly similar to that provided for members of the
public.
(p) The revised Recommendations emphasise the key role of the principle of optimisation. This principle should be applied in the same manner in all exposure situations. Restrictions are applied to doses to a nominal individual (the Reference
Person), namely dose constraints for planned exposure situations and reference levels
for emergency and existing exposure situations. Options resulting in doses greater inmagnitude than such restrictions should be rejected at the planning stage. Importantly, these restrictions on doses are applied prospectively, as with optimisation
as a whole. If, following the implementation of an optimised protection strategy,
it is subsequently shown that the value of the constraint or reference level is exceeded, the reasons should be investigated but this fact alone should not necessarily
prompt regulatory action. The Commission expects that this emphasis on a common
approach to radiological protection in all exposure situations will aid application of
the Commission’s Recommendations in the various circumstances of radiation
exposure.
(q) The relevant national authorities will often play a major role in selecting values
for dose constraints and reference levels. Guidance on the selection process is provided in the revised Recommendations. This guidance takes account of numerical
recommendations made previously by the Commission.
(r) Planned exposure situations encompass sources and situations that have been
appropriately managed within the Commission’s previous Recommendations for
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ICRP Publication 103

practices. Protection during the medical uses of radiation is also included in this typeof exposure situation. The process of planning protection in planned exposure situations should include consideration of deviations from normal operating procedures
including accidents and malicious events. Exposures arising in such circumstances
are referred to by the Commission as potential exposures. Potential exposures are
not planned but they can be anticipated. The designer and the user of a source must
therefore take actions to reduce the likelihood of a potential exposure happening,such as assessing the probability of an event and introducing engineering safeguardscommensurate to this probability. Recommendations for planned exposure situations are substantially unchanged from these provided in Publication 60 and subsequent publications. The dose limits for occupational and public exposures forpractices are retained for application to regulated sources in planned exposure
situations.
(s) Radiological protection in medicine includes the protection not only of patients
but also of individuals exposed to radiation whilst caring for or comforting patients,and volunteers involved in biomedical research. The protection of all of these groups
requires special consideration. The Commission’s Recommendations for radiologicalprotection and safety in medicine are given in Publication 73 (ICRP 1996a) which has
been further elaborated in a series of publications. The recommendations, guidance
and advice in these publications remain valid and are summarised in the present Recommendations and in Publication 105 (ICRP, 2007b) which was drafted by ICRP
Committee 3 to support these Recommendations.
(t) Emphasis on optimisation using reference levels in emergency and existing
exposure situations focuses attention on the residual level of dose remaining after
implementation of protection strategies. This residual dose should be below the reference level, which represents the total residual dose as a result of an emergency, orin an existing situation, that the regulator would plan not to exceed. These exposure
situations often involve multiple exposure pathways which means that protection
strategies involving a number of diﬀerent protective actions will have to be considered. The process of optimisation will however continue to use the dose averted
by speciﬁc countermeasures as an important input into the development of optimised
strategies.
(u) Emergency exposure situations include consideration of emergency preparedness and emergency response. Emergency preparedness should include planning forthe implementation of optimised protection strategies which have the purpose of
reducing exposures, should the emergency occur, to below the selected value ofthe reference level. During emergency response, the reference level would act as abenchmark for evaluating the eﬀectiveness of protective actions and as one input into
the need for establishing further actions.
(v) Existing exposure situations include naturally occurring exposures as well as
exposures from past events and accidents, and practices conducted outside the Commission’s Recommendations. In this type of situation, protection strategies will often
be implemented in an interactive, progressive manner over a number of years. Indoor radon in dwellings and workplaces is an important existing exposure situationand is one where the Commission made speciﬁc recommendations in 1994 in
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Publication 65 (ICRP 1993b). Since then several epidemiological studies have conﬁrmed the health risk from radon exposure and have generally provided support
for the Commission’s Recommendations on protection against radon. Consistent
with its approach to radiological protection in the revised Recommendations, theCommission now recommends that national authorities should set national reference
levels as an aid to optimisation of protection against radon exposures. For the sakeof continuity and practicability, the Commission retains the upper value of 10 mSv(eﬀective dose, converted by convention from 600 Bq m3 Rn-222 in dwellings) for
the annual dose reference level, as given in Publication 65. The Commission reaﬃrms
that radon exposure at work at levels above the national reference level should beconsidered part of occupational exposure whereas exposures at levels below shouldnot. Nevertheless, optimisation is a requirement below the national reference level.
(w) The revised Recommendations acknowledge the importance of protecting theenvironment. The Commission has previously concerned itself with mankind’s environment only with regard to the transfer of radionuclides through it, mainly in thecontext of planned exposure situations. In such situations, the Commission continues to believe that the standards of environmental control needed to protect the general public would ensure that other species are not placed at risk. To provide a soundframework for environmental protection in all exposure situations, the Commission
proposes the use of Reference Animals and Plants. In order to establish a basis for
acceptability, additional doses calculated to these reference organisms could be compared with doses known to have speciﬁc biological eﬀects and with dose rates normally experienced in the natural environment. The Commission, however, does
not propose to set any form of ‘dose limits’ for environmental protection.
(x) The Commission anticipates that although the revised Recommendations do
not contain any fundamental changes to the radiological protection policy, these
Recommendations will help to clarify application of the system of protection in
the plethora of exposure situations encountered, thereby further improving the already high standards of protection.

References
ICRP, 1991b. 1990 Recommendations of the International Commission on Radiological Protection. ICRP
Publication 60. Ann. ICRP 21 (1–3).
ICRP, 1993b. Protection against radon-222 at home and at work. ICRP Publication 65. Ann. ICRP
23 (2).
ICRP, 1996a. Radiological protection in medicine. ICRP Publication 73. Ann. ICRP 26 (2).
ICRP, 2007b. Radiological protection in medicine. ICRP Publication 105. Ann. ICRP 37 (5).

16

GLOSSARY
a=b ratio
A measure of the curvature of the cell survival curve and a measure of the sensitivity of a tissue or tumour to dose fractionation. The dose at which the linear
and quadratic components of cell killing are equal.
Absorbed dose, D
The fundamental dose quantity given by
D¼

de
dm

where de is the mean energy imparted to matter of mass dm by ionising radiation. The SI unit for absorbed dose is joule per kilogram (J kg1) and its specialname is gray (Gy).
Active (red) bone marrow
The organ system bone marrow contains the cell systems for the formation ofblood cells starting from the pluripotent haematopietic stem cells to the mature
blood cells.
Activity, A
The expectation value of the number of nuclear transformations occurring in agiven quantity of material per unit time. The SI unit of activity is per second(s1) and its special name is becquerel (Bq).
Activity Median Aerodynamic Diameter (AMAD)
The value of aerodynamic diameter such that 50% of the airborne activity in a
speciﬁed aerosol is associated with particles greater than the AMAD. Used
when deposition depends principally on inertial impaction and sedimentation,
typically when the AMAD is greater than about 0.5 lm.
Adaptive response
A post-irradiation cellular response which, typically, serves to increase theresistance of the cell to a subsequent radiation exposure.
Ambient dose equivalent, H*ð10Þ
The dose equivalent at a point in a radiation ﬁeld that would be produced by
the corresponding expanded and aligned ﬁeld in the ICRU sphere at a depth of
10 mm on the radius vector opposing the direction of the aligned ﬁeld. The unitof ambient dose equivalent is joule per kilogram (J kg1) and its special name issievert (Sv).
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ICRP Publication 103

Annual intake, AI
The amount of a speciﬁed radionuclide entering the human body by ingestion
or inhalation within one year.
Apoptosis
An active biochemical process of programmed cell death following radiation orother insults.
Averted dose
The dose prevented or avoided by the application of a protective measure or setof protective measures, i.e., the diﬀerence between the projected dose if the protective measure(s) had not been applied and the expected residual dose.
Baseline rates
The annual disease incidence observed in a population in the absence of exposure to the agent under study.
Becquerel (Bq)
The special name for the SI unit of activity, 1 Bq = 1 s1 (2.7 1011 Ci).
BioassayAny procedure used to determine the nature, activity, location, or retention ofradionuclides in the body by in vivo measurement or by in vitro analysis ofmaterial excreted or otherwise removed from the body.
Biological half-life
The time required, in the absence of further input, for a biological system orcompartment to eliminate, by biological processes, half the amount of a substance (e.g., radioactive material) that has entered it.
Brachytherapy
Radiation treatment of a patient using sealed or unsealed sources of radiation
placed within the patient’s body.
Bystander effectA response in unirradiated cells that is triggered by signals received from irradiated neighbouring cells.
Categories of exposure
The Commission distinguishes between three categories of radiation exposure:
occupational, public, and medical exposures of patients.
Collective dose
See ‘Collective eﬀective dose’.
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Collective effective dose, S
The collective eﬀective dose due to individual eﬀective dose values between E1
and E2 from a speciﬁed source within a speciﬁed time period DT is deﬁned
as:
Z E2  dN
E
dE
SðE1 ; E2 ; DT Þ ¼
dE DT
E1It can be approximated as S = Ri Ei Ni where Ei is the average eﬀective dose for a
subgroup i, and Ni is the number of individuals in this subgroup. The time period
and number of individuals over which the eﬀective doses are summed should always be speciﬁed. The unit of the collective eﬀective dose is joule per kilogram (Jkg1) and its special name is man sievert (man Sv). The number of individuals
experiencing an eﬀective dose in the range E1 to E2, N(E1, E2, DT) is
Z E2  dN
dE
N ðE1 ; E2 ; DT Þ ¼
dE DT
E1and the average value of eﬀective dose EðE1 ; E2 ; DT Þ in the interval of individual doses between E1 and E2 for the time period DT is:Z E2  1
dN
EðE1 ; E2 ; DT Þ ¼
EdE
N ðE1 ; E2 ; DT Þ E1
dE DT
Committed effective dose, EðsÞThe sum of the products of the committed organ or tissue equivalent doses andthe appropriate tissue weighting factors (wT), where s is the integration time inyears following the intake. The commitment period is taken to be 50 years for
adults, and to age 70 years for children.
Committed equivalent dose, HT ðsÞ
The time integral of the equivalent dose rate in a particular tissue or organ thatwill be received by an individual following intake of radioactive material into
the body by a Reference Person, where s is the integration time in years.
Confidence limits
An interval giving the lowest and highest estimate of a parameter that is
statistically compatible with the data. For a 95% conﬁdence interval, there is
a 95% chance that the interval contains the parameter.
Controlled area
A deﬁned area in which speciﬁc protection measures and safety provisions are,or could be, required for controlling normal exposures or preventing the spreadof contamination during normal working conditions, and preventing or limiting the extent of potential exposures. A controlled area is often within a supervised area, but need not be.
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DD
See ‘Doubling dose’.
Derived air concentration (DAC)This equals the annual limit on intake, ALI, (of a radionuclide) divided by thevolume of air inhaled by a Reference Person in a working year (i.e., 2.2 103 m3).
The unit of DAC is Bq m3.
Designated area
An area that is either ‘controlled’ or ‘supervised’.
Deterministic effectInjury in populations of cells, characterised by a threshold dose and an increasein the severity of the reaction as the dose is increased further. Also termed tissue reaction. In some cases, deterministic eﬀects are modiﬁable by post-irradiation procedures including biological response modiﬁers.
Detriment
The total harm to health experienced by an exposed group and its descendants
as a result of the group’s exposure to a radiation source. Detriment is a multidimensional concept. Its principal components are the stochastic quantities:
probability of attributable fatal cancer, weighted probability of attributablenon-fatal cancer, weighted probability of severe heritable eﬀects, and lengthof life lost if the harm occurs.
Detriment-adjusted risk
The probability of the occurrence of a stochastic eﬀect, modiﬁed to allow for
the diﬀerent components of the detriment in order to express the severity of
the consequence(s).
Diagnostic reference level
Used in medical imaging with ioning radiation to indicate whether, in routine
conditions, the patient dose or administered activity (amount of radioactive
material) from a speciﬁed procedure is unusually high or low for that procedure.
Directional dose equivalent, H 0 (d, )The dose equivalent at a point in a radiation ﬁeld that would be produced by
the corresponding expanded ﬁeld in the ICRU sphere at a depth, d, on a radius
in a speciﬁed direction, X. The unit of directional dose equivalent is joule perkilogram (J kg1) and its special name is sievert (Sv).
DMF
Dose modifying factor: the ratio of doses with and without modifying agents,
causing the same level of biological eﬀect.
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DNA damage signalling
Interacting biochemical processes which recognise and respond to
DNA damage in cells, e.g., by causing the arrest of the reproductive cell
cycle.
Differentiation
The process whereby stem cells enter a pathway of proliferation during whichdaughter cells acquire specialised functions.
Dose and dose-rate effectiveness factor (DDREF)
A judged factor that generalises the usually lower biological eﬀectiveness (perunit of dose) of radiation exposures at low doses and low dose rates as compared with exposures at high doses and high dose rates.
Dose coefficient
Used as a synonym for dose per unit intake of a radioactive substance, butsometimes 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.
Dose commitment, Ec
A calculational tool, deﬁned as the inﬁnite time integral of the per caput
dose rate E_ due to a speciﬁed event, such as a year of a planned activity
causing discharges. In the case of indeﬁnite discharges at a constant rate, themaximum annual per caput dose rate E_ in the future for the speciﬁed
population will be equal to the dose commitment of one year of practice, irrespective of changes in the population size. If the activity causing discharges is
continued only over a time period, s, the maximum future annual per
caput dose will be equal to the corresponding truncated dose commitment,deﬁned as
Z s_
Ec ðsÞ ¼
EðtÞdt0

Dose constraint
A prospective and source-related restriction on the individual dose from asource, which provides a basic level of protection for the most highly exposed
individuals from a source, and serves as an upper bound on the dose in optimisation of protection for that source. For occupational exposures, the dose constraint is a value of individual dose used to limit the range of options
considered in the process of optimisation. For public exposure, the dose constraint is an upper bound on the annual doses that members of the publicshould receive from the planned operation of any controlled source.
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Dose equivalent, H
The product of D and Q at a point in tissue, where D is the absorbed dose and
Q is the quality factor for the speciﬁc radiation at this point, thus:
H ¼ DQThe unit of dose equivalent is joule per kilogram (J kg1), and its special nameis sievert (Sv).
Dose limit
The value of the eﬀective dose or the equivalent dose to individuals fromplanned exposure situations that shall not be exceeded.
Dose of record, Hp ð10ÞThe eﬀective dose of a worker assessed by the sum of the measured personaldose equivalent Hp(10) and the committed eﬀective dose retrospectively determined for the Reference Person using results of individual monitoring of theworker and ICRP reference biokinetic and dosimetric computational models.
Dose of record may be assessed with site-speciﬁc parameters of exposure, suchas the type of materials and AMAD, but the parameters of the Reference Person shall be ﬁxed as deﬁned by the Commission. Dose of record is assigned to
the worker for purposes of recording, reporting and retrospective demonstration of compliance with regulatory dose limits.
Dose-threshold hypothesis
A given dose above background, below which it is hypothesised that the risk ofexcess cancer and/or heritable disease is zero. (See also Threshold dose for tissue reactions).
Doubling dose (DD)The dose of radiation (Gy) that is required to produce as many heritable mutations as those arising spontaneously in a generation.
DS02
Dosimetry System 2002, a system for estimating gamma and neutron exposure
under a large variety of situations and which allows the calculation of absorbed
dose to speciﬁc organs for members of the Life Span Study. DS02 improved on
the DS86 dose system.
DS86
Dosimetry System 1986, a system for estimating gamma and neutron
exposure under a large variety of situations and which then allowed the calculation of absorbed dose to speciﬁc organs for members of the Life Span
Study.
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Effective dose, E
The tissue-weighted sum of the equivalent doses in all speciﬁed tissues and organs of the body, given by the expression:
X X
X
E¼
wT
wR DT;R or E ¼
wT H T
T

R

T

where HT or wR DT,R is the equivalent dose in a tissue or organ, T, and wT is
the tissue weighting factor. The unit for the eﬀective dose is the same as for absorbed dose, J kg1, and its special name is sievert (Sv).
ELR
See ‘Lifetime risk estimates’.
Emergency
A non-routine situation or event that necessitates prompt action primarily to
mitigate a hazard or adverse consequences for human health and safety, qualityof life, property or the environment. This includes situations for which prompt
action is warranted to mitigate the eﬀects of a perceived hazard.
Emergency exposure situation
An unexpected situation that occurs during the operation of a practice, requiring urgent action. Emergency exposure situations may arise from practices.
EmployerAn organisation, corporation, partnership, ﬁrm, association, trust, estate, public or private institution, group, political or administrative entity, or other persons designated in accordance with national legislation, with recognised
responsibility, commitment, and duties towards a worker in her or his employment by virtue of a mutually agreed relationship. A self-employed person is regarded as being both an employer and a worker.
Equivalent dose, HT
The dose in a tissue or organ T given by:
X
wR DT;RHT ¼
R

where DT,R is the mean absorbed dose from radiation R in a tissue or organ T,
and wR is the radiation weighting factor. Since wR is dimensionless, the unit for
the equivalent dose is the same as for absorbed dose, J kg1, and its specialname is sievert (Sv).
Excess absolute risk
The rate of disease incidence or mortality in an exposed population minus thecorresponding disease rate in an unexposed population. The excess absoluterisk is often expressed as the additive excess rate per Gy or per Sv.
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Excess relative risk
The rate of disease in an exposed population divided by the rate of disease in an
unexposed population, minus 1.0. This is often expressed as the excess relativerisk per Gy or per Sv.
Exclusion
The deliberate exclusion of a particular category of exposure from the scope of
an instrument of regulatory control.
Exemption
The determination by a regulatory body that a source or practice activity
involving radiation need not be subject to some or all aspects of regulatory
control.
Existing exposure situation
A situation that already exists when a decision on control has to be taken,
including natural background radiation and residues from past practices thatwere operated outside the Commission’s recommendations.
Exposed individuals
The Commission distinguishes between three categories of exposed individuals:
workers (informed individuals), the public (general individuals), and patients,
including their comforters and carers.
Fluence (particle fluence), U
The quotient of dN by da, where dN is the number of particles incident upon asmall sphere of cross-sectional area da, thus:
U¼

dN
da

FSU
Functional subunits of tissues, e.g., nephrons in kidney, alveoli in lung.
Gray (Gy)The special name for the SI unit of absorbed dose: 1 Gy = 1 J kg1.
Growth factors
Molecules that act to control cell reproduction and proliferation/diﬀerentiationof a population of cells.
Incidence (incidence rate)
The rate of occurrence of a disease in a population within a speciﬁed period oftime, often expressed as the number of cases of a disease arising per 100,000
individuals per year (or per 100,000 person-years).
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Induced genomic instability
The induction of an altered cellular state characterised by a persistent increaseover many generations in the spontaneous rate of mutation or other genome-related changes.
Intake, I
Activity that enters the body through the respiratory tract or the gastrointestinal tract or the skin.
– Acute intake
A single intake by inhalation or ingestion, taken to occur instantaneously.
– Chronic intake
An intake over a speciﬁed period of time.
Justification
The process of determining whether either (1) a planned activity involving radiation is, overall, beneﬁcial, i.e. whether the beneﬁts to individuals and to society
from introducing or continuing the activity outweigh the harm (including radiation detriment) resulting from the activity; or (2) a proposed remedial action
in an emergency or existing exposure situation is likely, overall, to be beneﬁcial,i.e., whether the beneﬁts to individuals and to society (including the reduction
in radiation detriment) from introducing or continuing the remedial action outweigh its cost and any harm or damage it causes.
Kerma, K
The quotient of the sum of the kinetic energies, dEtr, of all charged particles
liberated by uncharged particles in a mass dm of material, and the mass dmof that material.
K¼

dEtr
dm

Kerma is deﬁned as a non-stochastic quantity and dEtr is the expectation valueof the sum of the kinetic energies. The unit for kerma is joule per kilogram (Jkg1) and its special name is gray (Gy).
LAR
See ‘Lifetime risk estimates’.
LD50
Dose that is lethal for half of the exposed individuals.
LET
See ‘Linear energy transfer’.
Licensee
The holder of a current legal document issued by the regulatory body granting
authorisation to perform speciﬁed activities related to an installation or activity.
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Life Span Study (LSS)
The long-term cohort study of health eﬀects in the Japanese atomic bomb survivors in Hiroshima and Nagasaki.
Lifetime risk estimates
Several types of lifetime risk estimates can be used to calculate the risk, over a
lifetime, that an individual will develop, or die from, a speciﬁc disease causedby an exposure: 1) the excess lifetime risk (ELR) which is the diﬀerence between
the proportion of people who develop or die from the disease in an exposed
population and the corresponding proportion in a similar population without
the exposure; 2) the risk of exposure-induced death (REID) which is deﬁned as
the diﬀerence in a cause-speciﬁc death rate for exposed and unexposed populations of a given sex and a given age at exposure, as an additional cause of death
introduced into a population; 3) loss of life expectancy (LLE) which describes
the decrease in life expectancy due to the exposure of interest; and 4) lifetime
attributable risk (LAR) which is an approximation of the REID and describes
excess deaths (or disease cases) over a follow-up period with population background rates determined by the experience of unexposed individuals. The LAR
was used in this report to estimate lifetime risks.
Linear dose response
A statistical model that expresses the risk of an eﬀect (e.g., disease or abnormality) as being proportional to dose.
Linear energy transfer ðL or LETÞThe average linear rate of energy loss of charged particle radiation in a medium, i.e., the radiation energy lost per unit length of path through a material.
That is, the quotient of dE by dl where dE is the mean energy lost by a charged
particle owing to collisions with electrons in traversing a distance dl in matter.
L¼

dE
dl

The unit of L is J m1, often given in keV lm1.
Linear-non-threshold (LNT) model
A dose-response model which is based on the assumption that, in the low dose
range, radiation doses greater than zero will increase the risk of excess cancer
and/or heritable disease in a simple proportionate manner.
Linear-quadratic dose response
A statistical model that expresses the risk of an eﬀect (e.g., disease, death, orabnormality) as the sum of two components, one proportional to dose (linear
term) and the other one proportional to the square of dose (quadraticterm).
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LLE
See ‘Lifetime risk estimates’.
MC
See ‘Mutation component’.
Mean absorbed dose in a tissue or organ (T), DT
The absorbed dose DT, averaged over the tissue or organ T, which is given by
eT
DT ¼
mT
where eT is the mean total energy imparted in a tissue or organ T, and mT is themass of that tissue or organ.
Medical exposure
Exposure incurred by patients as part of their own medical or dental diagnosis
or treatment; by persons, other than those occupationally exposed, knowingly,
while voluntarily helping in the support and comfort of patients; and by volunteers in a programme of biomedical research involving their exposure.
Mendelian diseases
Heritable diseases attributable to single-gene mutations.
Multifactorial diseases
Diseases that are attributable to multiple genetic and environmental factors.
Multistage tumorigenesis
The stepwise acquisition of cellular properties that can lead to the developmentof tumour from a single (target) cell.
Mutation component (MC)A quantity that provides a measure of the relative change in disease frequency
per unit relative change in mutation rate, i.e., a measure of responsiveness; MCvalues diﬀer for diﬀerent classes of heritable disease.
Nominal risk coefficient
Sex-averaged and age-at-exposure-averaged lifetime risk estimates for a representative population.
Non-cancer diseases
Somatic diseases other than cancer, e.g., cardiovascular disease and cataracts.
NORM (naturally occurring radioactive material)
Radioactive material containing no signiﬁcant amounts of radionuclides otherthan naturally occurring radionuclides. Material in which the activity
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concentrations of the naturally occurring radionuclides have been changed bysome process are included in NORM.
Occupational exposureThis refers to all exposure incurred by workers in the course of their work, withthe exception of1) excluded exposures and exposures from exempt activities involving radiation
or exempt sources; 2) any medical exposure; and 3) the normal local natural
background radiation.
Operating management
The person or group of persons that directs, controls, and assesses an organisation at the highest level. Many diﬀerent terms are used, including, e.g., chief
executive oﬃcer (CEO), director general (DG), managing director (MD), andexecutive group.
Operational quantities
Quantities used in practical applications for monitoring and investigating situations involving external exposure. They are deﬁned for measurements andassessment of doses in the body. In internal dosimetry, no operational dosequantities have been deﬁned which directly provide an assessment of equivalentor eﬀective dose. Diﬀerent methods are applied to assess the equivalent or eﬀective dose due to radionuclides in the human body. They are mostly based on
various activity measurements and the application of biokinetic models (computational models).
Optimisation of protection (and safety)
The process of determining what level of protection and safety makes exposures, and the probability and magnitude of potential exposures, as low as reasonably achievable, economic and societal factors being taken into account.
Particle fluence, U
See ‘Fluence’.
Personal dose equivalent, Hp ðdÞ
An operational quantity: the dose equivalent in soft tissue (commonly interpreted as the ‘ICRU sphere’) at an appropriate depth, d, below a speciﬁed pointon the human body. The unit of personal dose equivalent is joule per kilogram(J kg1) and its special name is sievert (Sv). The speciﬁed point is usually givenby the position where the individual’s dosimeter is worn.
Planned exposure situations
Everyday situations involving the planned operation of sources including decommissioning, disposal of radioactive waste and rehabilitation of the previously
occupied land. Practices in operation are planned exposure situations.
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Pooled analysis
An analysis of epidemiological data from several studies based on original datafrom those studies that are analysed in parallel.
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 or sequence of events of a probabilistic
nature, including equipment failures and operating errors.
PRCF (potential recoverability correction factor)
A set of factors that take account of knowledge that diﬀerent classes of germline mutation will show diﬀerent degrees of recoverability in live-born oﬀspring,i.e., through diﬀering capacities to allow completion of embryonic/fetal
development.
Principles of protection
A set of principles that apply equally to all controllable exposure situations: theprinciple of justiﬁcation, the principle of optimisation of protection, and theprinciple of application of limits on maximum doses in planned situations.
Progenitor cell
Undiﬀerentiated cell capable of limited proliferation.
Projected dose
The dose that would be expected to be incurred if no protective measure(s) – were
to be taken.
Protection quantities
Dose quantities that the Commission has developed for radiological protectionthat allow quantiﬁcation of the extent of exposure of the human body to ionising radiation from both whole and partial body external irradiation and fromintakes of radionuclides.
Public exposure
Exposure incurred by members of the public from radiation sources, excluding
any occupational or medical exposure and the normal local natural background radiation.
Quality factor, QðLÞThe factor characterising the biological eﬀectiveness of a radiation, based on
the ionisation density along the tracks of charged particles in tissue. Q is deﬁned as a function of the unrestricted linear energy transfer, L1 (often denotedas L or LET), of charged particles in water:
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8
L < 10 keV=lm><1QðLÞ ¼ 0:32L  2:2 10 6 L 6 100 keV=lm>
pﬃﬃﬃ:
300= LL > 100 keV=lm
Q has been superseded by the radiation weighting factor in the deﬁnition ofequivalent dose, but it is still used in calculating the operational dose equivalentquantities used in monitoring.
Radiation detriment
A concept used to quantify the harmful health eﬀects of radiation exposure in
diﬀerent parts of the body. It is deﬁned by the Commission as a function of several factors, including incidence of radiation-related cancer or heritable eﬀects,
lethality of these conditions, quality of life, and years of life lost owing to these
conditions.
Radiation weighting factor, wR
A dimensionless factor by which the organ or tissue absorbed dose is multiplied
to reﬂect the higher biological eﬀectiveness of high-LET radiations comparedwith low-LET radiations. It is used to derive the equivalent dose from the absorbed dose averaged over a tissue or organ.
Radioactive material
Material designated in national law or by a regulatory body as being subject toregulatory control because of its radioactivity, often taking account of bothactivity and activity concentration.
Radiological attack
The use of radioactive or nuclear materials for malicious purposes, such as
blackmail, murder, sabotage, or terrorism.
Random error
Errors that vary in a non-reproducible way. These errors can be treated statistically by use of the laws of probability.
RBE
See ‘Relative biological eﬀectiveness’.
Reference Animals and Plants
A Reference Animal or Plant is a hypothetical entity, with the assumed basic
characteristics of a speciﬁc type of animal or plant, as described to the generality of the taxonomic level of Family, with deﬁned anatomical, physiological,
and life-history properties, that can be used for the purposes of relating exposure to dose, and dose to eﬀects, for that type of living organism.
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Reference Male and Reference Female (Reference Individual)
An idealised male or female with characteristics deﬁned by the Commission forthe purpose of radiological protection, and with the anatomical and physiological characteristics deﬁned in the report of the ICRP Task Group on Reference
Man (Publication 89, ICRP 2002).
Reference Person
An idealised person for whom the organ or tissue equivalent doses are calculated by averaging the corresponding doses of the Reference Male and Reference Female. The equivalent doses of the Reference Person are used for the
calculation of the eﬀective dose by multiplying these doses by the corresponding tissue weighting factors.
Reference phantom
Voxel phantoms for the human body (male and female voxel phantoms basedon medical imaging data) with the anatomical and physiological characteristics
deﬁned in the report of the ICRP Task Group on Reference Man (Publication
89, ICRP 2002).
Reference value
The value of a parameter recommended by the Commission for use in a biokinetic model in the absence of more speciﬁc information, i.e., the exact value
used to calculate the dose coeﬃcients presented in the report. Reference values
may be speciﬁed to a greater degree of precision than that which would be chosen to reﬂect the uncertainty with which an experimental value is known, in order to avoid the accumulation of rounding errors in a calculation.
Reference level
In emergency or existing controllable exposure situations, this represents the level of dose or risk, above which it is judged to be inappropriate to plan to allow
exposures to occur, and below which optimisation of protection should be
implemented. The chosen value for a reference level will depend upon the prevailing circumstances of the exposure under consideration.
Relative biological effectiveness (RBE)The ratio of a dose of a low-LET reference radiation to a dose of the radiation considered that gives an identical biological eﬀect. RBE values vary withthe dose, dose rate, and biological endpoint considered. In radiologicalprotection, the RBE for stochastic eﬀects at low doses (RBEM) is of particularinterest.
Relative life lost
The ratio of the proportion of observed years of life lost among people dying ofa disease in an exposed population and the corresponding proportion in a similar population without the exposure.
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REID
See ‘Lifetime risk estimates’.
Relative survival
The ratio of the proportion of cancer patients who survive for a speciﬁed number of years (e.g., 5 years) following diagnosis to the corresponding proportion
in a comparable set of cancer-free individuals.
Representative Person
An individual receiving a dose that is representative of the more highly exposed
individuals in the population (see Publication 101, ICRP 2006a). This term isthe equivalent of, and replaces, ‘average member of the critical group’ described in previous ICRP Recommendations.
Residual dose
The dose expected to be incurred after protective measure(s) have beenfully
implemented (or a decision has been taken not to implement any protective
measures).
Risk constraint
A prospective and source-related restriction on the individual risk (in the senseof probability of detriment due to a potential exposure) from a source, which
provides a basic level of protection for the individuals most at risk from asource and serves as an upper bound on the individual risk in optimisationof protection for that source. This risk is a function of the probability of anunintended event causing a dose, and the probability of detriment due to that
dose. Risk constraints correspond to dose constraints but refer to potential
exposures.
SafetyThe achievement of proper operating conditions, prevention of accidents, or
mitigation of accident consequences.
Security
The prevention and detection of, and response to, theft, sabotage, unauthorised
access, illegal transfer, or other malicious acts involving nuclear material, otherradioactive substances, or their associated installations.
Sensitivity analysis
This aims to quantify how the results from a model depend upon the diﬀerent
variables included in it.
Sievert (Sv)
The special name for the SI unit of equivalent dose, eﬀective dose, and operational dose quantities. The unit is joule per kilogram (J kg1).
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SourceAn entity for which radiological protection can be optimised as an integral
whole, such as the x-ray equipment in a hospital, or the releases of radioactive
materials from an installation. Sources of radiation, such as radiation generators and sealed radioactive materials, and, more generally, the cause of exposure to radiation or to radionuclides.
Source region, Si
An anatomical region within the reference phantom body which contains theradionuclide following its intake. The region may be an organ, a tissue, the contents of the gastrointestinal tract or urinary bladder, or the surfaces of tissues
as in the skeleton, the alimentary tract, and the respiratory tract.
Specific absorbed fraction
The fraction of energy of that emitted as a speciﬁed radiation type in a source
region, S, that is absorbed in 1 kg of a target tissue, T.
Statistical power
The probability that an epidemiological study will detect a given level of elevated risk with a speciﬁed degree of conﬁdence.
Stem cell
Non-diﬀerentiated, pluripotent cell, capable of unlimited cell division.
Stochastic effects of radiation
Malignant disease and heritable eﬀects for which the probability of an eﬀect
occurring, but not its severity, is regarded as a function of dose without
threshold.
Supervised area
A deﬁned area not designated as a controlled area but for which occupational
exposure conditions are kept under review, even though no speciﬁc protection
measures or safety provisions are normally needed.
Systematic error
Errors that are reproducible and tend to bias a result in one direction. Theircauses can be assigned, at least in principle, and they can have constant andvariable components. Generally these errors cannot be treated statistically.
Target region, Ti
Anatomical region within the body (reference phantom) in which radiation isabsorbed. The region may be an organ or a speciﬁed tissue as in the gastrointestinal tract, urinary bladder, skeleton, and respiratory tract.
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Threshold dose for tissue reactions
Dose estimated to result in only 1% incidence of tissue reactions.
Tissue reaction
See ‘Deterministic eﬀect’.
Tissue weighting factor, wT
The factor by which the equivalent dose in a tissue or organ T is weighted torepresent the relative contribution of that tissue or organ to the total healthdetriment resulting from uniform irradiation of the body (ICRP 1991b). It isweighted such that:X
wT ¼ 1
T

Track structure
Spatial patterns of energy deposition in matter along the track from the passage of ionising radiation.
Transport of risk (also called transfer of risk)
Taking a risk coeﬃcient estimated for one population and applying it to another population with diﬀerent characteristics.
Voxel phantom
Computational anthropomorphic phantom based on medical tomographic
images where the anatomy is described by small three-dimensional volume elements (voxels) specifying the density and the atomic composition of the variousorgans and tissues of the human body.
WorkerAny person who is employed, whether full time, part time or temporarily, by an
employer, and who has recognised rights and duties in relation to occupational
radiological protection.
References for the Glossary
ICRP, 1991b. 1990 Recommendations of the International Commission on Radiological Protection. ICRP
Publication 60. Ann. ICRP 21 (1–3).
ICRP, 2002. Basic anatomical and physiological data for use in radiological protection. ICRP Publication
89. Ann. ICRP 32 (3/4).
ICRP, 2006a. Assessing dose of the representative person for the purpose of radiation protection of the
public and The optimisation of radiological protection: Broadening the process. ICRP Publication 101.
Ann. ICRP 36(3).

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