Safety Reports Series
N o. 7 1

Radiation Protectionin Paediatric Radiology

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RADIATION PROTECTION
IN PAEDIATRIC RADIOLOGYThe following States are Members of the International Atomic Energy Agency:
AFGHANISTANALBANIA
ALGERIAANGOLA
ARGENTINA
ARMENIA
AUSTRALIA
AUSTRIAAZERBAIJAN
BAHRAINBANGLADESH
BELARUSBELGIUM
BELIZEBENIN
BOLIVIABOSNIA AND HERZEGOVINABOTSWANABRAZIL
BULGARIA
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BURUNDICAMBODIACAMEROONCANADACENTRAL AFRICAN
REPUBLIC
CHAD
CHILE
CHINA
COLOMBIACONGOCOSTA RICA
CÔTE D’IVOIRECROATIACUBACYPRUSCZECH REPUBLIC
DEMOCRATIC REPUBLIC
OF THE CONGO
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FINLANDFRANCEGABONGEORGIAGERMANYGHANA
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HOLY SEE
HONDURASHUNGARYICELAND
INDIA
INDONESIA
IRAN, ISLAMIC REPUBLIC OFIRAQIRELANDISRAELITALY
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REPUBLICLATVIALEBANONLESOTHO
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LIBYA
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LITHUANIALUXEMBOURG
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MALAYSIAMALI
MALTA
MARSHALL ISLANDS
MAURITANIA
MAURITIUS
MEXICOMONACOMONGOLIAMONTENEGRO
MOROCCOMOZAMBIQUE
MYANMAR
NAMIBIANEPAL
NETHERLANDSNEW ZEALANDNICARAGUANIGERNIGERIANORWAYOMANPAKISTAN
PALAU
PANAMAPAPUA NEW GUINEAPARAGUAYPERU
PHILIPPINESPOLANDPORTUGALQATARREPUBLIC OF MOLDOVAROMANIARUSSIAN FEDERATIONRWANDASAUDI ARABIASENEGALSERBIASEYCHELLESSIERRA LEONESINGAPORESLOVAKIASLOVENIA
SOUTH AFRICASPAIN
SRI LANKA
SUDAN
SWEDENSWITZERLANDSYRIAN ARAB REPUBLICTAJIKISTANTHAILANDTHE FORMER YUGOSLAVREPUBLIC OF MACEDONIATOGOTRINIDAD AND TOBAGOTUNISIA
TURKEYUGANDAUKRAINE
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SAFETY REPORTS SERIES No. 71

RADIATION PROTECTION
IN PAEDIATRIC RADIOLOGY

INTERNATIONAL ATOMIC ENERGY AGENCY
VIENNA, 2012

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STI/PUB/1543

IAEA Library Cataloguing in Publication Data
Radiation protection in paediatric radiology. — Vienna : International Atomic
Energy Agency, 2012.
p. ; 24 cm. — (Safety reports series, ISSN 1020–6450 ; no. 71)
STI/PUB/1543
ISBN 978–92–0–125710–9
Includes bibliographical references.
1. Radiological, medical — Safety measures. 2. Pediatric radiology —Safety measures. 3. Diagnostic imaging. I. International Atomic Energy
Agency. II. Series.
IAEAL

12–00780

FOREWORD
Over the past decade and a half, special issues have arisen regarding theprotection of children undergoing radiological examinations. These issues havecome to the consciousness of a gradually widening group of concerned
professionals and the public, largely because of the natural instinct to protect
children from unnecessary harm. Some tissues in children are more sensitive toradiation and children have a long life expectancy, during which significant
pathology can emerge. The instinct to protect children has received further
impetus from the level of professional and public concern articulated in the wakeof media responses to certain publications in the professional literature.
Many institutions have highlighted the need to pay particular attention to
the special problems of protecting paediatric patients. The International
Commission on Radiological Protection has noted it and the IAEA’s General
Safety Requirements publication, Radiation Protection and Safety of Radiation
Sources: International Basic Safety Standards (BSS), requires it. This need has
been endorsed implicitly in the advisory material on paediatric computed
tomography scanning issued by bodies such as the US Food and Drug
Administration and the National Cancer Institute in the United States of America,
as well as by many initiatives taken by other national and regional radiologicalsocieties and professional bodies.
A major part of patient exposure, in general, and paediatric exposure, inparticular, now arises from practices that barely existed two decades ago. For
practitioners and regulators, it is evident that this innovation has been driven bothby the imaging industry and by an ever increasing array of new applications
generated and validated in the clinical environment. Regulation, industrial
standardization, safety procedures and advice on best practice lag (inevitably)
behind industrial and clinical innovations. This Safety Report is designed toconsolidate and provide timely advice on dealing with the special problems
involved.
The approach adopted is developed within the IAEA framework ofstatutory responsibility to establish standards for the protection of people against
exposure to ionizing radiation and to provide for the application of thesestandards. The BSS issued by the IAEA require the radiation protection ofpatients undergoing medical exposures through justification of the procedures
involved and optimization of protection and safety.
This challenge is taken up here by adding paediatric radiology to the areas
dealt with in recent IAEA publications. These are specifically Safety Reports
Series Nos 39 and 40 on diagnostic radiology and nuclear medicine, respectively,
and Safety Reports Series Nos 58–61 and 63 on newer medical imaging

techniques and other initiatives in justification of procedures and optimization ofprotection and safety.
The advice of the IAEA is intended in particular for professionals,
practitioners, and teachers and trainers in the area, as well as physicians referring
children for examinations. Resource materials and training materials are available
cost free on the IAEA’s Radiation Protection of Patients web site(http://rpop.iaea.org).
The IAEA wishes to thank V. Donoghue, J. Malone and O. Ciraj-Bjelac for
their assistance in reviewing the drafts of this publication at different stages ofpreparation. The IAEA officer responsible for this publication was M.M. Rehaniof the Division of Radiation, Transport and Waste Safety.

EDITORIAL NOTE
Although great care has been taken to maintain the accuracy of information contained inthis publication, neither the IAEA nor its Member States assume any responsibility forconsequences which may arise from its use.
The use of particular designations of countries or territories does not imply any
judgement by the publisher, the IAEA, as to the legal status of such countries or territories, of
their authorities and institutions or of the delimitation of their boundaries.
The mention of names of specific companies or products (whether or not indicated asregistered) does not imply any intention to infringe proprietary rights, nor should it beconstrued as an endorsement or recommendation on the part of the IAEA.
The IAEA has no responsibility for the persistence or accuracy of URLs for external or
third party Internet web sites referred to in this book and does not guarantee that any content
on such web sites is, or will remain, accurate or appropriate.

CONTENTS
1.

2.

INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1

1.1. Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.2. Objective and scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.3. Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1
2
3

FRAMEWORK FOR RADIATION PROTECTION
IN PAEDIATRIC RADIOLOGY . . . . . . . . . . . . . . . . . . . . . . . . . . . .

5

2.1. Basis for radiation protection in paediatric radiology . . . . . . . .
2.2. Justification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.2.1. General considerations . . . . . . . . . . . . . . . . . . . . . . . . . .
2.2.2. The physician’s and radiologist’s knowledge . . . . . . . .
2.2.3. Justification, the ICRP and the procedure . . . . . . . . . . .
2.2.4. Justification and the patient . . . . . . . . . . . . . . . . . . . . . .
2.2.5. Justification of medical exposures and dose limits . . . .
2.2.6. Non-medical procedures . . . . . . . . . . . . . . . . . . . . . . . .
2.2.7. Referral and/or appropriateness guidelines andclinical audit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.3. Optimization of protection and safety . . . . . . . . . . . . . . . . . . . .
2.3.1. Diagnostic reference levels . . . . . . . . . . . . . . . . . . . . . .
2.4. Dose limits and dose constraints for occupationally exposed
workers, carers and comforters, and members of the public . . .
2.5. Unnecessary exposures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.6. Special considerations associated with pregnancy . . . . . . . . . .
2.7. Research involving irradiation of children . . . . . . . . . . . . . . . .
2.8. Education and training . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.

4.

5
6
6
7
8
8
9
9
10
11
12
14
15
16
16
17

CONSIDERATIONS IN EQUIPMENT PROCUREMENT ANDIMMOBILIZATION OF PATIENTS . . . . . . . . . . . . . . . . . . . . . . . . .

18

3.1. Equipment procurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.2. Quality assurance of equipment . . . . . . . . . . . . . . . . . . . . . . . . .
3.3. Considerations in immobilization . . . . . . . . . . . . . . . . . . . . . . .

18
20
21

GENERAL RADIOLOGY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

22

4.1. Justification in film screen radiography, computed radiography
and digital radiography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

22

4.2. Optimization and general radiography . . . . . . . . . . . . . . . . . . . .
4.2.1. Optimization in film screen radiography . . . . . . . . . . . .
4.2.2. Doses and reference values for plain film radiography . . .
4.2.3. Mobile radiography . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.2.4. Optimization with computed radiography and digitalradiography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.3. Dental radiography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.3.1. Justification in dental radiography . . . . . . . . . . . . . . . . .
4.3.2. Optimization in dental radiography . . . . . . . . . . . . . . . .
5.

6.

7.

FLUOROSCOPY, FLUOROGRAPHY
AND INTERVENTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

24
24
26
29
30
33
34
35

38

5.1. Conventional fluoroscopy . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.1.1. Justification in conventional fluoroscopy . . . . . . . . . . .
5.1.2. Optimization of protection and safety in conventional
fluoroscopy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.2. Diagnostic and therapeutic interventional procedures . . . . . . . .
5.2.1. Justification in diagnostic and therapeutic interventional
procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.2.2. Optimization of protection and safety in diagnostic
and/or therapeutic interventional procedures . . . . . . . . .
5.3. Doses to paediatric patients and reference levels forfluoroscopy and interventional procedures . . . . . . . . . . . . . . . .
5.4. Doses to staff in fluoroscopy,
including interventional fluoroscopy . . . . . . . . . . . . . . . . . . . . .

38
38

51

COMPUTED TOMOGRAPHY . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

56

6.1.
6.2.
6.3.
6.4.

Justification in computed tomography . . . . . . . . . . . . . . . . . . . .
Optimization in computed tomography . . . . . . . . . . . . . . . . . . .
Computed tomography and diagnostic reference levels . . . . . .
Special techniques in computed tomography . . . . . . . . . . . . . .
6.4.1. Computed tomography interventions . . . . . . . . . . . . . . .
6.4.2. Cone beam dental computed tomography . . . . . . . . . . .

56
59
62
69
69
69

NUCLEAR MEDICINE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

71

7.1. Justification in nuclear medicine . . . . . . . . . . . . . . . . . . . . . . . .
7.2. Optimization and dose reduction in nuclear medicine . . . . . . . .

71
71

40
44
45
46
48

8.

SUMMARY AND CONCLUSIONS . . . . . . . . . . . . . . . . . . . . . . . . .

APPENDIX I:

76

BIOLOGICAL EFFECTS OF RADIATION IN
CHILDREN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

79

APPENDIX II: EXTRACT FROM THE EUROPEAN COMMISSION’SREFERRAL GUIDELINES FOR IMAGING . . . . . . . . .

81

APPENDIX III: EXPLANATION OF TERMS AND ADDITIONALDOSE DATA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

89

APPENDIX IV: DISTRIBUTION OF SCATTERED RADIATIONIN ROOMS DESIGNED FOR SPECIAL AND
INTERVENTIONAL PROCEDURES . . . . . . . . . . . . . .

94

APPENDIX V: TECHNICAL FACTORS AND DOSE IN COMPUTEDTOMOGRAPHY EXAMINATIONS . . . . . . . . . . . . . . .

95

APPENDIX VI: INSTRUCTIONS FOR THE CARE OF PAEDIATRICPATIENTS FOLLOWING DIAGNOSTIC NUCLEAR
MEDICINE EXAMINATIONS . . . . . . . . . . . . . . . . . . . .

99

REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CONTRIBUTORS TO DRAFTING AND REVIEW . . . . . . . . . . . . . . . . .

101
111

1. INTRODUCTION
1.1. BACKGROUND
Paediatric radiology involves imaging individuals with diseases ofchildhood and adolescence. The age range involved is defined differently in
different health care systems. The spectrum of diseases includes conditions
specific to very young children and many conditions common in the adult
population. Figures derived from the United Nations Scientific Committee on the
Effects of Atomic Radiation (UNSCEAR) suggest that about 250 million
paediatric radiological examinations (including dental examinations) per year
were performed worldwide between 1997 and 2007 [1]. Children undergoingthese examinations require special attention, both because of the diseases specificto childhood and the additional risks to them. In addition, children need special
care, in the form provided by parents, carers and comforters, as well as care thathas to be provided by specially trained health professionals.
Some tissues in children are more sensitive to the damaging effects ofionizing radiation than those in adults and special attention has to be paid to theamounts of radiation used [2–8]. A useful general summary of some of the reasonsfor this is given in Table 1 (taken from Ref. [9]). The extent of the overall
unnecessary paediatric dose and risk is uncertain but is currently a matter ofconsiderable concern [10, 11].
Organs and tissues are closer together in small children and, hence, areharder to exclude from the primary beam and to protect from scatter. They arealso distributed differently and are more susceptible to radiation damage. For
example, a computed tomography (CT) study of the lower extremities in an adultwill encounter almost exclusively fatty tissue in the bone marrow. In a child, asignificant proportion of the red marrow will be exposed, which is a much greater
cause for concern [11]. In addition, children have thinner layers of abdominal
visceral fat; hence, the natural contrast usually available in adults is much
reduced. Most radiation induced neoplasms do not manifest until several years
after exposure, so adult patients may die of other causes before they develop.
Owing to their longer life expectancy, children have a greater chance of living
long enough to develop a radiation induced neoplasm.
In practice, there is relatively little quantitative literature and audit of practiceon the protection of paediatric patients from radiation during diagnostic procedures.
This makes it difficult to gain knowledge and to justify whether this protection is
working. The benefits of a procedure need to be balanced against the possibility ofdamage occurring, although this can be difficult to quantify. However, even with a1

TABLE 1. REASONS FOR GREATER RISK IN PAEDIATRIC ASCOMPARED WITH ADULT COMPUTED TOMOGRAPHY [9]ReasonExplanation

Higher biological sensitivity
at same dose

More proliferating tissue;
different tissue distribution

Longer life expectancy

Late manifestation of radiation induced cancers

Increase in dose and effective dose
due to technical factors in radiology

Equipment often poorly adapted to paediatricradiology; smaller size and close proximity
of organs in children

dearth of literature, there is much that can be achieved. For example, relatively
simple advice on the following will yield dose savings:— Awareness of the special problems of patient positioning;— The need for immobilization techniques (including help from parents,
friends and technical aids);— The use of image quality assessment;— The importance of gonad protection;— The value and proper use of collimation;— The use of appropriate projections to minimize dose to high risk tissues;— The use of appropriate filters, mA modulation and/or special paediatricfactors with CT.
This publication brings together and summarizes the available advice on goodpractice in this area.

1.2. OBJECTIVE AND SCOPE
This publication provides guidance to radiologists, other clinicians andradiographers and/or technologists involved in diagnostic procedures using
ionizing radiation with children and adolescents. It will also be of value to
medical physicists and regulators. It is focused on the measures necessary toprovide protection from the harmful effects of radiation by meeting therequirements established in the International Basic Safety Standards (BSS) [2]and by according the necessary priority to this area. The emphasis throughout ison the special requirements of paediatric radiology with, where it is felt to be
helpful or necessary, limited restatement of operational aspects of patient andstaff protection widely used elsewhere in radiology.

2

Facility design, the physics of equipment, and radiology information
system and/or picture archiving and communication system (RIS/PACS) issues
are not addressed, with the exception of the section on procurement andmanagement of equipment in Section 3. This is included as paediatric facilities do
not always enjoy the support available to larger units for procurement purposes.
In keeping with current developments, additional attention is given tojustification, as is evident in IAEA and European Commission (EC) activities,
and in the Image Gently Campaign [10].
The only mandatory statements in this text are the requirements quoted
from the BSS [2]. Guidance provided here in the form of ‘should’ statements, or
simply in the present tense indicative, describing good practices, represents
expert opinion but does not constitute international consensus recommendations
on how to meet the relevant requirements.
There are certain requirements in the BSS [2] that, when applied to specificpractices, can be fulfilled mainly by means of one practical measure. In suchcases, the regulatory body may need to use a ‘should’ statement, which meansthat licensees should take this measure; if another measure is intended, an
equivalent level of protection and safety should be achieved. In other cases, there
may be more than one possible option. In such cases, the regulatory body would
mention them or describe them.

1.3. STRUCTURE
Section 2 presents the general framework for radiation protection ofpatients and staff in paediatric radiology, and includes a discussion on thejustification of medical exposures, which are sometimes neglected in radiology.
This section also deals with optimization; dose limits and constraints;
occupationally exposed workers, carers and comforters; pregnancy; staff training;
and research. Pertinent aspects of equipment procurement and/or management,
and of immobilization devices are addressed in Section 3. The main body of thetext is a series of sections treating the major radiological imaging modalities
including:— General, mobile and dental radiography, including film and/or digitalsystems (Section 4);— Fluoroscopy and interventions, both diagnostic and/or therapeutic(Section 5);— CT (Section 6);— Diagnostic nuclear medicine (Section 7).

3

With each, the issue of justification is considered and practical information
is provided, where possible, on optimization of protection and safety, including
the doses involved and their moderation and/or control.

42. FRAMEWORK FOR RADIATION PROTECTION
IN PAEDIATRIC RADIOLOGY
2.1. BASIS FOR RADIATION PROTECTION
IN PAEDIATRIC RADIOLOGY
The basis for radiation protection in paediatric radiology is well recognized.
It includes the requirement that there be a clear delineation of responsibility
extending from the level of the board of governors of the facility (e.g. a hospitalor clinic) involved, to the operational level. The requirement for involvement of
the hospital management and the need for a good operational structure which candeliver both the required technical and scientific advice and its effective
implementation in the clinical environment is also well recognized [2, 3, 12].
It is key to successful development, in this regard, that the head of
department be aware of and accept and discharge his or her responsibilities withrespect to radiation protection.
The licensee of the paediatric radiology facility, through theauthorization issued by the regulatory body, has the prime responsibility for
applying the relevant national regulations and meeting the conditions of thelicence. The licensee retains overall responsibility, but may appoint otherpeople to carry out actions and tasks related to these responsibilities. In
particular, the radiological medical practitioner1, the medical physicist2, themedical radiation technologist3 and the radiation protection officer4 (RPO) all
have key roles and responsibilities in radiation protection in the paediatricradiology facility.
A medical physicist needs to be available to fulfil, oversee or advise on
radiation protection requirements for imaging, calibration, dosimetry and quality

1

The term ‘radiological medical practitioner’ is defined in the BSS [2] (see Appendix III),and is used to cover the range of health professionals that include radiologists, nuclear
medicine physicians, radiation oncologists, cardiologists, dentists and other specialists thatmight use radiation. In this publication, the term ‘radiological medical practitioner’ is used
when the more general sense is appropriate and, at other times, the names of specific healthprofessionals are used when this gives better clarity.
2
The term ‘medical physicist’ is defined in the BSS [2] (see Appendix III).
3
The term ‘medical radiation technologist’ is defined in the BSS [2] (see Appendix III),and is used to cover the range of health professionals that are known by various terms in different
parts of the world, and include radiographers, radiation technologists and nuclear medicine
technicians.
4
The term ‘radiation protection officer’ is defined in the BSS [2] (see Appendix III).

5

assurance in paediatric radiology, and an RPO has to be available for radiation
protection matters with respect to staff and members of the public and to advise
on general regulatory requirements for radiation protection. In many cases, these
two roles may be carried out by one person, where that person is recognized ashaving the requisite specialist competence for both roles. The medical physicist
and the RPO also have to be closely involved in the development of thedepartment’s operational arrangements and its safety policies, and in monitoring,
reviewing and revising these arrangements.
In practice, a radiation protection committee is normally required, with thevarious stakeholders, including management, represented. A member of thedepartment is usually appointed as RPO. The RPO’s responsibilities include
monitoring the implementation of the committee’s policies. When a department issufficiently large to allow roles to be differentiated, the RPO may not hold key
departmental line management roles, such as head of department or chief medical
radiation technologist.
In practice, radiation protection relies on meeting requirements [2] that
apply three principles adopted in most regulatory systems throughout theworld [13, 14]. These requirements concern:— Justification of the activities or practices involved;— Optimization of protection and safety in the activities or practices involvedin terms of risks, costs, benefits, etc.;— Limitation of the doses received by various groups, including workers andthe general public.
Discussions of various aspects of these arrangements are available frommany sources [2–4, 12–14].

2.2. JUSTIFICATION
2.2.1.

General considerations

The benefits of many procedures that utilize ionizing radiation are wellestablished and well accepted both by the medical profession and society at large.
When a procedure involving radiation is medically justifiable, the anticipatedbenefits are almost always identifiable and are sometimes quantifiable. On theother hand, the risk of adverse consequences is often difficult to estimate andquantify. In its 1990 and 2007 recommendations, the International Commission
on Radiological Protection (ICRP) stated as a principle of justification that “Anydecision that alters the radiation exposure situation should do more good than

6

harm” [12–14]. A stronger position on justification of medical exposures is often
taken to the effect that the ‘good’ (i.e. the benefit) has to substantially outweighany risks that may be incurred, in part because of the uncertainty of the risks [15].
The ICRP has recommended a multi-step approach to the justification ofpatient exposures, and this is further discussed in Section 2.2.3 [12–14]. In thecase of the individual patient, justification normally involves both the referring
medical practitioner (who refers the patient, and may, for example, be thepatient’s physician and/or surgeon) and the radiological medical practitioner(under whose responsibility the examination is conducted) (see Appendix III).
Since 2007, there has been a heightened sensitivity to justification in
paediatric radiology. This has become more visible due to both concerns
emerging in scientific publications and events reported in the media [16–19].
More recently, the IAEA and the Alliance for Radiation Safety in Pediatric
Imaging (the Image Gently Campaign) have articulated these concerns and haveprovided both a structured approach to solutions and a forum for development in
the area [10, 20].
Justification for radiation exposure almost inevitably involves a physician
familiar with the patient and the medical history. Normally, an appropriately
qualified medical or dental practitioner (e.g. a radiologist, cardiologist or dentist)takes overall responsibility for the conduct of an examination and needs to workin close cooperation with the referring physician(s) in order to establish the mostappropriate procedure for the management of the patient.
It is particularly important with infants and children that the feasibility ofalternative techniques that do not use ionizing radiation (e.g. ultrasound andmagnetic resonance imaging (MRI)) be considered. This is even more important inchildren with chronic diseases. Some jurisdictions, for example, in the European
Union (EU), add a requirement that where an examination cannot be justified itshould be prohibited [5]. An effective way of improving good justification practiceis to include it as part of a programme of clinical audit [17, 21].
2.2.2.

The physician’s and radiologist’s knowledge

Education and training of both referring physicians and radiologists play a
crucial role in ensuring that justification works well in practice. Effective
justification requires that these physicians possess knowledge of the particularcase and its circumstances. Current experience and the published literaturesuggest that, in many clinical settings, the referring practitioner may have limited
awareness of the radiation doses and risks involved [15–18]. As advocated by the
Image Gently Campaign and many individual workers, it is essential that thoseactually performing the procedures be well informed [10, 20–24].

7

In practice, knowledge of the situation always has to be viewed in the context
of what can reasonably be expected. New knowledge can and needs to be acquiredas developments occur. The knowledge required for justification includes:— The clinical history, including examinations already performed;— Potential benefits of the action;— Awareness of short term and long term consequences, including the risks;— Up to date knowledge of any available alternative actions;— Knowledge of the consequences of not taking any action;— Knowledge of referral guidelines and/or acceptability criteria where they
are available.
2.2.3.

Justification, the ICRP and the procedure

The ICRP identifies three levels at which justification operates [12, 14].
Level 1 deals with the use of radiation in medicine in general. In practice, such
use is accepted as doing more good than harm to the patient, and its justification
is taken for granted. Level 2 deals with specified procedures with a specified
objective (e.g. chest radiographs for patients showing relevant symptoms). The
aim at this level is to judge whether the procedure will improve diagnosis orprovide necessary information about those exposed. Finally, Level 3 deals withthe application of the procedure to an individual (i.e. whether the particularapplication is judged to do more good than harm to the individual patient). In
practice, all individual medical exposures need to be justified in advance, by
taking into account the specific objectives of the exposure and the characteristicsof the individual patient.
2.2.4.

Justification and the patient

Each person, including children and adolescents, has dignity, and is entitled toa reasonable expectation of health. Respect for the dignity of each individual isgrounded in contemporary philosophical, social and legal thinking on the nature of
the person [15, 17, 18]. It has implications for the level of involvement of theindividual and/or their guardian or legal proxy in deciding whether a radiologicalexamination is required or appropriate. Thus, the individual is entitled to knowwhat is to happen [15, 22]. Parents of some children may desire to have information
about radiation risk, in particular for high dose examinations such as CT or
fluoroscopy guided interventions. Responsibility for providing this information
could lie with both the clinician requesting the study and the radiologist. In somesituations, the patient may be referred to a medical physicist for dose estimation.

8

In spite of concern, some patients may misinterpret radiation risk and may
refuse a useful or potentially life saving examination for fear of radiation. Thereis evidence that explaining the risk will not dissuade patients from undergoing theexamination, even when the risk is explained to parents of children in theradiation sensitive age group [23, 24]. However, this may not be universally true
and will depend upon the local conditions of societal and individual perception ofradiation risk. A brief information handout can improve parental understandingof the risk related to exposure to ionizing radiation, without causing parents torefuse studies recommended by the referring physician [10, 24]. Information onrisk to children undergoing high dose examinations may not interfere withappropriate care and may improve parental understanding.
Alternative approaches that induce confidence are likely to be very
powerful. These include assurance that the CT facility is certified by anappropriate body that oversees radiation doses to patients, that there is a system inplace for regular monitoring of radiation doses to patients and comparing withnational or international standards, and maintaining doses within the reference
levels. Patients and parents are likely to be satisfied more by the availability ofquality control and dose management mechanisms being in place rather than byinformation on radiation doses that the patient may not understand. A programmeof informing parents about the radiation risks associated with relatively high dose
procedures and the benefits of the procedure is a good practice.
2.2.5.

Justification of medical exposures and dose limits

The ICRP has recommended that dose limits not be applied to medical
exposures and, even with the higher radiation sensitivity of children, thisrecommendation is also applied to paediatric radiology. It is based on the fact thatthe exposed individual will derive benefit from the procedure, provided it has
been properly justified. The BSS state that dose limits are not to be applied to
medical exposures [2]. This approach has been adopted in all countries and, thus,
dose limits are not applied to patients for justified procedures [12].
2.2.6.

Non-medical procedures

Procedures involving exposure to ionizing radiation that may not yield
direct health benefits for the exposed individual may be permitted or required bylaw in some jurisdictions [25–27]. Examples include, but are not limited to,imaging required for security purposes, purposes of crime detection or
prevention, or medico-legal purposes of insurance companies or the courts.
Examples of areas where exposures of this type may arise in paediatric radiology

9include surveys of siblings in cases of suspected non-accidental injury, or age
determination in court cases or migration tribunals.
The justification for such practices sometimes involves consideration of the
public interest or the common good. Such practices are outside the scope of this
Safety Report, but it is noted that the BSS set out requirements for justificationand optimization for these practices [2].
2.2.7.

Referral and/or appropriateness guidelines and clinical audit

A number of tools are available to facilitate identification of the correct
radiological examination for a particular patient presentation. The most widely
known involve “appropriateness or referral criteria and/or guidelines”. Referral
guidelines provide advice on the appropriateness of imaging modalities andspecific examinations for many common clinical presentations. They also help
exclude inappropriate examinations. In addition, the radiation dose and thestrength of the evidence base for the advice offered are indicated. These
guidelines need to be available to all clinicians who request imaging studies onchildren and adolescents.
An updated version of the referral guidelines for paediatric radiology
published by the EC is reproduced in Appendix II [28, 29]. These guidelines
and/or criteria and their application in practice are under revision and are further
discussed in the justification sections of Sections 4–7. Further examples of
guidance include the appropriateness criteria developed by the American Collegeof Radiology in the United States of America, and the guidelines produced in the
United Kingdom [30, 31]. There is much variability in the extent to which thesetools are implemented in practice.
Tools of this type, or similar systems, are essential. In application, they
provide an effective ‘technology’ that has recently been reviewed and has beenshown to prevent inappropriate examinations and, thereby, reduce unnecessary
radiation doses in adults [17]. They also show promise with younger patients,
even though there is a dearth of studies in paediatric radiology [32]. Due to thevalue of such tools, the BSS require that relevant national or international referral
guidelines be taken into account in the justification of a given radiologicalprocedure for a given patient [2].
These tools have limitations in that they could be considered as advice andneed not be given the status of a legal or required standard of practice. They need
to be used with discretion in light of concrete situations, such as the immediately
accessible technology and the condition, age and social circumstances of thepatient. Regardless of the quality of the publicly available guidelines, there is a needfor special consideration in paediatric radiology because of the different patterns ofpresentation and distribution of diseases.

10

There is widespread pressure to use radiological imaging techniques toscreen for many diseases. In many cases, this form of health screening cannot bejustified for unselected populations based on the overall risks and benefits
involved. However, there may be considerable pressure from individual
professionals and the public to undertake programmes of radiological imaging for
health screening purposes.
While, to date, such pressures are not a feature of paediatric radiology, it isconceivable, given developments in the area, that they may arise in the future. If
this is the case, then such a proposed health screening programme for paediatrics
would need to be justified by the relevant health authority in conjunction withappropriate professional bodies [2]. This approach is similar to those alreadyestablished for selected groups (e.g. mammography for women in certain age
groups).
A neglected aspect of justification of medical exposures is the audit of its
effectiveness. Recent developments in clinical audit of radiology have included
approaches to audit of justification [17, 21, 33]. Referral and/or appropriatenessguidelines can provide a useful benchmark for audit. Some audit studies withadults have demonstrated the potential for significant sustainable dose savings in
the range of 20–50%. There is every reason to believe that such savings could
also be achieved in paediatric radiology. Considerable future activity is
anticipated in this area [17]. In a similar focus but strictly for radiation protection
purposes, the BSS have a requirement that a radiological review be performed
periodically, and this would include a critical review of the practical applicationof justification in the given facility [2].

2.3. OPTIMIZATION OF PROTECTION AND SAFETY
Once examinations are justified, they are required to be optimized(i.e. performed at a lower dose while maintaining efficacy and accuracy).
Optimization of the examination has to be generic for the examination type andall of the equipment and procedures involved. It will also be specific for theindividual, and include a review of whether or not it can be effectively done in a
way that reduces the dose for the particular patient. For example, can a lower
dose be used because less contrast or resolution is required, or because the patientis small, or can the irradiated volume be reduced?
Much of the material in Sections 4–7 can be viewed as contributing to the
optimization process, including diagnostic reference levels (DRLs), dose
constraints, good technique, good practice and optimized equipment subject to aregular quality assurance programme. Most of these areas need additional

11attention in paediatric radiology as the available literature is, for the most part,based on radiology studies in adults.
Regulatory systems generally recognize that patients benefit from medical
exposures. They essentially strike a bargain on behalf of society that dose limits
will not be applied to justified medical exposures. This bargain places the burdenof justification on the radiological medical practitioner and the referring
practitioner [2, 5].
Medical exposure also includes exposures of individuals, such as members of
the patient’s family, who comfort or care for the patient during a medical
exposure [12, 25]. This includes family members who help restrain a child during aprocedure. The definition of medical exposure is also extended to include exposuresthat are incurred as part of a programme of authorized biomedical research.
2.3.1.

Diagnostic reference levels

In the absence of dose limits, radiologists and other practitioners are often
concerned to establish whether their practice is reasonable and whether they areachieving satisfactory examinations at reasonable dose levels. The adoption anduse of paediatric protocols is paramount to achieving this goal in facilities in whichchildren are imaged.
A tool for optimization is the concept of DRLs. These act as a trigger for
review and are not intended to function as surrogate dose limits [12]. The BSS
mandate their use [2]. In practice, they tend to be set so that if the values involved
are exceeded, the radiological procedure involved needs to be investigated. This
does not mean that there is necessarily anything wrong occurring, rather that
there is something unusual which requires explanation, review and, possibly, a
new approach. The DRL for an examination is generally derived from a regionalor national survey of the doses for that examination. It is usually taken as the third
quartile dose value for the dose distribution obtained in the survey, i.e. the dosevalue below which 75% of doses lie [34].
This may be illustrated by examining the EC’s DRLs for 5 year old children
in Table 2 [35]. These were established by surveying the doses received for anumber of the more common projections in a range of institutions throughout the
EU in the early to mid-1990s. For general radiography, various projections ofchest, skull, abdomen, spine and pelvis are included. In practice, doses that wereeasy to measure, usually entrance surface dose (ESD), were taken. The
terminology currently employed, with updated approaches to dosimetry, isslightly different but the numerical values are little changed [36].
As the DRL is taken as the third quartile dose value, there is a reasonable
expectation that measurements averaged over a number of patients in any
institution will lie below it. If the dose is systematically above the DRL, it is12relatively easy to identify problems, if any, and to correct them without loss ofclinical information. For example, it might be the unnecessary use of a grid. It isalso possible that the dose may be too low, and corrective action in this regard, inpursuit of necessary improvements in image quality, may also be warranted.
The values shown in Table 2 are from surveys conducted in 1996 and for
5 year olds. Different values might be obtained with newer technology, better
techniques or newer dosimetry protocols, and with infants or 10 year olds. The
values and units used in this publication are those employed in the publications
cited. Some more up to date data for individual countries, involving newer
equipment, and with older and younger age groups, are available (see Section 4.2.2
and Appendix III). Some of these are used as local departmental, regional or
national reference values. However, more up to date EC or other international
DRLs have not been adopted. This is a significant deficit in the support system
necessary for optimization of protection and safety in paediatric radiology.
Reference doses for other techniques are presented in the appropriate parts ofSections 4–7.
Finally, it is necessary to be aware that achieving dose levels below the
DRL does not guarantee that optimization of protection and safety has beenachieved. For example, one hospital in the United Kingdom has achieved local
reference doses that are routinely 5–25 times less than the national DRLs. The
hospital attributes this to careful optimization of all of the equipment and

TABLE 2. THE EUROPEAN COMMISSION’S DIAGNOSTIC REFERENCELEVELS (STANDARD 5 YEAR OLDS) [35]Radiograph

Entrance surface
dose per image(μGy)

Chest PA100

Chest AP (for non-cooperative patients)

100

Chest lateral

200

Chest AP (newborn)

80

Skull PA/AP

1500

Skull lateral

1000

Pelvis AP

900

Pelvis AP (infants)

200

Abdomen AP/PA (with vertical/horizontal beam)

1000

Note: AP: antero-posterior; PA: postero-anterior.

13

technique steps in the imaging process [37]. Thus, while DRLs are useful, they
are not the only tool in the ‘optimization toolbox’ and the use of parallel
approaches to implementing optimization needs to continue.

2.4. DOSE LIMITS AND DOSE CONSTRAINTS FOR OCCUPATIONALLYEXPOSED WORKERS, CARERS AND COMFORTERS,AND MEMBERS OF THE PUBLIC
Occupational exposure of radiation workers in hospitals or dental practices istreated in depth elsewhere and will not be addressed in detail here [2, 38].
Nevertheless, the dose limits for occupationally exposed workers and the dose
limits for members of the public are provided in Table 3 [2]. In general, with goodpractice and good facilities, there will be no difficulty meeting the limits forworkers, even for interventional procedures and special procedures (Section 5).
However, in the absence of good practice or good facilities, there is some risk inthese areas. Advice is provided that will help workers deal with these situations.
With regard to exposure of members of the public, this will not normallyhappen during paediatric radiology. Relatives or friends of the child will beclassified as carers and comforters when they willingly and necessarily
accompany, comfort, restrain or care for a child during a diagnostic procedure.
Exposures received by them in these circumstances are classified as medical
exposures and are not subject to the dose limits for public exposure [2, 5, 12, 39].
This arises because there is a direct benefit, both to the patients and to those whocare for them.
Carers and comforters have to be provided with adequate information on
how to protect themselves and, where necessary, with appropriate protective
clothing and/or devices. Pregnant women are not to be allowed to assist in thisTABLE 3. DOSE LIMITS FOR OCCUPATIONALLY EXPOSED WORKERS
AND FOR MEMBERS OF THE PUBLIC [2]Type of limit

Occupational exposure

Public exposure

Effective dose

20 mSv per year

1 mSv per year

Lens of the eye

20 mSv

15 mSv

Skin

500 mSv

50 mSvHands and feet

500 mSv—

Annual equivalent dose to:Note: Some flexibility with regard to averaging over longer periods is allowed [2].

14

way. The BSS [2] treat the selection of constraints for carers and comforters as acomplex process in which it is required to take a number of factors into account,
including the possibility that the individual carer or comforter is pregnant.
Dose constraints are a valuable planning tool in this context. They are used
as an upper bound on the doses that individuals might expect to receive from aplanned procedure, such as comforting, caring for or assisting withimmobilization of a patient. An international consensus has not fully evolved on
appropriate values, but those in Table 4 have been recommended by both the
IAEA and the EC for those involved in a single episode of radio-iodine
therapy [40–42]. These values are not to be rigidly applied as a dose limit. They
may be exceeded where circumstances warrant it, for example, in the case of aparticularly serious illness or difficult intervention [12, 41].

2.5. UNNECESSARY EXPOSURES
Unnecessary radiation exposures of patients can arise from failures of
optimization or from errors. In paediatric radiology, these would include aradiological procedure performed on the wrong person, the wrong body partbeing subject to the exposure, the exposure being substantially greater than was
intended, or, in the case of an adolescent girl, the inadvertent exposure of anembryo or foetus. Such events need to be investigated to determine the doses
received and to determine and implement the corrective actions that are needed toprevent recurrence of the event. In some cases, such as for significant doses andas required under the law, the event would have to be reported to the regulatory
body [43]. In all cases, the patient and the referring medical practitioner have to
be informed [2].

TABLE 4. PROPOSED DOSE CONSTRAINTS FOR EXPOSURE FOR
FAMILY AND CLOSE FRIENDS AS CARERS AND COMFORTERS [40, 41]
AgeDose constraint (mSv)

Children (including unborn children)

1

Adults up to about 60 years old

3

Adults over 60 years old

15

15

2.6. SPECIAL CONSIDERATIONS ASSOCIATED WITH PREGNANCY
The general provisions of the BSS [2] and/or national legislation andprofessional codes of practice are required to be observed with respect topregnant or potentially pregnant, occupationally exposed workers, and exposureof carers and comforters, and members of the public. These will not be repeatedhere and the reader is referred to the standard literature in this area [44–46].
Pregnancy can occur in adolescent girls. Precautions for this group have tobe taken for exposures that may involve a foetus, and such exposures need to be
avoided where possible. In female adolescents who are menstruating, the ten day
rule needs to be considered when procedures with high exposures are involved,
such as examinations or interventions involving the abdomen, pelvis or uterus,
and in particular CT [45].
With this group, care and sensitivity have to be exercised with regard to thecircumstances in which they are asked the relevant questions, so as both torespect their privacy and to increase the likelihood of being told the truth. With
respect to pregnancy tests, many are of little value in excluding early pregnancy.
In the EU, pregnancy is assumed in females of childbearing age in whom
pregnancy cannot be explicitly excluded. If the requested examination isconsidered urgent, the referring clinician may override these concerns [45].

2.7. RESEARCH INVOLVING IRRADIATION OF CHILDREN
Biomedical research involving the use of ionizing radiation in children has
to be performed within the well established framework provided by national andinternational recommendations [2, 5, 14]. This generally includes the provisionthat the research be approved by an ethics committee or institutional review
board. The ethics committee or equivalent will generally include representativesof both institutional and public interests, who will consider the radiation benefits
and risks associated with the use of radiation in the proposed research as just one
part of their approval process. It is, therefore, essential that correct information ondoses, risks and benefits, with respect to the proposed exposures, be presented tothe ethics committee as part of the research proposal.
The use of repeated radiographs or CT scans to monitor progress in, forexample, drug trials can only be undertaken after much deliberation. The
examinations, where possible, have to be limited to essential scans or views. For
example, yearly full skeletal survey examinations may not be necessary tomonitor progress of therapies for Gaucher’s disease. The use of dose constraints
for exposures incurred as part of biomedical research is a practical means forradiation protection, and ethics committees need to specify such constraints in

16

granting their approval [2]. The detailed requirements are not addressed here but
attention is drawn to the special issues involved in irradiation of children.
Research is generally severely proscribed and is to be undertaken only when there
is no alternative.

2.8. EDUCATION AND TRAINING
The need for medical practitioners providing radiological services, and forother professions, including medical physicists and medical radiation
technologists, to undertake additional special education and training is wellrecognized and has been extensively discussed elsewhere [2–4, 12, 47, 48].
Formally recognized training in the radiological techniques involved and inradiation protection is required. Radiologists, medical physicists and medical
radiation technologists working with children need to have specific training in thespecial issues that arise in paediatric radiology, over and above their generalradiological training.
There is value in emphasizing the team approach to operational aspects ofradiation protection and dose reduction programmes. Once such practitioners aretrained, the need for continuing professional development in new techniques andtechnologies has to be recognized. The special needs for information and trainingof carers and comforters also have to be attended to in departmental training
programmes.
Training material in support of the above areas and many of the objectives
mentioned are available with free downloads of related presentations from the
IAEA’s Radiation Protection of Patients web site [20] and the Image Gently website [10].

173. CONSIDERATIONS IN EQUIPMENT PROCUREMENT
AND IMMOBILIZATION OF PATIENTS
Equipment used for paediatric radiology needs to be well designed andsuited for the purpose. This is best ensured by having a good procurement policythat includes rigorous specification of what is required and verification that this iswhat the supplier delivers (see Section 3.1). In addition, a quality assurance
programme is required to ensure that the equipment continues to be both
functional and safe throughout its service life (see Section 3.2). This underlines
the need to include medical physicists and quality assurance teams inprocurement.
These considerations are important in paediatric radiology, where special
steps are often necessary to ensure that exposure factors will be ‘child-sized’.
Where the same equipment is also used for adults, this can be a major problem.
However, it can also be problematic even where equipment is solely for
paediatric use. Equipment supplied with general purpose exposure protocols will
inevitably and systematically overexpose children. Care in procurement also
applies to ancillary items, for example, shielding for patients, lead aprons orprotective screens. Special arrangements to facilitate immobilization of children
are considered in Section 3.3.

3.1. EQUIPMENT PROCUREMENTRadiological equipment can be very expensive. For this reason and toensure safety, the procurement process followed has to be formalized [49]. It
needs to specify the functions that the equipment is expected to perform. It is also
important to ensure that equipment complies with appropriate international
technical standards, such as those developed by the International ElectrotechnicalCommission (IEC) [50–54]. The safety standards of the IAEA will apply [2–4].
Such standards establish requirements for the levels of safety and of performance
to be achieved. Taken together with manufacturers’ specifications, these will
ensure that the equipment purchased is appropriate, achieves the performance
expected and is safe.
More attention needs to be given to the development of technical standards
specifically for equipment intended for paediatric use. Examples of where thisarea has been neglected include automatic exposure control (AEC) systems inradiology and fluoroscopy, and the scanning protocols in CT. However, there arerecent encouraging signs that both the industry and technical standards
organizations recognize this and are open to suggestions for corrective actions. In

18

Europe, additional requirements are expected for all equipment, whether old or
new, to meet minimum criteria of acceptability for use with patients [5, 49].
Once installed, equipment needs to be acceptance tested so that its supply,
performance and safety are verified prior to commissioning for clinical use [49].
This is consistent with practice in some countries, where an agent (other than the
supplier) who acts for the end user and/or the hospital has to sign off acceptancetests [5, 49]. Even where this is not legally required, it is important that it is done
and properly documented. On installation, ‘child-sized’ exposure factors andprotocols have to be established and communicated to all relevant staff as part ofuser training. This is particularly important with angiographic and CT
systems [2, 49, 53–57].
The stages involved in the procurement process are listed in Table 5. All ofthese stages are important, regardless of the organizational framework in which
they occur. Neglecting them almost inevitably leads to problems. The advice andsupport of an experienced procurement officer is invaluable. When estimating
costs, the list in Table 6 may be considered. Where possible, these items need to
be included in the main contract for provision of the equipment. Otherwise, many
will be neglected and they are difficult to resource once the equipment has beendelivered and paid for.
When second-hand equipment is considered, it needs to maintain theoriginal manufacturer’s specifications and meet the local minimum criteria for
acceptability. Proof of compliance with these requirements has to be obtained. If
an original feature is no longer functional but the equipment still meets thecriteria for acceptability, this has to be clearly indicated in the documentation
provided by the donor and/or seller [58].
In addition to the technical considerations, other operational, training andmaintenance requirements have to be met. Satisfactory operator training isessential for all systems but particularly for CT, fluoroscopy and digital systems.

TABLE 5. STAGES OF THE PROCUREMENT PROCESS
Analysis of equipment requirements (clinical and technical)
Development of equipment specifications
Invitations to tender to appropriate suppliers
Analysis of tenders
Agreement of contract
Installation of equipment
Acceptance testing, commissioning and acceptability testingOn-site application training

19

TABLE 6. ITEMS TO BE INCLUDED IN THE COSTS OF A RADIOLOGYFACILITY
Purchase and installation of the radiology equipment
Building costs, including structural shielding
Provision of alternative services during refitting (where relevant)Radiation protection devices, including the operator’s protective lead screen, ceiling suspended
lead screens, lead screens at the tableside, lead aprons, etc.
Ancillary equipment and/or accessories, including film processors, laser imagers, printers,cassettes, etc.
Test equipment for quality assurance
Ongoing running, maintenance, acceptance testing and quality control costs
Operator training and continuing education

The absence of such machine specific application training leads to systematic
overdosing of patients and unnecessary exposure of staff over prolonged periods,
sometimes several years. It is also important to budget for acceptance testing andongoing quality control testing, particularly if this is to be carried out by third
parties.

3.2. QUALITY ASSURANCE OF EQUIPMENT
A quality assurance programme in diagnostic imaging ensures quality
during all phases of the operation of the service. One aspect of such programmes
focuses on the operation of equipment. Quality assurance is required by the BSS,
by many governments and the EC, and is recommended by numerous
professional bodies [2, 49, 57, 59–61]. A quality assurance programme may beseen as part of clinical audit and part of the optimization process. It is important
to ensure that equipment is working properly, is delivering the exposures
expected and is compliant with good standards of installation and design.
Examples of relevant tests with a general radiography unit include checking
whether the X ray beam is coincident with the light beam localization system,
what its output is and whether the correct filters are present. Accurate, well
adjusted collimation is essential in paediatric radiology because of the small sizeand close proximity of a child’s organs. It is essential that the results from quality
control assessments be integrated into the work of the management of thedepartment, so that the findings are noted and acted on. A wide range of
published guidelines are available for quality assurance [59–61].

20

3.3. CONSIDERATIONS IN IMMOBILIZATION
Immobilization is required with many children when performing
radiographic studies. This is required so that:— The beam can be correctly centred.
— Correct collimation can be obtained.
— Blurring and motion artefacts are reduced.
— The non-examined parts of the body are properly shielded.
Devices, such as sponges, sandbags or polymethyl-methacrylate plates,
may be used with very small infants. In young children, it may be useful to takeadvantage of the period when the infant is calm or asleep after being fed toperform the radiological examination. With longer or more complex
examinations, some sedation may prove valuable or necessary.
When assistance of a person is required for immobilization of or comfortinga patient, this is, generally, not to be done by radiological or hospital staff. If,
exceptionally, hospital personnel help in this way, the exposure they receive isconsidered an occupational exposure [2] and care has to be taken to ensure thatthe same staff members are not repeatedly exposed.
It is preferable that the patient be comforted or restrained by parents or
relatives. In this case, the doses received are classified as doses to carers andcomforters, and are dealt with as outlined in Section 2.4. This is the more
appropriate route to follow as it avoids repeated exposure of the same hospital
staff. It requires that the duties involved be undertaken by people who know therisks and that appropriate provision be made for informing them and protecting
them (e.g. use of lead aprons). Those for whom pregnancy cannot be excluded
will not be allowed to act as carers and comforters.
Even for young children, the time allocation for the examination has toinclude the time necessary to explain the procedure, not just to the accompanying
parent or person but also to the child. Information specifically adapted for theparent and the child can be forwarded to the family in advance of the study. Video
recordings or illustrated books and materials provided for viewing by children in
the department in advance of the studies can also be helpful. Time taken to
explain to a child and the parents what will happen is time well spent in obtaining
optimal cooperation and securing a good examination [61].

21

4. GENERAL RADIOLOGY
The wide range of activities that constitute general radiology are consideredin this section. They include film screen radiography, which was the staple of the
field until recently. The subset of radiography practised with mobile equipment
and the conditions under which it is appropriate to use such systems are also
considered. Dental radiography is a special case and is briefly reviewed in
Section 4.3. In all cases, radiography is now commonly practised using digital
receptors to replace films and screens. The more widely used receptors incomputed radiography (CR) and direct digital radiography (DR) are considered in
Section 4.2.4. The section starts with a discussion of justification and theparticular concerns it raises in paediatric radiology.

4.1. JUSTIFICATION IN FILM SCREEN RADIOGRAPHY,COMPUTED RADIOGRAPHY AND DIGITAL RADIOGRAPHY
As emphasized in Section 2.2, all radiographic examinations are required tobe justified [2]. This gives rise to particular considerations in paediatricradiology. When doubt arises about whether or not a procedure is justified, thefinal decision will be made through consultation between the appropriately
trained and/or experienced radiological medical practitioner and the referring
medical practitioner, as appropriate. In this context, it is important to ask thereferring practitioner, the patient and/or the family about previous procedures.
Examples of examinations which are often requested but which
experienced paediatric radiologists will generally not advise as routinely
indicated are listed in Table 7. In dealing with any request for an examination, it
is important to consider the clinical history, previous examinations and theavailability of alternative modalities that do not use ionizing radiation.
Excellent tools have been developed to assist in justification. They include
referral or appropriateness guidelines for radiological examinations, such as thosedeveloped by various bodies [17, 28–30]. In these, a marker for the strength of theevidence base on which recommendations are made is provided. An updated
version of the 2001 EC referral guidelines for paediatric radiology was publishedby the EC in 2008 and is reproduced in Appendix II [28, 29].
The guidelines are advisory rather than mandatory, and how they areapplied may have evolved since their publication. They were developed for
conditions that prevailed in Europe [62] at the time of publication and will need
to be adapted to any specific circumstances to take due account of place and time.
The issuing of a further revised set of guidelines is being planned by the EC.

22

TABLE 7. JUSTIFICATION PROCESS AND EXAMPLES OF EXAMINATIONSNOT ROUTINELY INDICATED
Justification
Justification is required for all radiographic studies.
The referring practitioner, patient and/or family need to be asked about previous procedures.
Referral guidelines need to be used where appropriate and available.
Alternative approaches, such as ultrasound or MRI, need to be used where appropriate.
Information needs to be provided to the patient in accordance with the BSS [2] or national standards.
Justification needs to be included in clinical audit.
Examples of examinations not routinely indicated
Skull radiograph in a child with epilepsy.
Skull radiograph in a child with headaches.
Sinus radiograph in a child, under 5 years of age, suspected of having sinusitis.
Cervical spine radiograph in a child with torticollis without trauma.
Radiographs of the opposite side for comparison in limb injury.
Abdominal radiographs in children with constipation.
Scaphoid radiographs in children under 6 years of age.

Similar recommendations are available in Canada, the United Kingdom, the USA
and elsewhere, but can be difficult to access freely outside the professional bodies
involved [15, 17, 30, 31]. There is much variability in the extent to which thesetools are implemented in practice.
One of the more important ways of enhancing the justification process isthrough audit of referral patterns. In general radiology with adults, recent datasuggest that 20–40% of examinations could be avoided if clinical decision
guidelines were followed [63]. Use of guidelines has a significant impact on this,and with appropriate management, sustainable reductions in exposures can beachieved [5, 17, 33]. There is every reason to expect that guidelines and audit
could be similarly effective in paediatric radiology. Thus, there is a compellingcase for the wider use of both guidelines and audits.
For most purposes, the justification process followed for generalradiography can be applied without much variation for CR and DR. The intent
and outcome of the examinations is similar, and the major differences arevariations in and the selectability of image quality and dose. These may need tobe taken into account in the justification process in due course.

23

4.2. OPTIMIZATION AND GENERAL RADIOGRAPHY
4.2.1.

Optimization in film screen radiography

Once exposures have been justified, protection and safety are required to be
optimized [2]. A practical set of techniques for reduction of exposure andoptimization of protection and safety in general paediatric radiography isprovided in Table 8. This set is similar to the techniques used for radiography ingeneral. However, there are special issues in paediatric radiology that need
concerted attention.
One of these is the approach to manual exposure and AEC selection. In thelate 1990s, 94% of exposures in paediatric radiography were performed using
manual techniques, a much larger proportion than with adults [64]. This practice
has to continue until such time as manufacturers provide AEC facilities and/or
software based protocols for exposure that are appropriate for paediatric use.
Currently installed AEC technology is generally not appropriate for children as
the sensor size, geometry and software are normally designed or set up for adults.
Pending developments in design and in technical standards, it is, thus,
preferable to use exposure charts specific to the radiographic technique, thepatient’s size and weight, and the presence or absence of a grid. Developments in
exposure sensors and related software, and their intelligent application in
paediatric radiology, are a significant challenge for the industry, standardization
bodies and hospital staff. Considerable improvement could be achieved in thisarea with concerted cooperation.
It is important to have a standard type and number of projections for
specific indications. Views in addition to the standard ones may only be
performed on a case by case basis. For example, comparison radiographs inchildren for the assessment of trauma are not routinely necessary. It is also
important, in practice, to consider the indication for the study. For example, in an
intensive care setting, lines and catheters are inherently high contrast and there issignificant opportunity for dose reduction when the clinical indication for a study
is solely to confirm their position.
Beam output, filtration and focal spot size need to be known, to beappropriate for the application, and to be within acceptable limits [49, 59]. Doses
can generally be reduced by using additional beam filtration and higher X ray
tube voltage (kVp), but at some cost to contrast. Reliable, well managed film
processing is essential. Use of fast film–screen combinations is possible for mostradiography and allows a significant reduction in dose and exposure time [65].
The consequent reduction in resolution that is possible is insignificant for the
majority of clinical indications.

24

TABLE 8. TECHNIQUES FOR REDUCTION OF EXPOSURE AND
OPTIMIZATION OF PROTECTION AND SAFETY IN GENERAL RADIOGRAPHY
There needs to be a standard type and number of projections for specific indications.
Views in addition to standard may only be performed on a case by case basis.
Manual technique selection needs to be used pending equipment developments.
Where practical, a long (or the recommended) focal to skin distance needs to be used.
The X ray beam needs to be carefully collimated to the area of interest, excluding other regions,especially gonads, breast, thyroid and eyes.
Appropriate gonad, thyroid, ovary and breast shielding needs to be used.
Fast film screen combinations are acceptable for the majority of indications.
It needs to be ensured that film processing is working well.
An anti-scatter grid need not normally be used.
Postero-anterior projections need to be used, where practical, for radiographs of chest and spine.
It needs to be ensured that the correct filtration is used to reduce entrance surface dose.
As high an X ray tube voltage as is consistent with the examination requirements needs to be used.
Additional filtration at higher X ray tube voltage needs to be considered.
The use of a small focal spot size and short exposure times need to be balanced.
Quality assurance and audit programmes need to be used for all aspects of the department’s
work, including film processing.
A system needs to be introduced and used that allows patient dose to be assessed regularly.

Anti-scatter grids are normally not necessary because of the smaller size ofchildren. Anti-scatter grids are usually not advisable for abdominal examinations
in patients under 3 years of age or for skull radiographs on patients younger than
1 year old. Not using them avoids unnecessary exposure and results in an
approximately 50% reduction in dose [65].
The use of postero-anterior projections, where possible, in performing
radiographs of the chest and spine reduces breast dose but may not always bepractical in smaller children who cannot fully cooperate. A system for periodic
assessment of doses to the patient is needed, and this then enables comparisons to
be made with relevant DRLs (see Section 4.2.2). This can become part of thesystem of quality assurance for medical exposures in the facility.
The beam has to be reliably collimated to the area of interest so that otherregions are excluded. Accurate well adjusted collimation that is closely alignedwith the light beam diaphragm is essential because of the small size and close
proximity of a child’s organs. In practice, it is not uncommon to see radiographswith wide open collimation. This practice is unacceptable and is a significant

25contributor of avoidable doses. Additional shielding can be important for dose
reduction. Gonad and breast shielding reduce the dose to these organs [66].
Each of these measures contributes systematic dose savings that often range
from a factor of two to ten, with the result that their combined effect candramatically reduce dose. Once good practice is established, it is important tosustain it through a quality assurance and constancy checking programme. This isparticularly so for film processing. The advice on dose reduction presented hereis based on that from the third ‘ALARA’ conference organized by the Society for
Paediatric Radiology [67].
4.2.2.

Doses and reference values for plain film radiography

A valuable tool in the optimization of protection and safety is comparisonof the doses employed in a department with DRLs (see Section 2.3.1). The EC
has proposed a set of DRLs for common radiographic projections (see Table 2).
These DRL values are for 5 year olds and different values would beobtained for older or younger children. However, it is felt that providing resultsfor even one group may act as a marker for a department’s performance. Some
additional data for these older and younger age groups, from three EC paediatrictrials conducted in 1989–1991, 1992 and 1994–1995, are presented in Table 9 but
DRLs drawing on these have not been adopted to date [62]. However, the large
ratio of the maximum to the minimum values seen ranges from about 30 to almost
100, and indicates the room available for improvement through optimization.
DRLs are not dose limits but are, rather, intended as advisory action levels, which
will trigger an investigation if exceeded (see Section 2.3.1).
Tables 2 [35] and 9 are taken from an EC publication of 1996. These tables
are based upon practice prior to the heightened awareness of dosage in paediatricradiology and before CR and/or DR and exposure selection technology became
dominant in some parts of the world. Hence, while they provide a useful upperbound, they need to be re-evaluated to take into account the developments in thepast decade and a half.
In the meantime, most departments need to be able to achieve these levels.
The United Kingdom Health Protection Agency reports that the dose at whichreference levels might reasonably be set for adults have been reduced by a factor
of at least two in general radiography since they started monitoring the area overtwo decades ago [68]. It is reasonable to assume that a similar level of attention to
paediatric radiology might have a similar impact.

26

27

588

56–2917

1:52

Note: AP: antero-posterior; PA: postero-anterior.

729

2427

Lumbar spine lateral

Abdomen AP/PA

1629
1146

Lumbar spine AP
1:42

812

577

1036

153

91

71

MedianThoracic spine lateral

77–3210

1:32

1:17

1:19

1:15

1:11

1:71

Minimum:
maximum

887

440

86–2785

138–2358

242–4626

37–55429–333

19–1347

Minimum–
maximum

5 year old

Thoracic spine AP

1:41

867

Full spine PA/AP

107–4351

703
1:76

485

18–1369260

Pelvis AP

1:30

67
68

Skull lateral

152–4514

1:47
1:21
967

930

21–97934–718MedianSkull PA/AP

Chest AP (mobile)

1:35

Minimum:
maximum

140

75
90

Chest PA/AP

11–386

Minimum–
maximum

InfantChest lateral

45

MedianChest AP
(1000 g newborn)

Examination type148–3981

249–23 465

131–5685

303–6660

204–4312

89–4167

113–3787

130–5210

39–1976

29–760

17–1157

Minimum–
maximum

10 year old

1:27

1:94

1:43

1:22

1:21

1:47

1:33

1:40

1:51

1:26

1:68

Minimum:
maximum

TABLE 9. VARIATIONS IN ENTRANCE SURFACE DOSE (µGy) IN EUROPEAN COMMISSION PAEDIATRIC TRIALS(median, minimum–maximum values and corresponding ratio (minimum:maximum) [62])TABLE 10. ENTRANCE SURFACE DOSE PER
RADIOGRAPH FOR DIFFERENT EXAMINATIONS
AND AGES [1]Examination

Age (a)Mean entrance surface dose(µGy)

Abdomen AP

0
1
5
10
15

110
340
590
860
2010

Chest AP/PA

0
1
5
10
15

60
80
110
70
110

Pelvis AP

0
1
5
10
15

170
350
510
650
1300

Skull AP

1
5

600
1250

Skull lateral

1
5

340
580

Note: AP: antero-posterior; PA: postero-anterior.

Additional tables for the mean ESD for paediatric patients are provided fora limited number of projections in a range of age groups. The United Kingdom
study (Table 10), also noted by UNSCEAR, is of value because it is more recent
than the EC study [1]. The data from the Madrid study [69] are reported inTable 11 on CR and are cited in Section 4.2.4. The age cohorts and the
projections are not exactly equivalent in the tables.
Notwithstanding this limitation, the data will be useful to those taking steps
for optimization of protection and safety in their practice. A recent Bulgarian
study compared the values with the EC DRLs where a large spread in values
continues to be present [70]. The authors attribute this to a number of identifiable
causes including widespread use of grids, use of low kVp values and, in someexaminations, use of low speed film–screen combinations.

28

TABLE 11. COMPUTED RADIOGRAPHY MEDIAN ENTRANCE SURFACEDOSE FOR VARIOUS EXAMINATIONS AND AGE GROUPS [1]Examination

Age range (a)Sample size

Mean entrance surface dose (µGy)

Chest (no bucky)

0–1
1–5
6–10
11–15

1180
309
143
92

41
34
54
10

Chest (bucky)

1–5
6–10
11–15

181
255
363

87
105
170

Abdomen

0–1
1–5
6–10
10–15

93
30
69
150

91
225
600
1508

Pelvis

0–1
1–5
6–10
11–15

254
128
122
137

48
314
702
1595

As noted in Section 2.3.1, DRLs may wrongly suggest that the optimization
process is complete; continued attention to parallel means for optimization isnecessary.
A survey from the EC SENTINEL Project of European paediatric doses ingeneral radiography provides a wide range of information that is difficult tosummarize, and some recommendations in respect of DRLs for both entrance
doses and dose–area product values [71]. In the current international code ofpractice, dose–area product is now called kerma area product (KAP) [36]. Thissuggests that, in some countries, the aspiration to meet the EC DRLs is not being
achieved. Additional data on these studies and others are presented inAppendix III. From the above, it is evident that there is a serious lack of current
data for all forms of paediatric radiography in respect of one of the key markers
for optimization, i.e. evidence based DRLs. It is essential that this be corrected.
4.2.3.

Mobile radiography

Mobile radiography is valuable when it is impossible for the patient to cometo the radiology department. However, it results in poorer quality images and cangive rise to unnecessary exposures of staff and patients. For example, it is not29uncommon to find that inferior radiographs taken with a mobile unit need to berepeated on a fixed unit the next day, thereby increasing patient exposure. Thus, it
is more difficult to warrant the use of mobile radiography when the alternative ofa fixed unit is available. To minimize the problems involved, it is now widely
accepted that, where practicable, X ray examinations need to be carried out with
fixed units in an imaging department. Mobile units need to be used only for those
who cannot safely be moved to such a fixed unit.
The principles outlined above for optimization in general radiography alsoneed to be followed with mobile radiography, as far as it is practicable to do so. In
addition, routine use may be made of portable lead shielding to protect nearby
patients. The advice of the medical physicist and/or RPO needs to be obtained on
how best to do this. For example, the risk may be minimal in an intensive careunit for newborns, where there is considerable space between the incubators.
Tiny infants weighing as little as 500–600 g can be radiographed using very low
exposure and there is very little scattered radiation.
4.2.4.

Optimization with computed radiography and digital radiography

Film–screen radiography is now being superseded by a variety of digitaltechnologies in many countries. In some western countries, this transition has
been ongoing for over a decade and is now virtually complete. While several
digital options are available, the most widely deployed are CR and DR, also
sometimes known as direct DR [72, 73].
The most important distinction between the two is that CR involves anintermediate step in which the image is stored as a latent optical image, in a
cassette-like device, before it is converted to electronic digital form, using laser
technology. With DR, on the other hand, the image is created immediately inelectronic digital form, in the image receptor. Images from both systems can bedisplayed on suitable high resolution monitors but in practice they are often
printed out on film, particularly when resolution is a concern.
One of the driving forces in DR has been the possibility, indeed thepromise, of significant dose reduction without loss of necessary image quality.
The key factors in creating these possibilities include greatly improved contrast
resolution, accompanied by almost infinite possibilities of processing the image
after acquisition, with a view to improving the features eventually displayed.
However, the improvement in image quality often results in higher patient dose,
and the tendency to use higher patient doses than are necessary needs to be
avoided [74].
Clinical and phantom studies have been performed by comparing radiationdose, image quality and diagnostic accuracy of film–screen and hard and soft
copy digital chest radiography [75–78]. Using the EC (1996) quality criteria as a30

semi-objective means of assessing image quality in chest radiography in children,
Hufton et al. were able to demonstrate a dose benefit of 33% for CR comparedwith analogue chest radiography with a film speed of 400 [79]. Many otherstudies have also demonstrated potential benefits in terms of reduced dose withboth CR and DR systems [72, 80, 81]. For example, a Spanish study found that an
exposure reduction by a factor of 2.5 was consistent with images of sufficientquality to maintain the standards set by the EC [69, 82].
However, in spite of this success, a note of caution has to be raised. In
general, digital imaging has the potential for dose reduction while improving
image quality and diagnostic accuracy — but only with much attention to staff
training and careful, continuous monitoring of departmental parameters andpractices. The key issue is that, with image processing, the image quality willcontinue to look good even if the dose increases well beyond that required for an
acceptable image. This removes one of the warning signs that, inadvertently, areprovided by film–screen technology [83, 84]. On the other hand, with digitalsystems, dose cannot be reduced indefinitely as increased electronic noise
reduces image quality. In practice, there is a tendency among technologists toavoid the need for repeats by erring on the side of overexposure [84].
Appropriate image processing is, therefore, crucial for optimization in
producing a paediatric CR or DR image. To date, there is little standardization in
the methods of image processing or their nomenclature. Practitioners are facedwith the choice of accepting the supplier’s default processing options orundertaking the arduous ‘trial and error’ task of customizing the processing fortheir local conditions.
In view of all of the above, it is important that radiology departments
prepare well for the introduction of digital technology or for a new system
involving digital technology. In the first instance, this needs to involve in-depth
staff training on the specific system to be introduced. Generic training on digitalsystems, while helpful, is not adequate as there are significant operational
differences between suppliers. Well trained staff need to adopt a team approach,in cooperation with the suppliers, technical staff, the hospital’s medical physicist
and maintenance staff, to identify and maintain suitable exposure parameterswhen a new digital system is installed. In addition, a good, practical, wellintegrated quality assurance programme is essential.
Exposure index (EI), which provides a method of monitoring dose, is anindicator of the radiation incident on the imaging plate, something which isessential. As illustrated in Table 12, different manufacturers have developed
different indices [72]. Some of these can be confusing or misleading for end users
as the index may be counter-intuitive (i.e. it increases when the dose required
decreases).

31

TABLE 12. EXPOSURE INDICES FOR THREE MANUFACTURERS’DIGITAL SYSTEMS (adapted from Ref. [72])Manufacturer

Exposure
index

Unit

Mean receptor exposure
5 µGy

10 µGy20 µGy

1.9

2.2

2.5

Agfa

lgM

bels

Fuji

S

No units

400

200

100

Kodak

EI

mbels

1700

2000

2300

By correlating ESD with the EI, a range of acceptable values for specificclinical indications for optimization can be obtained. Unfortunately, although the
EI may appear on the image processing workstation and on hard copy
radiographs, it may not transfer to the patient record and/or archive. The different
forms of EI used and the problems of interconnection are standardization
problems. Significant developments are being achieved in this area, and it isexpected that there will be notable improvements in the next generation ofequipment [85].
Further developments in equipment may also contribute to possibilities ofdose reduction. These include development of completely innovativetechnologies, such as approaches based on slit scanning [86]. In a 2008 study, thissystem demonstrated very large dose reductions for skull, spine, pelvis andabdomen, and more modest gains for chest. However, it remains to be seen
whether these are sustainable. Beyond these dramatic developments, most CR
and DR manufacturers, recognizing that paediatric patients are different, havedeveloped or are developing special provisions for paediatric examinations,
including image processing.
In addition, it is essential that paediatric radiology undergo somestandardization, and this requires commitment from end users, organizations
setting technical standards and manufacturers. The importance of a continuous
effort in this regard cannot be overemphasized, as it can lead to significant
systemic dose reductions. The possibilities parallel the well established dosesavings achieved by fast film–screen combinations in traditional radiology
departments or dual readout CR technology, each of which, on the basis of aone-off initiative, can offer reductions in exposure in the range of 50% [87, 88].
However, while these possibilities are real, in practice there is a risk that patient
doses will increase where digital technology continues to be introduced withinadequate preparation [89].
The recommendations given in Table 13 are designed to aid dose
reduction and image management for optimization with DR and CR. The tablerelies on transfer of many of the practices that provide for good general

32

TABLE 13. DOSE REDUCTION FOR END USERS AND MANUFACTURERS
OF COMPUTED RADIOGRAPHY AND DIGITAL RADIOGRAPHYEQUIPMENT
Dose reduction for end users
Justification is required for computed radiography and digital radiography studies as it is forgeneral radiography.
Positioning, collimation and selection of exposure factors, etc. are as essential for optimization
as in conventional radiography. A team approach to dose management is essential.
Team participants may include: a radiologist, medical physicist, medical radiation technologist,
clinical engineer from the hospital; and a service engineer, application specialist and imaging
scientist from the manufacturer.
Training of the radiologist and medical radiation technologist in the specific operationalfeatures of the computed radiography and digital radiography system in use is essential.
Dose reduction for manufacturers of computed radiography and digital radiography equipment
Manufacturers need to provide adequate end user training as part of the equipment supply
package.
Nomenclature for digital imaging processing algorithms and exposure indices needs to be
standardized.
Dose assessment is absolutely necessary for successful dose saving programmes. It is, thus,
essential to standardize exposure indices.
It is essential to make provision for passing the information on exposures and doses from theradiological equipment to the picture archiving and communication system and/or the patient
record in an accessible form [56, 81].
Dose measuring devices and dose indicators need to be calibrated and need to be protected fromcasual modification by the operator.
Manufacturers need to provide comprehensive training and guidance for the user on theirversion of exposure index or equivalent.
Manufacturers and organizations setting technical standards need to give particular attention to
the special issues of paediatric radiology.

radiography, such as positioning, collimation, appropriate filtration and selectionof suitable exposure factors (see Table 8). Recommendations directed topractitioners and the industry are included.

4.3. DENTAL RADIOGRAPHY
Much of intra-oral dental radiography, as in general radiography, involves
capturing a two dimensional projected image of radiation distribution.

33

Furthermore, a wide range of digital facilities are now available for dental
purposes although analogue film processing continues to be used. However,dental radiography normally involves a different group of professionals: dentists
and dental assistants. It is addressed here briefly for completeness, and the reader
is referred to the dental radiology literature for a fuller discussion [90].
4.3.1.

Justification in dental radiography

Radiation protection in dental radiography, as with general radiography,
begins with justification of the exposure. This may be seen as problematic where
there is a tradition of routinely radiographing all patients. In addition, in dentistry,
the referring medical practitioner and the radiological medical practitioner are
frequently the same person. In other areas of practice, there is much criticism of
this situation as it is regarded as leading to a form of ‘self-referral’ which resultsin systematic overutilization.
The absence of a tradition of well developed, evidence based guidelines forjustification that have a high level of consensus among dentists is a further
problem. Under normal circumstances, the risk from dental radiography is very
low. Nevertheless, it is essential that all dental radiographic examinations have aclinical justification and show a net benefit to the patient. This is particularly truein the case of cephalometric radiography and orthopantomographic examinations.
Table 14 summarizes guidelines that have been developed by the EC, and thefollowing text also draws on this [90].
Obtaining bitewing radiographs for caries diagnosis needs to be based on arisk assessment. Intervals between subsequent bitewing examinations need to bereassessed on each occasion, as individuals move into and out of caries risk
categories over time. In high caries risk children, there is good evidence tosupport taking posterior bitewing radiographs at the initial examination, even in
the absence of clinically detectable decay. Where a child is classified as being athigh caries risk, a subsequent bitewing examination may be made after six
months. Radiographs ought not to be taken more frequently than this and it isimportant to reassess caries risk.
Evidence of no new or active lesions is an indication that the child hasentered a moderate or low risk category. It is recommended that when children
are designated as having moderate caries risk that they may have annual posterior
bitewing radiographs. This may continue until no new or active lesions areapparent and the child has entered a low risk category. Radiographs for caries
diagnosis in low caries risk children need to take into account the population
prevalence of caries. Intervals of 12–18 months (deciduous dentition) and24 months (permanent dentition) are appropriate, although longer intervals may
be appropriate where the risk continues to be low.

34

TABLE 14. GUIDELINES TO FACILITATE JUSTIFICATION IN DENTAL
RADIOGRAPHY [90]All X ray examinations need to be justified on an individual basis. Anticipated benefits may
include new information to aid patient management.
Referrals for radiography to hospitals or other dentists need to be accompanied by sufficient
clinical information to permit the new practitioner taking clinical responsibility for justificationof the examination.
No radiographs ought to be performed without obtaining a history and conducting a clinicalexamination.
Routine radiography of all patients in particular categories is unacceptable.
Obtaining bitewing radiographs for caries diagnosis needs to be based on a caries risk
assessment.
Careful consideration needs to be given to the radiographic requirements for orthodontic
treatment.
Careful consideration needs to be given to any requirement for cephalometric radiography.
Cross-sectional tomography and CT in children ought to be used rarely and only after rigorous
justification with a view to answering specific clinical question(s).

When orthodontic treatment is required, most children are appropriately
treated at approximately 12–13 years of age and require radiographs to confirm
the presence and condition of all of the teeth. The radiographic examination will
frequently include a panoramic or right and left oblique lateral radiographs.
Upper anterior occlusal films are required to supplement the oblique lateralradiographs but not the panoramic study. Limiting the field size to the area
required for diagnosis is important for panoramic radiography.
Cephalometric radiography may be required in very specific circumstances,such as to assess the third molar or the position of the lower incisors at the end oftreatment with a functional appliance, and it needs to be performed only if theinformation is going to change the orthodontist’s decision on treatment. Where
possible, lateral cephalograms need to be collimated to limit the field to the area
required for diagnosis.
Newer techniques, including CT based systems, are finding significant
application in dental practice and are considered in the CT section (Section 6.4).
4.3.2.

Optimization in dental radiography

The considerations already mentioned in Section 3 in connection withprocurement, management and quality assurance for equipment hold, withappropriate adjustment, for dental radiography. The principal adjustments arise

35

from the fact that the equipment is less expensive, and that both the output and theworkload are lower.
Notwithstanding this, significant accidents can and do happen even withnew dental equipment [18]. The tradition of quality assurance is less welldeveloped and protocols for some equipment types, such as orthopantomograms,
need further work. In addition, there is a need for careful consideration of what
may be achieved in remotely based quality assurance programmes, without sightof the equipment or the circumstances in which it is housed.
Practical advice usually offered for intra-oral dental radiography equipment
is summarized in Table 15. Intra-oral DR offers a potential for further dose
reduction, subject to the considerations raised in the section on CR and DR
above. Additional literature on the quality assurance and performance levels
necessary to ensure dose reduction with digital dental systems is, however,scarce.
In the absence of more fully developed paediatric guidelines, more detailed
advice from adult practices will, for the present, have to be taken and suitably
adapted for paediatric use from publications such as EC 136 [90]. However, thenational reference dose of 1.5 mGy introduced in the United Kingdom for
paediatric intra-oral radiography provides a useful benchmark [91]. DRLs of
60 mGy · mm for the dose–width product and 82 mGy/cm2 for the KAP per
radiograph for panoramic views are also recommended.

TABLE 15. GUIDELINES TO FACILITATE OPTIMIZATION OF PROTECTION
AND SAFETY IN DENTAL RADIOGRAPHY [90]Only equipment adequate to meet current standards is to be employed for paediatric dental
radiography.
Optimal recommended X ray tube voltage for dental radiography is subject to some debate but
60–70 kVp is considered reasonable in terms of limiting entrance surface dose and generalefficacy.
Short cone collimators ought not to be used.
Long collimators are an effective means of dose reduction and ought to be used.
Use of film holding devices may be considered.
Where use of film holders is not possible or practicable, rectangular collimation (which is now
advised in both the United Kingdom and the USA) needs to be considered.
The fastest widely available films (F speed) will significantly reduce dose and ought to be used.
Intra-oral digital radiography offers the potential for further dose reduction; a reference dose of
1.5 mGy has been introduced in the United Kingdom.

36

It should be noted that there is a tradition in some areas of dental practice ofproviding protection over and above that which is strictly necessary, even where
there is no evidence to require its use on technical grounds. For example, withgood practice, there is no evidence of a requirement for gonad lead apron
protection with general dental radiography. Lead shielding of the thyroid gland
may be used in those cases where the thyroid is in the line of, or very close to, theprimary beam. This advice is based on the assumption that good practice withgood equipment prevails. Where this assumption might not be warranted, a goodcase can be made for continuing practices that may appear unduly cautious.

37

5. FLUOROSCOPY, FLUOROGRAPHY
AND INTERVENTIONS
Fluoroscopic procedures may be classified into two broad types. Long
established investigations, for example, gastrointestinal contrast studies, areconsidered in Section 5.1. Newer interventional and more sophisticateddiagnostic procedures are addressed in Section 5.2. These often require higher
doses and frequently involve using purpose designed equipment whose
operational modes are not always clear to the end user. The risk of high doses topatients and staff is much greater with these procedures, although this risk isbalanced by a therapeutic benefit. Increased awareness of the doses and risks
from medical irradiation of children has led to the Image Gently Campaign [10].
Sections 5.3 and 5.4 deal with doses to patients and to staff.
The terms ‘fluoroscopy’ and ‘fluorography’ are not precise. ‘Fluoroscopy’
denotes procedures such as gastrointestinal studies involving contrast media, orother dynamic studies involving real-time visualization of macroscopic
movement of anatomic and/or vascular structures using frame rates typical of
those obtained in video systems. The dose rates used in fluoroscopy are
categorized and regulated in many countries, with ‘high’ and ‘low’ doses
allowed.
‘Fluorography’ denotes the capture of discrete images from an imaging
chain and/or digital system, generally at lower frame rates and higher dose ordose rates than in fluoroscopy. For example, the frame rate might be 1 frame/s.
The image quality is generally high and the images may be used for the final
record. In cardiology, digital fluorography may replace cinefluorography at
relatively high frame rates.

5.1. CONVENTIONAL FLUOROSCOPY
Safety issues for a range of techniques, such as micturating cystograms andgastrointestinal contrast studies, are treated in conventional fluoroscopy. These
are generally well established techniques that are undertaken with well tested
protocols and with equipment whose design and purpose are well accepted andunderstood.
5.1.1.

Justification in conventional fluoroscopy

As with general radiography, it is required that all fluoroscopic
examinations for infants and children be justified. The general points raised in38Sections 2 and 4 are repeated and summarized in Table 16. It is important to ask
the referring practitioner, the patient and/or the family about previous procedures.
Where doubt arises about the procedure, the final decision needs to be taken by anexperienced radiological practitioner, where possible in consultation with thereferring medical practitioner. Examples of examinations that are not routinely
indicated5 are also listed in Table 16.
At a more formal evidence based level, tools with a structured evidential
approach which can assist the justification process are available. These include
the referral guidelines developed by the EC, which are reproduced withpermission in Appendix II [28, 29]. Other guidelines with a similar intent are alsoavailable [30, 31]. While these criteria are helpful, they are advisory and they
were developed for conditions that prevail in Europe. They may need to beadapted to take account of changes in appropriateness with changes in place andtime. In particular, the EC guidelines are a revision of a set originally developedin 2001 and issued in 2008, pending an update which is presently being
considered. Notwithstanding this, they provide helpful advice on when it isappropriate to undertake an examination and what the alternatives are. As pointed
TABLE 16. JUSTIFICATION IN FLUOROSCOPY AND EXAMPLES OF
EXAMINATIONS NOT ROUTINELY INDICATED
Justification
Justification is required for fluoroscopy studies.
The referring practitioner, patient and/or family need to be asked about previous procedures.
Referral guidelines need to be used where appropriate.
Alternative approaches, such as ultrasound or MRI, need to be used where appropriate.
Information needs to be provided to the patient in accordance with the BSS or national
standards.
Justification needs to be included in clinical audit.
Examples of fluoroscopy examinations not routinely indicatedUpper gastrointestinal contrast studies of pyloric stenosis.
Upper gastrointestinal contrast studies of children with recurrent vomiting.
Contrast enema in a child with rectal bleeding.

5

Endoscopy may be preferable to diagnose polyps; endoscopy or ultrasonography todiagnose inflammatory bowel disease; and nuclear medicine studies to diagnose Meckel’s
diverticulum.

39

out in Section 2, a good approach to justification is to audit the effectiveness ofthe process in practice.
Once an investigation has been justified, the path to follow will depend
upon the clinical indication, and on the alternatives, such as ultrasound, CT, MRI,
endoscopy, etc., that are realistically available in the time scale required. With
this caveat, fluoroscopy continues to play a significant role in medical imaging.
Micturating cystourethrography and gastrointestinal contrast studies, among
other examinations, are regularly performed.
5.1.2.

Optimization of protection and safety in conventional fluoroscopy

Once it has been decided to perform an examination, it has to be undertakenwith a protocol that includes optimization for the specific equipment and facilities
available, and for the requirements of the patient involved. Modern fluoroscopy
systems tend to be provided with powerful ergonomically convenient software
control systems. These allow exposures and full examination protocols to bepre-programmed, for both fluoroscopy and fluorography. In clinical practice, thiscan be a great strength but from a radiation protection perspective it may beproblematic.
This can be so in particular if the pre-set protocols are for adults or larger
children. Thus, it is essential to ‘child-size’ the protocols for the equipment inuse [10, 20]. Within the category ‘child-size’, it is further necessary todifferentiate protocols for children of differing ages and sizes. This cannot beassumed to have been done even in equipment supplied for paediatric use. Thus,
it is essential to adopt the team approach to protocol development identified inTable 17.
The staff operating the systems need to be comprehensively trained in thesystems’ characteristics. Otherwise, these systems will result in exposures thatvary over several orders of magnitude without the operator being aware of it.
With such units, the traditional classification of fluoroscopic exposure levels as‘high’ or ‘low’ becomes difficult to interpret or, on occasion, meaningless inpractice, even though the regulatory framework surrounding these classifications
continues to exist in some areas.
Participants in the team approach need to include a radiologist, medical
radiation technologist, medical physicist and clinical engineer; and the service
engineer and application specialist from the manufacturer. The team has to ensurecompliance with local regulations and, perhaps even more importantly, it also has
to ensure that those operating each system understand its features and theterminology used by the suppliers.
Training of the radiologist and medical radiation technologist in theoperational features of each fluoroscopy and fluorography exposure system

40

TABLE 17. TRAINING FOR DOSE MANAGEMENT
A team approach to dose management in fluoroscopy is essential. Participants in the teaminclude: a radiologist, medical physicist, medical radiation technologist, clinical engineer,company service engineer and company application specialist.
Training of the radiologist and medical radiation technologist in the specific operationalfeatures of each fluoroscopy system in use is essential.
Where non-radiologists (e.g. cardiologists or orthopaedic surgeons) are directly involved withthe use of these systems, certified training needs to be provided for them within the national
regulatory framework.
In larger departments, consideration needs to be given to training a trainer who will be fully
conversant with the equipment and with how to introduce new or rotated staff to it.

employed is essential. In larger departments, consideration needs to be given to
training a trainer who will be fully conversant with the equipment and with how
to introduce new or rotating staff to it [92]. In some areas, consideration is being
given to credential programmes that are machine specific. Such programmes
already exist in other areas such as medical laser safety and with the training ofairline pilots [93].
The examination technique is very important in optimization, and someguidelines are provided in Table 18. Table 19 provides useful additional
information on dose levels at the entrance of the image receptor in different
acquisition modes.
As with general radiology, positioning, collimation and selection of
exposure factors are essential in optimization in fluoroscopy [94]. Coning to asmall field of view can be achieved by the operator by using a light beam
diaphragm, rather than fluoroscopy, for guidance; radiation-free adjustment of the
primary and semi-transparent collimators may also be used if available. A low
attenuation carbon fibre table may be used where possible; these are available
from most fluoroscopic equipment manufacturers.
A removable anti-scatter grid needs to be available. This would normally
only be used for older children (over 8 years of age) unless a younger child isparticularly large. Such a grid may also need to be used in fluoroscopy forchildren where very high detail is required [62, 65]. Added copper filtration(e.g. 0.3 mm) can be used and can be left permanently in place if the equipment isused solely for children.
An overcouch tube may have significant advantages for general
fluoroscopy in a paediatric department, provided that the operator is fully trained.
This equipment configuration is less frightening for a child than that with anundercouch tube. It may slightly increase radiation dose but it makes access to thechild easier for the operator and for carers and comforters, and it reduces the timerequired for the study. In operation, the distance between the tube and the image

41

TABLE 18. OPTIMIZATION IN CONVENTIONAL AND INTERVENTIONALFLUOROSCOPIC TECHNIQUESGeneral applicability
Positioning, collimation, selection of exposure factors in optimization, etc. are essential influoroscopy.
The protocol needs to be ‘child-sized’, and the lowest dose protocol possible for patient size,
frame rate and length of run needs to be used.
Fields need to be tightly aligned to the area of interest using the light beam diaphragm rather
than fluoroscopy. The footswitch needs to be tapped to confirm position.
The image intensifier and/or receptor needs to be positioned over the area of interest before
fluoroscopy is commenced rather than positioning during fluoroscopy.
Field overlap in different runs needs to be minimized.
Eyes, thyroid, breast and gonads need to be excluded whenever possible.
Use of electronic magnification needs to be minimized; digital zoom needs to be used wheneverpossible.
A low attenuation carbon fibre table needs to be used where possible.
A removable grid needs to be available, but is normally only to be used with older and large
children (over 8 years of age).
Added copper filtration (e.g. 0.3 mm) needs to be used and can be left permanently in place if
the equipment is deployed solely for children.
Pulsed fluoroscopy needs to be available and used where possible. Many workers recommend
3.5–7.5 pulses/s as adequate for guidance and/or monitoring of most procedures.
Static fluoroscopic or fluorographic images or the ‘last image hold’ facility need to be used toreview the anatomy and/or findings.
An overcouch tube may be advantageous in paediatric radiology, provided that operators are
fully trained to protect themselves from irradiation of the upper body, head and neck.
Fluoroscopy timing alerts need to be acknowledged during the procedure.
A calibrated kerma area product meter needs to be available and used effectively.
The dose needs to be recorded and reviewed.
Special emphasis on interventional fluoroscopy
The number and timing of acquisitions, contrast parameters, patient positioning and suspensionof respiration need to be planned and communicated to the radiological and sedation team in
advance to minimize unneeded runs. The plan needs to be communicated to the team members.
Each run needs to be necessary for diagnosis or to assess progress and/or outcome.
Acquisition parameters need to be adjusted to achieve the lowest dose necessary to accomplish
the procedure: the lowest dose protocol possible needs to be used, account being taken ofpatient size, frame rate and length of run.
The patient table needs to be kept as far from the X ray source as possible and the image
intensifier and/or receptor needs to be as close to the patient as possible. The table needs to be
moved away from the X ray tube in both planes. The patient needs to be moved as close as
possible to the detector in both planes.
Fluoroscopy only needs to be used to evaluate a moving target or structure, and fluoroscopy
time needs to be limited.

42

TABLE 19. ENTRANCE EXPOSURE RANGE AT
THE IMAGE RECEPTOR IN TERMS OF AIR
KERMA FOR VARIOUS ACQUISITION MODES
Operational mode

Air kerma rangea(nGy/image)‘Low’ fluoroscopy

6.0–8.5‘Medium’ fluoroscopy

12–17‘High’ fluoroscopy

24–34

Digital angiography

450–900

Digital subtraction angiography

4500–9000

Cardiac digitala

90–130For a 23 cm image receptor, normal exposure rate, 30 pulses/s,
80 kVp and a standard total filtration of 2.5 mm Al.

intensifier needs to be maximized, with the table as low and as close as possible
to the image intensifier [37].
With larger children and adolescents, the well known risks of these systems
for the operators come into play owing to the increase in scattered radiation. Thisrequires awareness on the part of the operators. In addition, it needs to be borne inmind that such systems are often designed and intended for use in the remotecontrol mode, which generally allows the operator and attending staff to be in theprotected console area. Obviously, this will not always be possible with smallchildren, and the consequent risks to staff and to carers and comforters will
require careful management.
Pulsed fluoroscopy can be effective in reducing dose, and it needs to beavailable and used where possible. It is a standard feature of modern equipment.
Most fluoroscopy units have a range of 3–7.5 to 15–30 pulses/s. The lower range
is satisfactory for many procedures and can be increased if the child is very
mobile or uncooperative or if better detail is required.
Static fluoroscopic or fluorographic images may be reviewed from thedigital or pulsed system (e.g. using last image hold) rather than from ongoing
exposure. In addition, the duration of fluoroscopy and the number of images indigital runs need to be minimized with a view to dose reduction. Finally, it isworth noting that most doses to staff arise from radiation scattered from thepatient, so that measures to reduce the dose to patients usually have acorresponding benefit in reducing doses to staff.

43

Fluoroscopy systems generally emit audible periodic time alerts.
Acknowledging the cumulative timing device alerts may help in minimizing
doses in the procedure.
A KAP meter is helpful in achieving knowledge of the dose used and isrequired by law in many countries [5, 93]. It is of value both for the patient recordand as a training tool. A record of the information provided by the KAP needs tobe transferred to the RIS/PACS systems. Ideally, future generations of equipment
will be more flexible in this regard [50].
The KAP in fluoroscopic studies in children has to be kept as low asreasonably achievable, consistent with the diagnostic information required.
However, the doses involved can be expected to vary depending on the age, sex,
body mass, body thickness and cooperation of the child. The doses will also varywith the imaging objectives. Hiorns et al. have demonstrated that, for the eight
most commonly performed fluoroscopic examinations, dose values which are afactor of between 5 and 25 less than the current national DRLs can beachieved [37] (see Section 5.3). The authors attribute this to improvements inboth equipment performance and operator technique.
It is, therefore, recommended that paediatric fluoroscopy be conducted in
specialist units whenever possible. When not possible, for example innon-specialist radiology departments with responsibility for paediatric imaging,
the task may be assigned to a group of specially trained and experienced
radiologists and medical radiation technologists (and other suitably trained
professionals where appropriate, e.g. cardiologists).

5.2. DIAGNOSTIC AND THERAPEUTIC INTERVENTIONAL
PROCEDURES
Interventional and more sophisticated diagnostic fluoroscopic proceduresare generally conducted using purpose designed equipment that meets additional
requirements, particularly in respect of real time monitoring of skin dose and/or
dose rate [95]. The risk of high doses to patients and staff is much greater withthese procedures. With care, however, both can be controlled, so that both
operator and patient are not at unnecessary and/or undue risk. These procedures
often provide a therapeutic benefit to the patient, and this needs to be included in
the justification process.
Many of the measures that reduce doses to patients and staff in conventional
fluoroscopy (described in Section 5.1.2) and the requirements set out inTables 16–18 are also essential here. However, additional risk arises, such as thepossibility of deterministic injury to the patient; thus, some points need extraemphasis, and additional precautions are required.

44

5.2.1.

Justification in diagnostic and therapeutic interventional proceduresInterventional procedures in children are now more in demand, moresophisticated and take longer. Paediatric interventional procedures require
individual justification and planning. This has to include a balancing of the risk
against the therapeutic benefit. Such procedures, particularly for small infants,need to be undertaken by experienced paediatric interventional operators, bothfor clinical and for radiation protection reasons.
The procedure is to be performed only when absolutely necessary. As
already mentioned (see Table 16), it is important to ask the referring practitioner,
the patient and/or the family about previous procedures. Determination that theprocedure is necessary relies on the judgement of the radiological practitioner andon its complexity. Referral guidelines for therapeutic interventions (even for
adults) are not yet widely agreed upon [96–98].
With adults, there are wide variations in the numbers of therapeuticinterventional procedures performed from country to country; even within one
country, interregional variations in both numbers and complexity can besubstantial. This partly reflects the general levels of socioeconomic provision but
also reflects the level of staff training and the range of skills the individual
practitioner has cultivated to a high level.
The provisions of Table 16 need to be followed, as far as possible, except
for the recommendation about referral guidelines. The recommendations on audit
and information provided to the patient need to be considered. In particular, it is
now common to recommend that the patient be explicitly and fully informed in
the case of interventions.
An IAEA study with the purpose of investigating the level of radiation
protection of patients and staff during interventional procedures in 20 countries inAfrica, Asia and Europe also included an analysis of the workload of paediatricinterventional procedures [99]. Nearly 40% of the interventional rooms had anannual workload of more than 2000 patients in total. About 30% of participating
countries have shown a 100% increase in workload in 3 years.
Analysis of the workload in participating centres indicated that mostparticipating general hospitals perform paediatric procedures as well. The
percentage of children in the total annual workload varies enormously between
participating hospitals (0.2–35.4%). The number of paediatric patients comparedwith adults shows that in 2 countries the paediatric workload is in the range of
40–50% of adult procedures, 7 countries have 5–17%, and in the remaining
11 countries it is less than 5%.
The annual workload in dedicated paediatric hospitals in three countries
was also variable, ranging from 240 to almost 4000 procedures per year. Of theprocedures in paediatric hospitals, 2–36% are therapeutic procedures. However, it45

is remarkable that the workload of paediatric interventional procedures can reachthe levels of adult procedures even in developing countries. Special attention todose is, therefore, required. It is essential to thoroughly investigate the level ofradiation protection and the level of training in as many countries as possible, andin as many hospitals within each country as possible. This is necessary to evaluate
the potential for improving the protection of children, given that for paediatricpatients, risk of stochastic effects is the main issue [99].
5.2.2.

Optimization of protection and safety in diagnostic and/or
therapeutic interventional proceduresComplex interventional procedures can give rise to large doses to patientsand staff, and have been shown to cause high peak skin doses in adults and higheffective doses in children. The measures already specified in Table 18 will also
contribute to reducing doses to patients in interventional work. Some additional
considerations are listed in Table 19. The training and team issues alreadymentioned in Section 5.1 (see Table 17) are also essential here. It is wellrecognized that operator training improves performance with interventional
procedures conducted on adults [96].
Likewise, in paediatric interventions, it has been demonstrated, in a study
involving over 1000 procedures, that specific training improves the use of safetymeasures. This included use of hanging lead shields and lead eye glasses.
Training reduced imaging time and KAP significantly for relatively
uncomplicated procedures but was not as effective in bringing about change forcomplicated ones [92].
Complex procedures need to be pre-planned, and what is expected to be
involved needs to be communicated to the team. For example, the number andtiming of acquisitions, contrast parameters, patient positioning, suspension of
respiration and sedation needs to be planned in advance, to the extent possible, tominimize improper or unneeded runs. The acquisition parameters need to be
selected to achieve the lowest dose necessary to accomplish the procedure, withaccount taken of the dose protocol, patient size, frame rate, magnification andlength of run. During the procedure, the operator has to ‘step lightly’ on the
fluoroscopy pedal [10].
The table needs to be moved away from the X ray tube in both planes tomaximize the distance between the source and the patient. The distance will
generally be greater than 37.5 cm [10]. The image intensifier (or flat panel
detector) needs to be as close to the patient as possible, to minimize patient todetector distance, while allowing room for manipulation of needles, wires andcatheters. These considerations apply to all projections: vertical, lateral andoblique.

46

Image acquisition using fluorography or during digital subtraction
angiography accounts for the largest radiation doses during many interventional
procedures [100, 101]. Exposure factors for fluorographic image acquisitions andquasi-cine runs are much higher than those for fluoroscopy. The acquisition modeneeds to be carefully selected as dose rates involved can be up to a couple oforders of magnitude higher than for fluoroscopy [102, 103].
When C-arm RIS equipment is used, the proximity of the skin to the X raysource in lateral and oblique views might be closer than during the PA view, andmay result in an increase in skin dose. After the tube is placed in the lateralposition, the patient needs to be distanced from the source to the maximum extent
allowed by the equipment. In attending to this, the dose readout systems that area feature of interventional equipment need to be consistently employed by theoperator as part of their active monitoring of the procedure [50, 95]. The
cumulative readouts from these systems need to communicate readily with the
PACS and RIS systems.
Paediatric interventional procedures have unique features related to patientsize. Patient sizes vary in practice, from as small as 450 g to in excess of 100 kg.
To gain access to the small child, it is often necessary for the interventionist tocome close to or, on occasion, enter the beam. The operator’s hands may bedirectly in or immediately adjacent to the beam during a procedure such as acentral line placement or abscess drainage. They might also enter the beamurgently when an unexpected event or a complication occurs.
It is well known that with heavier children the indicators for patient dose
increase [104]. However, it is further recognized that children are not small
adults [105]. As mentioned above, imaging equipment needs to be specificallydesigned for use with children and the operators need to be trained accordingly.
The generator needs to provide a large dynamic range of current (mA) and tube
output index for defined kV (the product of tube current and time (mAs)) tominimize the range of kVp and the exposure time needed to compensate fordifferences in thickness. It is also desirable for there to be three focal spots, alateral imaging plane, spatial and spectral beam profiling, and a well functioning
system of entrance exposure regulation. Strauss recommends the entrance
exposure values at the image receptor listed in Table 19 [105]. He also provides
suggestions with regard to how these values can be adapted to other operating
conditions.
Another unique feature in paediatric intervention is the large size of image
intensifiers or digital image receptors relative to an infant’s size. With infants andsmall children, the image intensifier will completely cover the patient. In suchsituations, the accuracy of collimation is more important than for adults, where
the field of view is often allowed to fill the image receptor field. This is
unacceptable in paediatric cases. Thus, ensuring that the collimation is precisely

47

aligned becomes a key design, performance and quality assurance issue. There isalso an increased need to use magnification in children. This can further increase
dose when analogue magnification is unnecessarily used [100].
After the procedure, the dose records may be noted and reviewed. A doserecord may be included in the medical record [50, 95]. The ‘step lightly’
campaign recommends audit of radiation doses for all operators [10]. Specificfeedback and additional training need to be provided where necessary [20, 21].
Implementing the above measures needs to be balanced against safe,
accurate and effective completion of the procedure. Not all of the steps mentioned
may be possible in each case, depending on patient size, the technical challenge
and the critical nature of the procedure. The goal is to minimize the dose to thepatient while providing important and necessary medical care.

5.3. DOSES TO PAEDIATRIC PATIENTS AND REFERENCE LEVELSFOR FLUOROSCOPY AND INTERVENTIONAL PROCEDURES
Only limited data are available for reference dose levels for both
fluoroscopic and interventional paediatric procedures. The available data are notcompletely satisfactory as they are dependent on the generation of the technology
on which they were measured.
Three sets of data available for fluoroscopy from the United Kingdom areillustrated in Table 20. The third column from the left provides the current
national reference doses for paediatric fluoroscopy (2005 review) [89]. The
column to its right provides the set of national reference doses that prevailed in
the 2000 United Kingdom review [106]. Clearly, the reference doses werereduced in 2005 in all cases except one, the barium swallow at 10 years of age.
This demonstrates the value of an ongoing national programme of monitoring andof hospital involvement and/or collaboration in this area.
The reduction observed is consistent with the pattern reported by the HealthProtection Agency for other examinations in adults. It may also be noted that thereference doses are set at the third quartile level, which means that 75% of those
involved achieve lower values. Additional data to this effect are provided in the
United Kingdom reports [89, 106].
The right hand column of Table 20 lists local DRLs established at Great
Ormond Street Hospital, London [37]. Hiorns et al. have also demonstrated that,with the eight most commonly performed examinations (2215 cases), the KAPs
(75th percentile) for upper gastrointestinal studies and micturating cystograms
are substantially lower (by a factor of between 5 and 25) than the current nationaldoses. Some of the median values are 50 times lower. Their small KAP values inall examinations demonstrate the substantial reduction in dose and, consequently,

48

TABLE 20. COMPARISON OF THE UNITED KINGDOM’S REFERENCEDOSES (2005 AND 2000) FOR PAEDIATRICS AND DIAGNOSTICREFERENCE LEVELS AT GREAT ORMOND STREET HOSPITAL [37, 89, 106]

Examination

Micturating
cystourethrogram

Barium meal

Barium swallow

Age (a)2005 nationalreference doses(cGy ⋅ cm2)

2000 review
kerma area
product
per exam(cGy ⋅ cm2)

Great OrmondStreet Hospitaldiagnostic
reference level(cGy ⋅ cm2)

0

30

40

5

1

70

100

5

5

80

100

10

10

150

210

42

15

250

470

42

0

40

70

8

1

110

200

8

5

130

200

12

10

240

450

32

15

640

720

32

0

40

80

8

1

120

150

8

5

130

150

12

10

290

270

32

15

350

460

32

in risk that can be achieved when both equipment performance and operator
technique are optimized.
While different institutions will have differing practices, it is important thatpractitioners be aware of the range of KAPs achievable and of the fact thatnational or international DRLs do not necessarily represent best practice, andmay in fact be falsely reassuring. The Great Ormond Street Hospital values are acompelling example of what can be achieved with a dedicated approach [34]. The
figures in the table also illustrate the spread in values that arises, and are areminder of the need for much more work in the area. Other studies confirm thatlarge dose savings can be achieved with relatively straightforward technicalstrategies [107]. The results of a limited European survey are available and havebeen published [71]. Some details are provided in Appendix III.

49

With regard to interventional radiology and cardiology, there has been asignificant growth in the literature available worldwide in the past decade.
Studies are now available for adults in respect of reference values, the mean dose
per procedure and local DRLs [31]. While these techniques are now commonlyused in paediatric radiology, few studies are available detailing the doses orfrequencies involved.
However, Onnash et al. report mean effective doses and KAP normalized tobody weight in interventional cardiac procedures as illustrated inTable 21 [1, 108]. This may prove to be a useful approach from the point ofview of paediatric radiology. It may, with some care, be used to draw on adultstudies pending a larger range of paediatric data becoming available [108].
Deterministic injuries following interventional procedures that have beenreported in adults, and their time course and/or dose relationship, are presented inTable 22 [109]. They include serious injury to skin and underlying tissues, althoughthese are less likely in children than in adults. Many of these injuries may be missed
as they become manifest after the patient has left hospital and/or the team caring forthe patient may not be aware of the risk of radiation injury [100].
To help avoid these injuries, modern interventional equipment generally
provides a dose estimate at the interventional reference point. The IEC defines
the interventional reference point as 15 cm from the isocentre towards the X ray
tube [50, 95]. The interventional reference point is related to the dose to the skin.
Where it is suspected that a patient has received a high skin dose (2 Gy or more),a follow-up visit 30 days after the procedure has to be planned. The parents
and/or the patient have to be informed that if symptoms of skin injury (i.e. skin
TABLE 21. EFFECTIVE DOSE AND MEAN KERMA AREA PRODUCTPER KILOGRAM FOR A SELECTION OF PAEDIATRIC CARDIAC
INTERVENTIONS (based on Ref. [108])
NumberMean kerma
area product(Gy ⋅ cm2 ⋅ kg–1)

Effective dose(mSv)

Atrial septal defect occlusion

259

0.42

3.9

Patent ductus arteriosus occlusion

165

0.35

3.2

Balloon dilatation

122

0.48

4.4

Coil embolization

33

0.50

4.6

Ventricular septal defect occlusion

32

1.3

12

Atrial septostomy

25

0.39

3.6

Patent foramen ovale occlusion

21

0.23

2.2

Procedure

50

TABLE 22. DOSE, TIME AND DETERMINISTIC INJURIES [109]Peak skindose band

Range
(Gy)

Prompt:˂14 d

Early:
14–40 dMid-term:
40–400 dLate:
˃400 d

A1

˂2

A2

2–5

TransienterythemaTransienthair thinning

Hair recovery

None expected

B

5–10

Transienterythema

Erythema,
epilation

Recovery;at higher doses,
prolonged
erythema,
permanent
epilation

Recovery;skin changes
at higher
doses

C

10–15

Transienterythema

Erythema,
epilation,
possible dryor moistdesquamation

Prolonged
erythema,
permanent
total epilation

Telangiectasia,
induration;skin likely
to be weakD

˃15

Transienterythemawith possible
pain; oedema
and acuteulceration atvery high dose

Erythema,
epilation, moist
desquamation

Dermal atrophy,
secondaryulceration,dermal necrosis

Dermal atrophy,
induration,late skinbreakdown;
persistent wound;
surgicalintervention likely

No effects expected

irritation or reddening) occur, these have to be reported to the department inwhich the procedure was performed.

5.4. DOSES TO STAFF IN FLUOROSCOPY,
INCLUDING INTERVENTIONAL FLUOROSCOPY
The team approach already mentioned needs to be adopted for managementof staff doses. All team members need to be aware of the radiation exposure issues
with fluoroscopy and interventional procedures, and the means of controlling them.
In practice, those operationally involved need to be recognized radiological medical
practitioners and medical radiation technologists — i.e. they have the requisite
specialist education and training, including in radiation protection. This may mean,
as is required in many countries, that they need to undergo special training in thetechniques involved and in radiation protection [47, 100].

51

The requirements for good practice have much in common with the practicefor adults but are adapted for paediatric radiology. The main features arepresented here for ease of reference. Exposure of staff can arise from the direct
beam or from scatter from the patient. For a well designed set up with good
protocols, there will be little risk of exposure to the direct beam, with the
exception of those circumstances where the operator’s hands may, for exceptional
reasons, be in the beam for short periods (see below). This apart, most exposureof staff, in practice, arises from scattered radiation.
It is widely recognized that for a given set-up, doses to both patients andstaff are dependent on the total amount of X ray energy emitted from the tube.
The connection between doses to staff and doses to patients also arises from thefact that most exposure of staff is due to scattering of radiation from the patient.
Vano et al. have demonstrated a linear relationship between KAP to the patientand staff doses in cardiac simulations [110, 111].
Thus, minimizing exposure of staff will be facilitated by optimization forthe patient. Many researchers have demonstrated that the exposure regime and/or
protocol employed is very important in determining doses to staff. For example,
in digital fluoroscopy, cine, digital ‘cine-like’ or digital subtraction angiography
runs, the dose to staff due to scattering of radiation from the patient can be several
orders of magnitude higher than during fluoroscopy [110–113].
Doses to staff are also dependent on the size of the patient, which influences
the amount of scatter. The amount of scatter is also influenced by the complexityof the procedure and by the adequacy of the training and experience of theoperating staff [92, 95]. Simulation studies by Vano et al. have demonstrated thatthe dose to staff due to scattering of radiation from larger children is likely to behigher by a factor of up to 20–30 than that due to scattering from infants [110].
To reduce exposure to scattered radiation, staff need to position themselves
strategically with respect to the configuration of the image receptor and the X raysource assembly (Table 23). The operator generally needs to be on the image
receptor side and, where possible, to step back during injections. The dominantdirection for scatter tends to be from the patient backwards towards the X ray
tube. This is well illustrated in Balter’s diagrams [111], which are reproduced inAppendix IV.
Operators need to become familiar with the profile of scattered radiation in
the room when the tube is oriented in the main directions used in practice. Where
equipment has been designed and sold for interventional use, the suppliers, incompliance with international technical standards [114], have to provide isodose
curves such as those shown in Appendix IV [47, 92]. The room floor could becolour coded to help staff position themselves in such a way as to minimize
exposure. While Balter’s data are based on adults, they provide some guidance52

for paediatric interventionists, pending the availability of more complete
paediatric data [110, 111].
During interventional procedures, the staff member most at risk is theoperator. Others need be in the room only if their presence is required. All need tohave adequate personal protection, such as good, well designed lead aprons,
thyroid collars and lead glasses, as required. Where paediatric interventionists
performing these procedures spend much of their working life wearing leadaprons, the risk of back or joint injury needs to be considered.
Two-piece aprons are available which redistribute the weight so that it is not
all carried on the shoulders. Wrap-around aprons are also now available in which
the shielding is biased towards the front, where the risk of exposure is higher for
most of those involved. Leaded thyroid collars and/or lead glasses (prescription
and non-prescription are available) with side shielding need to be worn in view ofincreasing concerns about occupational exposure [115].
Radioprotective gloves can attenuate scatter by about 50% but can becounterproductive if inadvertently placed in the beam, as they may interfere with
the AEC and increase exposure. They also reduce dexterity and speed, hinder thework and can give a false sense of security. If, exceptionally, hands need to beplaced in the beam, they ought, if possible, not to be placed between the X ray
tube and the patient. Foot and leg doses to the operator can be significant and arereceiving increasing attention as procedures become more complex and longer.
Lead skirts for the table or drapes of newer compound material can reduce thescatter of radiation to the legs and ankles by as much as 10- to 20-fold [111, 116].
It is now possible to obtain single use drapes for scatter reduction.
In a study of adults, use of a power injector instead of hand injecting contrast
material has been shown to be a highly effective way of reducing operator dose
during angiography [117]. While the reductions may not be quite as dramatic in
paediatric radiology, injectors need to be used where possible. In addition, theoperator needs to step away from the image intensifier and/or behind a mobile lead
screen during contrast injections. When manual injection is necessary, the distancefrom the patient needs to be maximized by using a long catheter.
Occupational dose measurements have to include readings from at least one
dosimeter under the lead apron to assess whole body dose. Additional dosimeters
over the apron to evaluate thyroid, hand and arm, and eye doses are advisable insome situations. For example, the ICRP recommends two dosimeter badges forinterventional work, one under the apron and one on the shoulder over the apron.
The second dosimeter is sometimes taken as being indicative of doses to areas
such as the eyes, head, neck and even thyroid, and both are used in estimating
effective dose [118]. Slight angulation of the beam away from the hands, strict
collimation and careful attention to finger positioning will help to reduce
exposure of the operator.

53

TABLE 23. REDUCING DOSES TO STAFF IN INTERVENTIONALFLUOROSCOPY
Only those necessary for conduct of the procedure are to be in the room.
Personnel needs to be moved away from the table, preferably behind protective shields duringacquisitions.
The operator needs to stand to the side of the image intensifier.
The operator (and other team members) may step back during injections.
The operator needs to use a power injector and to step back from the image intensifier and/or
behind a mobile lead screen during contrast injections.
If manual injection is necessary, the distance needs to be maximized using a long catheter.
Doses in the room and from undercouch tubes can be greatly reduced by well configured andproperly used tableside drapes.
Movable overhead shields need to be used for face and neck protection. These need to bepositioned prior to the procedure.
Well designed suspended shielding and/or viewing systems are helpful to operators who learn
to become skilful in their use.
Suitable, well fitted radioprotective aprons of appropriate weight need to be worn.
Aprons need to be well fitted, with arm wings to protect the axillary tail for females.
A thyroid collar and/or lead glasses with side shielding need to be worn.
The operator and personnel need to keep their hands out of the beam.
When, exceptionally, hands need to be placed in the beam, they ought, if possible, not to beplaced between the X ray tube and the patient.
Radioprotective gloves may be worn where appropriate, but they can be counterproductive,
reduce flexibility and dexterity, and interfere with the automatic exposure control.
Slight angulation of the beam off the hands, strict collimation and careful attention to finger
positioning will help to reduce exposure of the operator.
Occupational dose measurements need to include at least one dosimeter badge under the leadapron to assess whole body dose.
Additional dosimeter badges over the apron to evaluate thyroid, hand and arm, and eye doses
are advisable in some situations.

With large KAPs and work in which the operator, for effectiveness, needs toremain close to the patient, the risk of high doses to the head and neck of theoperator from scattered radiation will arise. In this context, any gain from thesmall size of the patient may be offset by the closeness of the operator and/or thecomplexity of and the dexterity necessary for the manipulation involved in theprocedure. This can often be the case in paediatric interventional cardiology.

54

In studies [110, 115], Vano et al. have drawn attention to the risk of damage
to the eyes of the operator and estimate that the eye dose will be about
7 µSv · Gy–1 · cm–2 of KAP to the patient. Table 23 provides a summary of manyof the key points discussed above. For maximum impact, it is essential that theadvice of the medical physicist and/or RPO be obtained to allow local protocols
and the physical environment to be considered in the optimization of protection
and safety for staff.

55

6. COMPUTED TOMOGRAPHY
In developed countries, over 10% of diagnostic radiological procedures are
CT examinations. In the USA, the total number of CT examinations per year for
all age groups is about 60 million, of which 7 million are paediatric [1, 10].
Paediatric CT is a valuable imaging tool, the use of which has been increasing at
a rate of about 10% per year recently. An eightfold increase has occurred over the
past 20–30 years [7, 10]. The rate of increase in examination numbers may beeven greater in special cases.
Given the evidence of CT (over)utilization in recent years, in particular in
the USA, there are organized efforts to increase radiation awareness and promote
safety in paediatric imaging [10, 119]. Availability of alternative imaging
modalities that do not require the use of ionizing radiation and careful review ofbody CT requests in US paediatric hospitals contributed to a significant decreaseof CT utilization in 2006 and 2007 [119]. Some authors believe that many ofthese examinations may not be necessary or justified (see Section 6.1). The dosefor each individual examination is relatively high. CT is not the most frequentexamination but it contributes the largest component of the collective dose frommedicine, 50–67% in some US tertiary referral centres [120–122].
While the situation in paediatric CT is not fully documented, it has led toincreasing concern about the exposure of children, particularly as adult scansettings were used in paediatric CT for many years. Consequently, muchcomment and advisory material addressing the area has been developed. This
includes that from the US Food and Drug Administration, the US National
Cancer Institute (NCI), the National Council for Radiation Protection, and theincreasingly visible Image Gently Campaign, in addition to that fromprofessional bodies [7, 10, 20, 123].

6.1. JUSTIFICATION IN COMPUTED TOMOGRAPHY
The references in the previous section generally include advice thatpaediatric CT has to be justified. This is not surprising as some authors haveestimated that between a third and half of the examinations occurring may not benecessary, and many are conducted using inappropriate technical factors[32, 124]. At the extreme, Oikarinen et al. [32] report that 77% of lumbar spine
examinations in their study of a population under 30 years of age were notjustified.
This issue has also been given added impetus by a growing active press andmedia interest in the area, since about 2007. Government and professional bodies

56

in the USA now have a consistent response which includes justification [7, 10,
15, 17, 123]. Some specific approaches would have an immediate impact inreducing paediatric doses. Examples are summarized from these and othersources in Table 24. While many of these are generic, they are included here as
they are necessary when planning an operational response and for ease ofreference and/or completeness.
It is required that each CT examination be rigorously justified. In thisregard, tools such as the evidence based referral guidelines mentioned earlier are
helpful, and those published by the EC are reproduced in Appendix II with the
caveats already noted (see Sections 2, 4 and 5) [27–31]. Some workers havedeveloped or added local guidelines or referral protocols. These are helpful where
they are well understood and well incorporated into a local practice [9]. For
example, Broder discusses the value of rules and guidelines in limiting CT
overutilization in the emergency room setting [125]. The following paragraphs
TABLE 24. IMMEDIATE STEPS TO REDUCE PAEDIATRIC COMPUTEDTOMOGRAPHY DOSES [7, 9, 123]
Immediate steps to reduce paediatric CT doses
CT examination is required to be rigorously justified and inappropriate referrals eliminated.
Only necessary CT examinations are to be performed.
The number of multiple scans with contrast material needs to be reduced.
The referring practitioner, patient and/or family needs to be asked about previous procedures.
Referral guidelines need to be used where appropriate.
Alternative approaches, such as ultrasound or MRI, need to be used where appropriate.
Information needs to be provided to the patient in accordance with the BSS or national
standards.
Justification needs to be included in clinical audit.
Some specific measures to assist with these objectives
Age specific pathology and its prognosis need to be respected.
Individual paediatric questions need to be respected.
The potential contribution of the scan to patient management and outcome needs to be considered.
The patient’s record and previous radiology examinations need to be considered.
Cost and radiation exposure need to be respected.
CT needs to be replaced by an examination with no or with lower radiation exposure(e.g. ultrasound or MRI).
The follow-up examination needs to be delayed unless a decision based on the scan is neededat the time.

57

will be helpful in establishing local guidelines and/or in practically implementing
those from the literature.
Special attention is needed for age specific pathology, its prognosis,
individual paediatric questions, the costs and the radiation exposure involved in
an examination. Previous examinations are required to be considered [2], andtheir consideration is implied by the proposed IAEA Smart Card project and theImage Gently Campaign [10, 20]. This may render the procedure underconsideration unnecessary or allow it to be replaced by a less dose intensive one.
Likewise, the potential contribution of the scan to the management and outcomeof the patient’s condition needs to be considered. Follow-up examinations need to
be delayed unless therapeutic decisions based on them are needed immediately.
CT examinations need to be replaced, where appropriate, by others without
radiation or with lower exposure (e.g. ultrasound, MRI or conventional
radiography). In children, ultrasonography has to be the first line imaging studyof the abdomen since their slim body habitus allows access even to the deeper
abdominal structures. In experienced hands, ultrasonography can provide
substantial clinical information and may obviate the need for CT.
Ultrasonography has to be the examination of choice in children suspectedof acute appendicitis. CT need not be performed without a preceding clinicalexamination by an experienced surgeon. When ultrasonography and radiography
are unlikely to provide the answer, the choice of examination is often between CT
and MRI. The severity of the suspected disease, the study duration, radiation
exposure, side effects of anaesthesia and contrast agents, and specific information
required all need to be evaluated.
Problems requiring detailed information on soft tissues, the nervous systemor bone marrow are often best evaluated, in the first instance, with MRI. A large
body volume, time and anaesthetic restrictions under emergency conditions, suchas multiple trauma or the need for information about cortical bone, favour CT.
Malignant disease with a poor prognosis renders the potential detriment fromradiation exposure less important. Where there is a probability of curative
treatment, the added risk of many follow-up studies during and after treatment
has to be carefully assessed.
In all of these circumstances, it is important to reduce the number ofmultiple scans with contrast material. Often, CT scans are done before, during
and after intravenous contrast injections. Radiation exposure may be reduced byeliminating pre-contrast images. Repeated scanning of identical areas needs to beminimized and non-enhanced scans need to be avoided unless specificallyjustified. Where practical, the protocols may allow all, or as much as possible, of
the information required to be obtained during one scan.
A lower dose needs to be used for non-enhanced or repeat scans unless highquality is needed. Follow-up CT scans are not to be performed too prematurely

58

when, according to the known biology of the disease, one cannot yet expect a
response to treatment. Of the children that have undergone CT scans,approximately one third have had at least three scans [122]. Justification for
repeat scans needs to be as rigorous as for the first examination, and alternative
investigations may suffice.
There is also evidence suggesting how dependent usage is on thephysician’s environment. This is often felt to be driven by concerns about
litigation, heavy workload and pressure to make a rapid diagnosis. As mentioned
in earlier sections, clinical audit of justification can be an effective tool inproviding an incentive to reduce overutilization. The case for development anduse of guidelines and for clinical audit of justification has recently beenreviewed [17, 21].
As mentioned earlier, a programme of informing parents about the radiation
risks associated with relatively high dose procedures and the benefits of theprocedure is advisable. With the higher doses involved in many CT examinations,providing adequate information to the patient, parents and carers and comforters
takes on much greater importance. In addition, the question of an appropriate
level of information is not trivial. It is worth noting that there have been studies inwhich parents are given information regarding the risks and benefits of CT. This
did not result in reduced acceptance but it did result in more informed questions
being put to the care providers [10, 23, 24]. In the long run, while time
consuming, this is beneficial.

6.2. OPTIMIZATION IN COMPUTED TOMOGRAPHY
Many aspects of the acquisition of a study affect radiation dose and image
quality. These are required to be optimized. Some of the measures necessary toachieve this are relatively simple, as indicated in the recommendations summarizedfrom various sources in Table 25 [7, 9, 10].
Optimization is facilitated if the patient is well prepared, so that theexamination can proceed smoothly. Renal function needs to be checked andconfirmed, and hydration verified where relevant. Intravenous lines need to beplaced well in advance. Whatever steps are desirable to reduce anxiety and to
restrict movement need to be taken, including avoiding pain and, where valuable,
the use of medication, sedation, anaesthetics, and immobilization and positioning
aids, etc. Appropriate information needs to be provided to both the patient andaccompanying persons.
These steps reduce or eliminate movement of the patient and the associateddegradation of image quality. Image noise, contrast and artefacts have an
important influence on study quality. Factors such as scan time and pitch, which

59

TABLE 25.
GENERIC AND SPECIFIC REQUIREMENTS
OPTIMIZATION IN COMPUTED TOMOGRAPHY

FOR

Generic requirements
The patient and accompanying person(s) need to be informed and prepared.
It is necessary to be familiar with CT dose descriptors.
It needs to be realized that noise reduction means high doses; noise is acceptable if the scan isdiagnostic.
It needs to be ensured that operating conditions balance image quality and radiation exposure.
Scan parameters within the axial plane need to be considered in optimization.
A set of tube current settings for paediatric examinations needs to be considered in optimization.
Scan parameters for volume coverage need to be optimized.
A minimal length needs to be scanned, and repeated scanning of identical areas needs to beminimized.
Specific measures that assist these objectives
mAs/baseline mA needs to be reduced according to body weight and/or diameter or composition.
x–y-plane dose modulation needs to be used.
Tube filtration needs to be increased (if available).
A maximal slice thickness appropriate for specific diagnosis needs to be used.
The X ray tube voltage (kVp) needs to be decreased for thin patients.
Normally, the shortest rotation time available needs to be used.
A representative volume sample needs to be used when the entire volume is not needed.
A spiral scan with a pitch greater than 1 (e.g. 1.5) needs to be used, provided this does not
automatically increase the mA.
Thicker collimation with overlapping reconstruction needs to be used when thin slices are notneeded.
z axis dose modulation needs to be used.
It is necessary to be restrictive in defining uppermost and lowermost limits.
A localizing projection scan extending just minimally beyond scan limits needs to be used.
Additional thick noise-reduced slices need to be reconstructed without an increase in exposure.
Major overlap needs to be avoided when scanning adjacent areas with different protocols.
Non-enhanced scans need to be avoided unless specifically justified.
The protocol needs to be optimized to obtain all of the information requested during one scan.
The number of scans in multiphase scanning needs to be minimized.
In the case of multiphase scanning, a shorter scan length needs to be used for additional scans.
A lower dose needs to be used for non-enhanced or repeat scans unless high quality is needed.
A minimal number of additional sequential functional scans needs to be used.
Length of scans and fluoroscopy time need to be minimized in interventional applications.
Test bolus and/or bolus triggering needs to be replaced by standard scan delay unless timing isvery critical.
Additional protection devices need to be used where indicated (lens, thyroid, breast, gonads).

60

can be chosen, may affect the presence or absence of artefacts from motion. Withfaster table speed and gantry rotation, breathing artefacts in children may be
reduced.
In addition to the absolute quality of the image, it is necessary to beattentive to both the requirements of the diagnostic problem being posed and thenatural contrast levels available in the area being imaged. For example, the image
quality and dose necessary to visualize large bony structures may be less thanthose required to demonstrate fine vascular structure. Alternatively, more image
noise may be acceptable in skeletal or lung parenchymal examinations than inbrain or abdominal examinations, owing to the higher contrast differences in theformer. Thus, a chest examination with higher noise may have the same
diagnostic quality as a lower noise abdominal study.
Abdominal organs, such as the liver, kidney and pancreas, may show only
minimal density differences between normal tissues and pathological lesions, andwill consequently require higher doses to provide the signal to noise ratio
required for acceptable differentiation. Thus, acceptable scan quality will be
influenced by the clinical indication for the study. Smaller, low-contrast lesions
require higher contrast resolution. For example, more image noise may betolerated in a follow-up study to assess a fracture of the liver than in a study toassess the presence of small metastases.
The perception of study quality is also related to the display of the data.
Three dimensional reconstruction to determine bony outlines for surgicalplanning may be achieved at relatively low doses [9]. As with all digital studies,
the quality and adjustment of the display can have a significant impact on thequality of the final image displayed. A study viewed on the CT console may lookinferior when viewed on a monitor which is not set up for viewing examinations.
The ambient environment for image review will also be reflected in the perceived
study quality [102].
In reducing dose while maintaining diagnostic image quality, the presenceof noise needs to be accepted as long as diagnostic quality is not lost. Some
suppliers now provide advice on noise levels and suggest values which can besuitable for initial examinations, and different values which may be appropriate
for follow-up or repeat procedures. Extra technical information on how toapproach these possibilities is provided in Appendix V.
From a different perspective, breast tissue has to be protected in children,
without interfering with image quality. Bismuth breast shields are now available
for all paediatric age groups, from neonate to young adult. When used in an
appropriate setting, the bismuth shielding technique is still a valid and valuable
tool for reducing radiation risk in children [126]. Bismuth breast shields need to
be routinely used for examinations involving breast tissue. When z axis
modulation is used, it is desirable for them to be positioned after the localizer has

61been performed [127]. However, caution is raised based on recent results which
need to be kept in view to rationalize use of shielding [128].
The recommendations in Tables 24 and 25 are summarized from a numberof sources [7, 10, 123]. While many are technically simple and could well beapplied to radiology in general, they are repeated here because their importance inCT has sometimes been missed, and because they are important for thoseplanning a practical approach to dose reduction. Giving effect to them as a matterof institutional policy requires a broad commitment and team approach on behalfof the many professionals and individuals involved.
The Image Gently Campaign emphasizes and draws attention to this; its
recommendations for successful widespread application are summarized inTable 26 [10]. In the long term, additional initiatives are required and some ofthese are summarized in Table 27. Table 27 was developed from an NCI original
but has a number of additional recommendations [7].

6.3. COMPUTED TOMOGRAPHY AND DIAGNOSTICREFERENCE LEVELS
The area of CT dose measurement is unsatisfactory, in that it lacks
transparency for many end users. Among the reasons for this are the manydifferent metrics used for CT dose. At least three are commonly employed by the
medical physics community. These are CT dose index over the entire volume
scanned (CTDIvol), dose length product (DLP given in mGy ⋅ cm) and absorbed
TABLE 26. ADVICE FOR RADIOLOGISTS, MEDICAL PHYSICISTS ANDTECHNOLOGISTS FROM THE IMAGE GENTLY CAMPAIGN [10]Awareness of the need to decrease CT radiation dose to children needs to be improved.
It is necessary to be committed to making a change in daily practice through teamwork
between radiologists, medical radiation technologists, referring doctors and parents.
Medical physicists, radiologists and medical radiation technologists need to review CT protocolsand ‘down-size’ them for children.
Single phase scans are often adequate. Pre- and post-contrast or delayed scans rarely add
additional information in children but can double or triple the dose.
Only the indicated area needs to be scanned. If a patient has a possible dermoid on ultrasound,
there is rarely a need to scan the entire abdomen and pelvis.
It is necessary to be involved with the patients and to be their advocate. It is necessary to ask thequestions required to ensure that the scan is ‘child-sized’, and only the area required needs to bescanned.

62

TABLE 27. LONG TERM STRATEGIES TO MINIMIZE PAEDIATRICCOMPUTED TOMOGRAPHY RADIATION (based on National Cancer Instituterecommendations [7])Further development of referral and/or appropriateness criteria needs to be encouraged.
Further development and adoption of paediatric CT protocols need to be encouraged.
Clinical audit for justification needs to be encouraged.
The use of selective strategies for paediatric imaging, such as for the pre-surgical evaluation of
appendicitis, needs to be encouraged.
Industry and technical standards organizations need to be encouraged to produce innovative
standardized designs that address the issues of dose management for children.
Further research needs to be conducted to determine the relationship between CT quality anddose, to customize CT scanning for individual children, and to clarify the relationship between
CT radiation and cancer risk.
Journal publications and conferences need to be used to educate within and outside radiology
specialties to manage exposure settings for optimization purposes and to assess the individual
need for CT.
Information needs to be disseminated through associations, organizations or societies involved
in health care of children.
Readily available information sources on the Image Gently Campaign, IAEA Radiation
Protection of Patients and other relevant web sites need to be provided [10, 20].

dose (mGy). Other metrics are also often used. In addition, effective dose (given
in millisieverts) is frequently quoted, as it conveniently relates to risk, but there
are some reservations about this in the measurement community.
Discussion of these quantities and measurement systems is beyond thescope of this volume but they are reviewed at length and summarized in manysources [129–133].
Some typical paediatric CT effective doses in millisieverts and organ dosesin milligrays from the US NCI are reproduced in Table 28. The latter refers to theabsorbed doses in particular organs (mGy) and the former to effective dose,
which is a marker for whole body risk. Reference doses and typical doses fromvarious sources are available in a series of publications [7, 10, 134–139].
The NCI makes the following observations:“Effective doses from a single paediatric CT scan can range from about <1
to 30 mSv. Among children who have undergone CT scans, approximately
one-third have had at least three scans. Multiple scans present a particularconcern. In addition, more than one scan ‘phase’ may be done during asingle examination, further increasing the radiation dose. A single scan

63

TABLE 28. TYPICAL COMPUTED TOMOGRAPHY DOSES [7]Examination type
Head unadjusted (200 mAs)

Relevant organ

Range of absorbed
organ dose (mGy)

Range of effective
dose (mSv)

Brain

23–49

1.8–3.8

Head adjusted (100 mAs)

Brain

11–25

0.9–1.9

Abdomen unadjusted (200 mAs)

Stomach

21–43

11–24

Abdomen adjusted (50 mAs)

Stomach

5–11

6–12

Chest X ray PA

Lung

0.04–0.08

0.01–0.03

Chest X ray lateralLung

0.04–0.10

0.03–0.06

Note: ‘Unadjusted’ refers to using the same settings as for adults; ‘adjusted’ refers to settings
adjusted for body weight; PA: postero-anterior.

during paediatric CT may be sufficient in the vast majority of cases. The
highest lifetime risks estimated in the literature are less than 1 in 1000, andmost estimates are substantially lower than that. The public health issue isthe increasingly large paediatric population being exposed to these smallrisks. The benefits of properly performed CT examinations must always
outweigh the risks for an individual child” [7].
In practice, in potentially life threatening situations, multislice CT can be an
excellent tool. Good protocols are needed to ensure that the study is both justified
and optimized [139].
Table 29 provides information on CT doses in terms of the equivalent
period of natural background. There are also representations in terms ofequivalent number of chest X rays for each examination [20]. It can be seen that
this has considerable value in communicating with both patients and physicians.
Some radiologists have questioned the use of these scales on the grounds thatpatients or guardians may find it frightening to have a scan that is equivalent toseveral hundred chest X rays or many years of natural background radiation.
However, in the interests of patients, it is essential that a readily comprehensible
measure of dose and risk be available, as well as a sense of the real benefit to be
derived from the scan.
In Table 30, examples of United Kingdom national reference doses for
paediatric patients from various age groups and for different examinations areprovided [138], which are a valuable benchmark for practitioners. The weighted
CT dose index (CTDIw) values are provided for the purpose of comparison withhistorical values as this index has largely been replaced by CTDIvol as a reference
dose quantity. The reader is referred to the original publication for the full detailof the conditions that prevailed for the various measurements reported [138].

64

TABLE 29. TYPICAL DOSES FROM VARIOUS EXAMINATIONS,EXPRESSED AS EFFECTIVE DOSE AND IN EQUIVALENT PERIOD OF
NATURAL BACKGROUND WITH ASSOCIATED INCREASED CANCERRISK [20]Effective dose(mSv)

Increased riskof cancer

Equivalent period ofnatural backgroundNot defined
and/orapplicableNot known

Not equivalent

Low dose (chest X ray, extremities)<0.1

1 in 1 million

Few days

Intermediate dose (intravenous
pyelogram, lumbar spine, abdomen,head and neck CT)

1–5

1 in 10 000

Few months
to a few years

Higher doses (chest or abdomen CT,
nuclear cardiogram, cardiac angiogram,barium enema)

5–20

1 in 2000

Few years
to several years

Natural background2.4

1 in 5000—

Procedure
No dose (MRI, ultrasound)

Shrimpton et al. compare some of these reference levels with those that
previously prevailed in Europe. In commenting on their findings, they have many
useful observations to make and conclude in respect of paediatric practice that:“For examinations on children, typical values of the dose descriptors…,
CTDIvol and DLP decrease with decreasing age (and size), whereas thecorresponding effective dose increases. Indeed, effective doses to children
aged 0–1 years from examinations of the head and the chest were typicallyhigher than those for adults” [138].
Other recent national surveys of paediatric CT doses are available, together
with some experience of the potentially positive impact of introducing reference
levels [134, 136, 139]. Table 31 reproduces the recommendations of Verdun et al.
for DRLs in Switzerland. They also usefully compare their findings with recent
work and/or recommendations from the United Kingdom and Germany [138, 140].
It is not clear that, in all cases, like is being compared with like, but nonethelessthe comparisons are reassuring and useful. Additional information on conversionof DLP to effective dose is provided in Appendix V.
A recent large scale multinational study by the IAEA investigated thefrequency of CT examinations of paediatric patients below 15 years of age in
28 countries of Africa, Asia and Eastern Europe, and assessed the magnitude of65

TABLE 30. NATIONAL REFERENCE DOSES FOR COMPUTEDTOMOGRAPHY OF PAEDIATRIC PATIENTS IN THE UNITED KINGDOM(published in 2006 following a 2003 review, compared with European Commission
values from 1999 [138, 139])
Examination

RegionCTDIvol(mGy)aCTDIw(mGy)aUnited Europe United
Kingdom [139] Kingdom
2003
2003
[138]
[138]
Chest (detectionof malignancy)
0–1 year old
5 year old
10 year old

Dose length product(mGy ⋅ cm)a
UnitedKingdom
2003[138]

Europe[139]

Whole
examination
23
20
26

20
30
30

12
13
20

200
230
370

200
400
600

Head trauma (including Post-fossa
non-accidental injury)
Cerebrum
0–1 year oldWholeexamination

35
30
—

—
—
40

35
30
—

—
—
270

—
—
300

Head trauma (including Post-fossa
non-accidental injury)
Cerebrum
5 year oldWholeexamination

50
45
—

—
—
60

50
45
—

—
—
470

—
—
600

Head trauma (including Post-fossa
non-accidental injury)
Cerebrum10 year oldWholeexamination

65
50
—

—
—
70

65
50
—

—
—
620

—
—
750

Note: CTDIw: weighted CT dose index; CTDIvol: CT dose index divided by volume scanned.
aRelates to the 16 cm diameter CT dosimetry phantom.

CT doses. Radiation dose data were available from 101 CT facilities in
19 countries [141].
The results show that, on average, the frequency of paediatric CT
examinations was 20, 16 and 5% of all CT examinations in participating centres
in Africa, Asia and Eastern Europe, respectively. The mean frequencies of
paediatric CT examinations ranged from 0.5 to 38% among different countries.
The survey data indicated a relatively higher paediatric CT frequency in a
majority of African countries than in Asia and Eastern Europe. In the countries
included in this study, the paediatric CT frequency in Asian countries is also
relatively higher than in Eastern Europe. This situation is likely to be due to the66TABLE 31. DIAGNOSTIC REFERENCE LEVELS (mGy FOR COMPUTEDTOMOGRAPHY DOSE INDEX AND mGy ⋅ cm FOR DOSE LENGTH
PRODUCT) FOR DIFFERENT PATIENT GROUPS AND EXAMINATIONSIN SWITZERLAND, GERMANY, THE UNITED KINGDOM AND THE
EUROPEAN UNION (adapted from Verdun [134])
Age group(a)a

Quantity

Examination
Brain

<1
1–5
5–10
10–15

CTDIvol
DLP
CTDIvol
DLP
CTDIvol
DLP
CTDIvol
DLP

Switzerland[134]

Germany

UnitedKingdom

European
Union

20
270
30
420
40
560
60
1000

33
390
40
520
50
710
60
920

30
270
45
470
50
620
65
930

—
300
—
600
—
750
—
—

Chest

<1
1–5
5–10
10–15

CTDIvol
DLP
CTDIvol
DLP
CTDIvol
DLP
CTDIvol
DLP

Switzerland[134]

Germany

UnitedKingdom

European
Union

5
110
8
200
10
220
12
460

3.5
55
5.5
110
8.5
210
6.8
205

12
200
13
230
20
370
14
580

—
200
—
400
—
600
—
—

Abdomen

<1
1–5
5–10
10–15

CTDIvol
DLP
CTDIvol
DLP
CTDIvol
DLP
CTDIvol
DLP

Switzerland[134]

Germany

UnitedKingdom

European
Union

7
130
9
300
13
380
16
500

5
145
8
255
13
475
10
500

20a
170a
20a
250a
30a
500a
14
560

—
—
—
—
—
—
—
—

Note: CTDIvol: CT dose index divided by volume scanned; DLP: dose length product.
For the United Kingdom, adult values were taken for the age group 10–15 years, as values
for this age group were not available in the report.

a67

non-availability of alternative imaging modalities, such as MRI or high resolution
ultrasound, and/or possibly limited experience in justifying CT procedures forchildren.
The CTDIw variations ranged up to a factor of 55 (Africa), 16.3 (Asia) and6.6 (Eastern Europe). The corresponding DLP variations ranged by a factor of 10,
20 and 8, respectively. Eleven CT facilities in six countries were found to use
adult CT exposure parameters for paediatric patients. This single factor has great
implications for the individual dose, collective dose and risk of lifetime radiationinduced cancer. Variations in CTDIw and DLP across countries are notunexpected as similar variations have been presented in earlier studies from anumber of developed countries and are attributable to different techniques used
for CT examinations.
The typical mean CTDIw and DLP values with associated ranges in three
regions are presented in Table 32. In this study, CT equipment dosecharacteristics are reported in terms of CTDIw because the majority of centres
reported this quantity in view of older CT scanners. For those reporting in
CTDIvol, the values of CTDIw were computed using pitch factors.
TABLE 32. MEAN WEIGHTED COMPUTED TOMOGRAPHY DOSE
INDEX AND DOSE LENGTH PRODUCT VALUES WITH ASSOCIATED
RANGES FOR SELECTED PAEDIATRIC COMPUTED TOMOGRAPHY
EXAMINATIONS IN THREE REGIONS [141]Weighted CT dose index (mGy)
RegionChest

Chest —
high resolution

Lumbarspine

AbdomenPelvisAfrica10(4–17.1)

9.8(3.5–14)

14(4.2–14)

8.5(4.2–20)

8.3(4.9–17)Asia

10(5.5–16)

13(5.2–19)13(8.7–18)

14(8.7–20)

14(8.7–18)

Europe8.7(3.3–16)

6.5

11(7.1–22)

9.2(3.5–14)9.3(3.9–14)

Dose length product (mGy ⋅ cm)
Africa153(85–272)137(49–371)201(121–277)180(43–320)131(50–382)Asia

269(134–216)

139(64–260)274(150–397)

413(150–821)

189(150–240)Europe194(76–326)145(96–194)

182(115–385)

246(115–613)

255(82–487)

68

The study indicated a stronger need in many developing countries to justify
CT examinations in children and for their optimization. As an example,
implementation of suitable dose reduction methods and follow-up of the facilities
that use CT exposure parameters for children’s CT examinations were applied in
Sudan and Thailand in consultation with radiologists. Consequently, based on thereported new scan parameters, a CTDIw reduction in the range of 38–50% wasreported for chest CT in Sudan, and 53% for the same type of CT procedure in
Thailand.
This study has established baseline data on the frequency and dose levels in
paediatric CT examinations. This will form a basis for future studies on dosemanagement in paediatric CT examinations. In that sense, the ongoing large scale
paediatric CT dose survey organized by the IAEA is an important step in the
optimization of paediatric CT practice and for promotion and implementation ofdose reduction strategies, while maintaining diagnostic information worldwide.
Furthermore, education and training programmes currently being implemented
by the IAEA in developing countries, along with focused training on radiationdose management organized by the IAEA for participants in the project, provide
key resources directed at increased awareness of radiation dose management
methods in CT.

6.4. SPECIAL TECHNIQUES IN COMPUTED TOMOGRAPHY
6.4.1.

Computed tomography interventions

Once a diagnostic scan has been performed, the CT dose used for theinterventional procedure can be reduced markedly. Repeated imaging has to belimited to the small area of interest directly involved in the procedure. Where
possible, a single slice may be used.
6.4.2.

Cone beam dental computed tomography

CT based systems are finding significant application in dental practice, andintensive study of the requirements for justification is necessary. These and otherdevelopments are the subject of the SEDENTEXCT EC project [142]. The
principles for use of dental cone beam CT have been set out by the European
Academy of Dental and Maxillofacial Radiology in a consensus document fromwhich an extract is provided in Table 33 [142]. Much of this guidance deals withjustification issues but training and optimization issues are also emphasized.

69

TABLE 33. USE OF DENTAL CONE BEAM COMPUTED TOMOGRAPHY[142]
Cone beam CT examinations need not be carried out unless a history and clinical examination
have been performed.
Cone beam CT examinations are required to be justified for each patient to demonstrate that thebenefits outweigh the risks.
Cone beam CT examinations need to potentially add new information to aid the patient’s
management.
Cone beam CT ought not to be repeated ‘routinely’ on a patient without a new risk–benefit
assessment having been performed.
When accepting referrals from other dentists for cone beam CT examinations, the referring
dentist needs to supply sufficient clinical information (results of a history and examination) toallow the cone beam CT practitioner to perform the justification process.
Cone beam CT need only be used when the question for which imaging is required cannot beanswered adequately by lower dose conventional (traditional) radiography.
Cone beam CT images need to undergo a thorough clinical evaluation (‘radiological report’) of
the entire image data set.
Where it is likely that the evaluation of soft tissues will be required as part of the patient’s
radiological assessment, the appropriate imaging needs to be conventional medical CT or MRI,
rather than cone beam CT.
Cone beam CT equipment needs to offer a choice of volume sizes, and examinations need to use
the smallest volume that is compatible with the clinical situation if this provides less radiationdose to the patient.
Where cone beam CT equipment offers a choice of resolution, the resolution compatible withadequate diagnosis and the lowest achievable dose needs to be used.
A quality assurance programme needs to be established and implemented for each cone beam
CT facility, including equipment, techniques and quality control procedures.
Aids to accurate positioning (light beam markers) always need to be used.
For dento-alveolar cone beam CT images of the teeth, their supporting structures, and the
mandible and the maxilla up to the floor of the nose (e.g. 8 cm × 8 cm or smaller fields of view),a clinical evaluation (‘radiological report’) needs to be undertaken by a specially trained dental
and maxillofacial radiologist or, where this is impracticable, an adequately trained generaldental practitioner.
For non-dento-alveolar small fields of view (e.g. temporal bone) and all craniofacial cone beam
CT images (fields of view extending beyond the teeth, their supporting structures, the mandible,
including the temporomandibular joint, and the maxilla up to the floor of the nose), a clinicalevaluation (‘radiological report’) needs to be undertaken by a specially trained dental andmaxillofacial radiologist or by a clinical radiologist (medical radiologist).

70

7. NUCLEAR MEDICINE
Nuclear medicine investigations are an important component of the overallimaging armamentarium used in paediatric imaging. The general provisions forpatient and staff safety in nuclear medicine are not addressed in this section asthese are beyond the scope of this publication, and are widely available frommany sources [4, 143, 144]. This section is limited to aspects of safety in nuclear
medicine that have specific paediatric applications. Some additional practicalinformation is provided in Appendix VI.

7.1. JUSTIFICATION IN NUCLEAR MEDICINE
As with other imaging modalities, nuclear medicine studies are required tobe rigorously justified. Large individual and population doses arising from
nuclear medicine activity in some countries are, at least in part, attributable tosome overutilization and to questionable referral patterns. Alternative modalities,
such as ultrasonography (e.g. in the assessment and follow-up of renal
abnormalities) and MRI, have to be considered (e.g. in assessing bone lesions
which involve the bone marrow and surrounding soft tissues). However, nuclear
medicine studies, including renography and bone scans, continue to be useful andare regularly performed in children.
Some advice on nuclear medicine referrals is available in Ref. [28]. The
advice of earlier sections needs to be followed in relation to information provided
to the patient, development of local protocols for referral, clinical audit ofjustification, and communication with the patient, their carers and comforters,
their parents and the referring physician.

7.2. OPTIMIZATION AND DOSE REDUCTION IN NUCLEAR MEDICINEThe radiopharmaceutical activity given to paediatric patients has to be theminimum amount necessary to ensure a satisfactory examination. High activity(which does not result in improved diagnostic accuracy or sensitivity) or low
activity (which does not permit an adequate scan) are both unacceptable, as they
are both likely to give rise to unnecessary radiation exposure.
A work group composed of paediatric nuclear medicine physicians, medical
radiation technologists and medical physicists, representing the Society of
Nuclear Medicine, the Society for Paediatric Radiology and the American
College of Radiology, recently issued consensus guidelines for administered71

radiopharmaceutical activities in children and adolescents [10]. The guidelines
were based on a survey conducted at 13 paediatric hospitals in North America
indicating that administered radiopharmaceutical activities in children varied
widely. The purpose of the work was to fulfil the above mentioned goals of
diagnostic nuclear medicine procedures.
In practice, paediatric activity is estimated based on commonly used adultactivities, corrected for body weight or body surface area. These activities are
generally a good guide for children over 1 year of age [145–148]. Effective dose
for a paediatric patient will depend upon the method used for adjustment ofradionuclide activity (body surface area or body weight). If the body weightapproach is used, the effective dose for children will be comparable to that for an
adult [1]. Effective doses from diagnostic nuclear medicine procedures are given
in Table 34.
The DRL in nuclear medicine is specified as the activity administered to thechild. Table 35 illustrates a set of DRLs used in Ireland for sevenradiopharmaceuticals for children of various ages, and for adults. These areconsistent with practice elsewhere in Europe. These activities can be comparedwith the often higher median activity per kilogram used in the USA (Table 36),
based on a survey of a number of hospitals in the USA. No DRLs focused on the
nuclear medicine component of positron emission tomography (PET)examinations have yet been developed. In the case of PET/CT, the guidelines for
CT also have to be followed [149].
Care needs to be taken with the scanning protocol in optimization for
paediatric studies. Where appropriate, use needs to be made of electronicmagnification, converging collimators for small organs, high sensitivity
collimators when there is an advantage in using them, and appropriate choice ofradiopharmaceuticals (e.g. MAG3 instead of DTPA for dynamic renal scans).
From a practical standpoint, there are important considerations particular to
infants and small children. The infant or child needs to be well hydrated, andfrequent diaper changes are necessary for babies and/or toddlers. Those dealing
with infants, and carers and comforters of infants need to have a good knowledgeof the radionuclide involved, its half-life, the biodistribution of theradiopharmaceutical form used in the infant and any other pertinent physiologicalfactors.
Positioning of the patient is important during nuclear medicine imaging.
Immobilization devices, such as sandbags, pillows, etc., are commonly used.
Viewing television or a video during the examination often helps to distract
children. In some cases, sedation is required. This may be the case when lengthy
procedures, such as single photon emission CT (SPECT), are performed. The
type and level of sedation as well as the activity used need to be determined inconsultation with the referring clinician.

72

TABLE 34. EFFECTIVE DOSES FROM TYPICAL NUCLEAR MEDICINEPROCEDURES FOR PAEDIATRIC PATIENTS [1]Procedure utilizing:
F-18 FDG

Effective dose (mSv/MBq)
15 year old

10 year old

5 year old

1 year old

0.025

0.036

0.050

0.095

Ga-67 citrate

0.130

0.200

0.330

0.640

I-123 sodium iodide (0% uptake)

0.016

0.024

0.037

0.037

I-123 sodium iodide (5% uptake)

0.053

0.080

0.150

0.290

I-123 sodium iodide (15% uptake)

0.110

0.170

0.350

0.650

I-123 sodium iodide (25% uptake)

0.170

0.260

0.540

1.000

I-123 sodium iodide (35% uptake)

0.230

0.350

0.740

1.400

I-123 sodium iodide (45% uptake)

0.290

0.440

0.940

1.800

I-123 sodium iodide (55% uptake)

0.350

0.530

1.100

2.100

In-111 pentatreotide

0.071

0.100

0.160

0.280

In-111 white blood cells

0.836

1.240

1.910

3.380

Tc-99m HIDA

0.021

0.029

0.045

0.100

Tc-99m DMSA

0.011

0.015

0.021

0.037

Tc-99m HMPAO

0.011

0.017

0.027

0.049

Tc-99m MAA

0.016

0.023

0.034

0.063

Tc-99m MDP

0.007

0.011

0.014

0.027

Tc-99m MAG3

0.009

0.012

0.012

0.022

Tc-99m ECD

0.014

0.021

0.032

0.060

Tc-99m DTPA

0.006

0.008

0.009

0.016

Tc-99m pyrophosphate

0.007

0.011

0.014

0.027

Tc-99m red blood cells

0.009

0.014

0.021

0.039

Tc-99m sestamibi (rest)

0.012

0.018

0.028

0.053

Tc-99m sestamibi (stress)

0.010

0.016

0.023

0.045

Tc-99m sodium pertechnetate

0.017

0.026

0.042

0.079

Tc-99m sulphur colloid

0.012

0.018

0.028

0.050

Tc-99m tetrofosmin (rest)

0.010

0.013

0.022

0.043

Tc-99m tetrofosmin (stress)

0.008

0.012

0.018

0.035

Tc-99m thallous chloride

0.293

1.160

1.500

2.280

Note: DMSA: dimercaptosuccinic acid; DTPA: diethylenetriaminepentaacetic acid; ECD: ethyl
cysteinate dimer; FDG: fluorodeoxyglucose; HIDA: hepatobiliary iminodiacetic acid;
HMPAO: hexamethylpropyleneamine oxime; MAA: macroaggregate of albumin;
MAG3: mercaptoacetyltriglycine; MDP: methylene diphosphonate.

73

TABLE 35. PAEDIATRIC DIAGNOSTIC REFERENCE LEVELS (MBq) FOR
COMMONLY PERFORMED DIAGNOSTIC PROCEDURES [145]Paediatric diagnostic reference level (MBq)Radiopharmaceutical

Newborn 1 year old 5 year old 10 year old 15 year old Adult(5 kg)(10.5 kg) (19.5 kg)(33 kg)(64.5 kg) (70 kg)

Tc-99m phosphonates(bone)

43

90

167

283

549

600

Tc-99m DMSA

15

15

28

47

91

100

Tc-99m DTPA

20

33

61

104

201

220

Tc-99m MAG3

15

15

28

47

91

100

Tc-99m pertechnetate
thyroid

10

12

22

38

73

80

Tc-99m pertechnetate
Meckel’s

28

58

107

182

352

385

Note: DMSA: dimercaptosuccinic acid; DTPA: diethylenetriaminepentaacetic acid; MAG3:
mercaptoacetyltriglycine.

Stabin et al. present effective and absorbed dose estimates for children ofdifferent ages, for different nuclear medicine procedures, using standard medical
internal radiation dose methodology [150]. Effective doses per unit of administeredradiopharmaceutical (mSv/MBq) have also been calculated using five paediatricphantoms for a number of radiopharmaceuticals commonly used in children.
Values of effective dose resulting from the application of the weight/surface
area schedules of administered radiopharmaceutical proposed by the paediatrictask group of the European Association of Nuclear Medicine are also available.
Although some values of effective dose exceed 10 mSv for the surface areaschedule, the majority are less than 5 mSv [151].
As mentioned in Section 2.5, arrangements to deal with the unintended
administration of activity to patients are required. This may be more sensitive inpaediatric nuclear medicine than in radiology, even when the dose is lower. Good,
well conceived and well tested systems to provide fail-safe protection against
misadministration need to be part of the operational policy of every department.
When a paediatric patient receives the incorrect amount of radiopharmaceutical or when the incorrect radiopharmaceutical is administered, thisneeds to be reported within the hospital and investigated, as discussed in Section
2.5, with a view to implementing corrective actions to reduce the likelihood ofrecurrence of such an incident. The patient and/or the parent and/or guardian
and/or carers and comforters have to be informed. In some countries, it is also
mandatory to report incidents of this type to the regulatory authorities or medical
authorities (Section 2.5).

74

TABLE 36. MEDIAN ACTIVITY PER KILOGRAM OF BODY WEIGHTINJECTED INTO PAEDIATRIC PATIENTS (adapted from Ref. [146])
Radionuclide and marker

Median activity (MBq/kg)

Tc-99m DMSA

2.22

Tc-99m MAG3

5.55

Tc-99m MDP

11.10

Tc-99m DISIDA

2.78

I-123 MIBG

5.55

Tc-99m NaTcO4 for Meckel’s

5.18

I-123 NaI for thyroid

0.10

Tc-99m ECD or HMPAO

10.55

Tc-99m MIBI

12.95

Tc-99m MAA

1.85

Tc-99m ultratag for gastrointestinal

8.33

Tc-99m ultratag for multiple gated acquisition

8.14

Tc-99m denatured red blood cells

2.22

Ga-67 inflammatory disease

1.85

Ga-67 tumour imaging

4.07

F-18 FDG

5.37

Note: DISIDA: di-isopropyliminodiacetic acid; DMSA: dimercaptosuccinic acid; ECD: ethyl
cysteinate dimer; FDG: fluorodeoxyglucose; HMPAO: hexamethylpropyleneamine oxime;
MAA: macroaggregate of albumin; MAG3: mercaptoacetyltriglycine; MDP: methylene
diphosphonate; MIBG: metaiodobenzylguanidine; MIBI: methoxyisobutylisonitrile.

75

8. SUMMARY AND CONCLUSIONSThe context for this report is the increasing use of paediatric radiology,
increasing doses from individual examinations and increasing concern about theresulting potential harm that may arise to children. It is, therefore, important toemphasize that most paediatric radiology is necessary and of great benefit to thechildren examined.
Sections 1–7 establish the need to attend to the features of radiology ofyounger persons that distinguish it from adult radiology. In addition, they provide
a considered range of tools to deal with the problems arising from thesedifferences. The special requirements that arise apply to all aspects of theradiation protection system, including justification with its associated processes,
and the multifaceted task of optimization, including the use of DRLs and dose
constraints. All of these help guide those involved in service delivery towards
good practice. The radiological techniques to which these approaches are applied
include all radiology, including general screen film and DR, dental and mobile
radiography, fluoroscopy, interventional procedures and CT.
The requirement for justification has been emphasized as some workers
estimate that a significant fraction of paediatric examinations are not justified.
Until recently, it was felt that there was little that might be done to assess andfacilitate justification in practice. However, throughout this publication, a numberof tools are proposed and offered to facilitate justification. These include:— Use of evidence based referral guidelines and local protocols, whereavailable;— Use of clinical audit of justification (including appropriateness of
examinations).
These will ensure that the justification protocols and/or processes are wellformulated. Examinations will only be conducted when appropriate andnecessary, and due regard will be paid to an appropriate process for providing
information to the patient and family. When available, alternative techniques suchas ultrasound and MRI will be used. Close attention will be paid to previous
procedures and the information available from the referring practitioner, thepatient and their family.
With respect to optimization, many initiatives are necessary and aredetailed in the preceding sections on particular techniques. The following core
points apply generically to almost all of the techniques:76

— All persons directing and conducting medical exposure of children,
including radiologists and technologists, have to have received recognizededucation and training in their discipline, including in radiation protection,and specialist training in its paediatric aspects.
— Care needs to be taken with procurement of equipment to ensure that it isspecified, supplied and acceptance tested in accordance with international
technical standards. A team approach to each stage needs to be taken, andmay involve a medical physicist. The specification needs to explicitly
include the relevant paediatric features.
— All examinations need to be conducted using ‘child-sized’ protocols and/or
exposures, which have been developed using a team approach involving
radiological medical practitioners, medical radiation technologists, medical
physicists, supplier application specialists and engineers.
— Additional training specific to each item of equipment, using the teamapproach, is essential to ensure that all staff will adopt and continue to use
the ‘child-sized’ protocols. Protocols for repeat and/or confirmation
procedures need to be reduced to the views essential for the management of
the patient.
— Practice in a department may be audited periodically with respect to anindex for patient dose. This needs to be compared with local, regional or
national DRLs. It is necessary to be aware of the DRLs appropriate to theregion.
— An ongoing quality assurance programme, using a team approach, needs tobe employed and may be managed as part of a clinical audit programme.
— Dose indication is essential on interventional, CT and fluoroscopy
equipment, and is desirable on other equipment.
— There is a serious lack of good up to date data on reference doses in all areasof paediatric radiology, including high dose areas such as CT andinterventional radiology. The lack also extends to lower dose areas such asradiography and dental examinations.
— It is necessary to become aware of the possibility of unnecessarily or
inadvertently using high doses, particularly with CT, interventional
radiology and all digital systems. It is necessary to become informed on
how to prevent this.
— Carers and comforters, and those who help restrain children during
procedures are not to be members of hospital or clinic staff. They may, forexample, be members of the patient’s family, and may knowingly andwillingly offer their service within a medical framework to which an age
related dose constraint is applied.
— Collimation needs to be tight, and additional shielding of sensitive areas(e.g. breast, gonads, thyroid, eyes) has to be employed where practicable.

77

— When ‘child-sized’ protocols have not been explicitly supplied, developed
and/or verified as appropriate, manual exposures need to be used.
— The image receptor normally has to be as close to the patient as possible andthe X ray tube has to be as far away as is practical for the protocol being
followed.
— As a general rule, anti-scatter grids need not be used with small children.
— Where practicable, all X ray examinations need to be performed on fixedunits in the relevant department. The use of mobile X ray units needs to belimited to those patients who cannot be moved to a fixed X ray unit.
— For female children who are or may be pregnant, special precautions arenecessary.
— Staff are not to be in the room when exposures are ongoing unless this isabsolutely necessary. Generally, this is only the case during interventions
and when conducting fluoroscopy. Staff who have to be in the room in suchcircumstances require additional special training.
The particular requirements for each modality are detailed in theappropriate section.
Finally, while the above considerations are valuable in initiating theprocesses of justification and optimization as envisaged in the BSS, they are notcomprehensive. Much remains to be done in further resolving the appropriate
referral patterns, optimization of technique and developing guidance or reference
levels in paediatric radiology in a fast changing technology. The advice presented
here will inform the recommendations in the revised Safety Guide [6], as well as
assist States in complying with the requirements of the BSS.

78

Appendix I
BIOLOGICAL EFFECTS OF RADIATION IN CHILDREN

The biological effects of ionizing radiation in children depend on theirradiosensitivity, their life expectancy and their radiation exposure. In practice, atthe same effective dose, the biological effects and lifetime risks can be expected
to be higher in a child than in an adult [11, 13, 14]. However, the extent of theincrease is not definitively established and there is a lack of agreement on how
best to present it.
Organs and tissues are distributed differently and are more susceptible toradiation during childhood. A CT examination of the lower extremities will, inbone marrow, encounter almost exclusively fatty marrow in an adult. In a child, inthe same examination, a significant proportion of the red marrow will be exposed
and is, therefore, a much greater cause for concern [9].
It is also suggested that at the cellular and subcellular levels, proliferation
during growth periods is likely to be associated with increased susceptibility. As
most malignant tumours become manifest many years after exposure, adultpatients may have died from other causes before induced cancers are expressed.
Children, because of their longer life expectancy, have a higher chance of being
alive at the time of tumour presentation.
A framework for dealing with the risk of incidence and fatality fromradiation induced cancers is provided by the ICRP and is broadly based on theapproach to biological effects of radiation set out in the BEIR Report [11–14].
The combined impact of these reports is to indicate a substantial increase inlifetime risk among those irradiated during childhood. There are also substantial
gender differences.
Attempts have been made to summarize the data and produce a single figure
defining the relative sensitivities of children as opposed to adults. The values tend
to vary from unity up to about four depending on age, and the values cited in theliterature for increases in the impact expected in paediatric patients are usually
two to three. The net impact of these assessments is a view that there are
significant cancer risks associated with some forms of paediatric radiology,
particularly when vigorous measures for justification and optimization are nottaken [16, 152].
The following considerations may help to illustrate the problem. In infant
girls, the risk may be up to ten times that for an adult. The risk is higher for girls
than for boys. The overall fatal risk coefficient is approximately 5% per sievert
for the whole population. The coefficient may only be 3% for the subset of the
population over 50 but can be as high as 15% for younger children [153, 154].

79

Thyroid, lung, breast tissue and bone marrow are characterized by higher
radiation sensitivity during childhood. A breast dose of 10 mGy to a female,received before 35 years of age, will increase the spontaneous breast cancer rateby 14% [153, 155, 156]. Scoliosis patients have a larger number of X rays when
they are children or young adults. Table 37, from a study performed on a cohortof almost 5000 scoliosis patients, suggests that at relatively low doses excess
breast cancer deaths can occur. It is thought this could possibly be because theexposure took place at a time when the breast appears to be especially sensitive toradiation [157].
Children are also sometimes further at risk because of unnecessary
examinations and the increased dose received in examinations [16, 152]. For
example, as stated in many places in the text, children still continue to receive
higher doses because of inappropriate protocols or unsuitable AEC systems,
particularly in CT.
In addition to these unwarranted increases, there are circumstances in which
the dose to children may need to be increased. For example, they have thinner
layers of abdominal visceral fat and, thus, lack the associated natural contrast
usually available in adults. As a result, increased radiosensitivity is compoundedby additional radiation, some necessary and some unnecessary.

TABLE 37. BREAST CANCERMORTALITY AND DIAGNOSTIC
X RAYS FOR SCOLIOSIS [157]4822 exposed, 644 not exposed
Mean age at exposure: 10.6 years
Mean dose: 0.11 Gy
70 observed cancers
35.7 expected80Appendix II
EXTRACT FROM THE EUROPEAN COMMISSION’S REFERRALGUIDELINES FOR IMAGING

A representative version of the referral guidelines for paediatric radiology
published by the EC in 2008 is adapted in Table 38 [28, 29]. They are part of alarger document dealing with guidelines for diagnostic radiology and nuclear
medicine. The 2008 published version is based on material developed around
2003, and is already under revision. These guidelines and/or criteria and theirapplication in practice are further discussed in the subsections of Sections 2 and4–7 on justification. Care has to be taken with their application in practice tomake sure that they are well adapted to the time and place in which they are used.
Other examples of guidance include the appropriateness criteria developed by theAmerican College of Radiology, and the referral guidelines produced in the
United Kingdom [15, 17, 30, 31]. There is much variability in the extent to whichthese tools are implemented in practice.
TABLE 38. REFERRAL GUIDELINES FOR PAEDIATRIC IMAGES(adapted from Ref. [28])Clinical problem

Investigation(dose)aRecommendation(grade)b

Comment

PAEDIATRICS
X ray irradiation needs to be minimized in children, especially those with long term problems
Central nervous system
Indicated (C)Definitive examination for all
malformations and avoids X ray irradiation.
Ultrasound needs to be considered inneonates. 3-D CT may be needed for bone
anomalies.

Congenital
disorders

MRI (0)Abnormal headappearance:hydrocephalus,
odd sutures

Ultrasound indicated where anterior
Ultrasound (0) Indicated (B)fontanelle is open and where sutures are
SkullSpecializedradiography (I) investigation (C) closed and/or closing. MRI indicated forolder children. (CT may be appropriate if
MRI not available.)

Epilepsy

Skull
Not routinely
radiography (I) indicated (B)Poor yield.

81

TABLE 38. REFERRAL GUIDELINES FOR PAEDIATRIC IMAGES(adapted from Ref. [28]) (cont.)
Clinical problem

Investigation(dose)aRecommendation(grade)b

Comment

MRI (0)or nuclear
medicine (II)MRI usually more appropriate than CT.
Specialized
investigation (C) Ictal and inter-ictal SPECT also used to
identify focus before surgery.

Deafness inchildrenCT (II)MRI (0)Both CT and MRI may be necessary
Specialized
investigation (C) in children with congenital andpost-infective deafness.

Hydrocephalus:
shunt malfunction

Plain
Indicated (B)radiography (I)Plain radiography needs to include thewhole valve system.

Ultrasound (0)or MRI (0)Ultrasound if practical; MRI in older
children (or CT if MRI unavailable).
Nuclear medicine used to evaluate shunt
function.

Indicated (B)Developmental
delay: cerebral
palsy

Cranial MRI (0) Specialized
investigation (B)Headaches

Skull
Not indicatedradiography (I) routinely (B)MRI (0)or CT (II)If persistent or associated with clinicalsigns, refer for specialized investigations.

In children, MRI is preferable if available
Specialized
investigation (B) because of the absence of X ray irradiation.

Sinus plain
Not routinely
radiography (I) indicated (B)Not indicated before 5 years of age as thesinuses are poorly developed; mucosal
thickening can be a normal finding inchildren. A single under-tilted otitis media
view may be more appropriate than thestandard otitis media view, depending on
the child’s age.

Torticollis without
traumaPlain
Not indicatedradiography (I)Deformity is usually due to spasm with nosignificant bone changes. If persistent,
further imaging (e.g. CT) may be indicatedfollowing consultation.

Back or neck pain

Plain
Indicated (B)radiography (I)Back pain without a cause is uncommon inchildren. Follow-up is needed if infection issuspected.

Sinusitis

Neck and spine82

TABLE 38. REFERRAL GUIDELINES FOR PAEDIATRIC IMAGES(adapted from Ref. [28]) (cont.)
Clinical problem

Spina bifida
occultaInvestigation(dose)aRecommendation(grade)b

Comment

Nuclearmedicine (II)When pain continues and XRs are normal.
Specialized
investigation (B) Useful in painful scoliosis.

MRI (0)

MRI defines spinal malformations andSpecialized
investigation (B) excludes associated thecal abnormality.
MRI can also demonstrate juvenile disclesions.

Plain
Not indicatedradiography (I) routinely (B)Hairy patch, sacral Plain
Not indicateddimpleradiography (I) routinely (B)A common variation and not in itself
significant (even in enuresis). However,neurological signs would require
investigation.
May be helpful in older children.

Musculoskeletal examinations
Non-accidental
Plain
Indicated (B)injury: child abuse radiography (I)of affected parts

Nuclearmedicine (II)Indicated (B)Local policies will apply; close clinicaland/or radiological liaison essential.
Skeletal survey for those under 2 yearsof age after clinical consultation. May
occasionally be required in the older child.
CT/MRI of brain may be needed, even in
the absence of cranial apparent injury.
Sensitive for occult spine and/or rib
fracture.

Limb injury:
opposite side forcomparison

Plain
Not indicatedradiography (I) routinely (B)Radiological advice needs to be sought.

Short stature,
growth failure

Plain
Indicated atradiography (I) appropriate
for bone age
intervals (B)

2–18 years: left (or non-dominant) hand
and/or wrist only. Premature infants andneonates: knee (specialized investigation).
May need to be supplemented with askeletal survey and MRI for hypothalamus
and pituitary fossa (specialized
investigations).

83

TABLE 38. REFERRAL GUIDELINES FOR PAEDIATRIC IMAGES(adapted from Ref. [28]) (cont.)
Clinical problem

Investigation(dose)aRecommendation(grade)b

Comment

Irritable hip

Ultrasound (0)Indicated (B)Ultrasound will delineate effusions which
can be aspirated for diagnostic andtherapeutic purposes. Plain radiography
can be delayed but has to be consideredwhen the symptoms are persistent. Nuclear
medicine or MRI need to be consideredwhen Perthes’ disease is suspected andplain radiography is normal.

Limp

Plain
radiography
pelvis (I)Indicated (C)Gonad protection is routinely used unlessshields will obscure the area of clinicalsuspicion. If slipped epiphyses is likely,
lateral plain radiography of both hips isneeded.

Ultrasound (0)or nuclear
medicine (II)or MRI (0)According to local policy, expertise andSpecialized
investigation (B) availability.

Focal bone pain

Indicated (B)Plainradiography (I)andultrasound (0)Plain radiography may be normal initially.
Ultrasound can be helpful, particularly inosteomyelitis.

Nuclearmedicine (II)or MRI (0)Increasing use of MRI here.
Specialized
investigation (B)Clicking hip —dislocation

Ultrasound (0)Indicated (B)Plain radiography may be used tosupplement ultrasound examination orwhere expertise is not available. Plain
radiography is indicated in the older infant.

Osgood–Schlatter’s diseasePlainradiographyknee (I)

Not indicatedroutinely (C)Although bony radiological changes arevisible in Osgood–Schlatter’s disease, theseoverlap with normal appearances.
Associated soft tissue swelling needs to beassessed clinically rather thanradiographically.

84

TABLE 38. REFERRAL GUIDELINES FOR PAEDIATRIC IMAGES(adapted from Ref. [28]) (cont.)
Clinical problem

Investigation(dose)aRecommendation(grade)b

Comment

Cardiothoracic examinations
Acute chest
infection

Chest
Not indicatedradiography (I) routinely (C)Initial and follow-up films are indicated in
the presence of persisting clinical signs or
symptoms, or in the severely ill child. The
need for chest radiography is considered infever of unknown origin. Children may
have pneumonia without clinical signs.

Recurrent
productive coughChest
Not indicatedradiography (I) routinely (C)Children with recurrent chest infection tend
to have normal chest radiographs (apartfrom bronchial wall thickening). Routine
follow-up chest radiography not indicatedunless collapse present on initial chest
radiography. Suspected cystic fibrosis
requires specialist referral.

Inhaled foreign
body (suspected)

Chest
Indicated (B)radiography (I)History of inhalation often not clear.
Bronchoscopy is indicated, even in thepresence of a normal chest radiograph.
Nuclear medicine/CT may be helpful toshow subtle air trapping. Wide variation in
local policy about expiratory films,
fluoroscopy, CT and nuclear medicine(ventilation scintigraphy).

WheezeChest
Not indicatedradiography (I) routinely (B)Children with asthma usually have anormal chest radiograph apart frombronchial wall thickening. Chest
radiography indicated for sudden
unexplained wheeze — may be due toinhaled foreign body (above).

Acute stridor

Plainradiographyneck (I)

Epiglottitis is a clinical diagnosis but
foreign body needs to be considered(above).

Heart murmur

Chest
Not indicatedradiography (I) routinely (C)Not indicatedroutinely (B)Specialist referral may be needed; cardiac
ultrasound may often be indicated.

85

TABLE 38. REFERRAL GUIDELINES FOR PAEDIATRIC IMAGES(adapted from Ref. [28]) (cont.)
Clinical problem

Investigation(dose)aRecommendation(grade)b

Comment

Gastrointestinal examinations
Intussusception

Abdominal
Indicated (C)radiography (II)Local policies require close paediatric,
radiological and surgical liaison. Where
expertise is available, both ultrasound andcontrast enema (air or barium) can confirm
diagnosis and guide reduction.

Further imaging Specialized
investigation (B)Swallowed foreign Abdominal
Not indicatedbodyradiography (II) routinely (C)Except for sharp or potentially poisonous
foreign bodies, e.g. batteries.

Chest
Indicated (C)radiography (I)(including neck)If there is doubt whether the foreign bodyhas passed, an abdominal radiograph after 6
days may be indicated.

Abdominal
Not indicatedradiography (II) routinely (C)Ultrasound may be used as initialinvestigation but CT is more specific,
particularly in visceral trauma. Plain
radiography may show bone injury insevere trauma. The principles for theinvestigation of major trauma in children
are similar to those in adults.

Minor trauma to
abdomen

Projectile vomiting Ultrasound (0)Indicated (A)Ultrasound can confirm the presence ofhypertrophic pyloric stenosis, especiallywhere clinical findings are equivocal.

Recurrent
vomiting

Not indicatedroutinely (C)This symptom covers a wide range from
obstruction in the neonatal period to reflux,
posseters and children with migraine.
Ultrasound may be helpful to confirm
malrotation. However, uppergastrointestinal contrast studies may be
indicated to exclude malrotation even withnormal abdominal plain radiography.
Contrast studies in neonates need to beundertaken as a specialized investigation.
Nuclear medicine needs to be considered
for gastric emptying and gastrooesophageal reflux.

86

Upper gastrointestinal
contrast studyTABLE 38. REFERRAL GUIDELINES FOR PAEDIATRIC IMAGES(adapted from Ref. [28]) (cont.)
Clinical problem

Investigation(dose)aRecommendation(grade)b

Comment
Early (<10 weeks) and prompt
investigation is essential. The absence ofdilatation in the intrahepatic bile duct does
not exclude an obstructive cholangiopathy.

Persistent neonatal Ultrasound (0)jaundice
Nuclearmedicine (II)Indicated (B)Indicated (B)Rectal bleeding

Nuclearmedicine (II)If Meckel’s diverticulum is a possibility,
Specialized
investigation (B) nuclear medicine needs to be used first.
Small bowel contrast studies may also benecessary. Nuclear medicine is also usefulfor investigation of inflammatory bowel
disease. Endoscopy is preferable to barium
enema for assessment of polyps andinflammatory bowel disease. Ultrasoundcan be used to diagnose duplication cysts.

Constipation

Abdominal
Not indicatedradiography (II) routinely (C)Many normal children show extensive
faecal material; it is impossible to assess
the significance of radiological signs.
Nevertheless, abdominal radiography canhelp specialists in refractory cases.

Contrast enema Not indicatedroutinely (B)If Hirschsprung’s disease is suspected,
specialist referral plus biopsy is preferred toradiological studies.

Ultrasound (0) Indicated (B)and abdominal
radiography (II)If malignancy is suspected, further imaging
needs to be performed in a specialized
centre.

Palpableabdominal and/or
pelvic mass

Uroradiology examinations
Enuresis

Imaging

Not indicatedroutinely (B)Ultrasound and urodynamic studies may beneeded in cases of persistent enuresis.

Continuous
wetting

Ultrasound (0)Indicated (B)Both examinations may be needed toevaluate the duplex system with an ectopic
ureter.

Intravenous
urogram (II)Indicated

87

TABLE 38. REFERRAL GUIDELINES FOR PAEDIATRIC IMAGES(adapted from Ref. [28]) (cont.)
Clinical problem

Investigation(dose)a

Impalpable testis

Ultrasound (0)Indicated (B)To locate inguinal testis. MRI may be
helpful to locate an intra-abdominal testis
but increasingly laparoscopy is theinvestigation of choice.

Antenatal
diagnosis ofurinary tract
dilatation

Ultrasound (0)Indicated (B)Local protocols need to be established.
Mild dilatation can normally be monitored
by ultrasound. Low threshold for specialist
referral.

Proven urinary
tract infection

Imaging
ultrasound (0)or nuclear
medicine (II)orcystography

There is wide variation in local policy.
Specialized
investigations (C) Much depends on local technology andexpertise. Most patients may remain on
prophylactic antibiotics pending the resultsof investigations. The age of the patientalso influences decisions. There is muchcurrent emphasis on minimizing radiation
dose; hence, abdominal radiography is notindicated routinely (calculi rare). Expert
ultrasound is the key investigation in all
imaging strategies at this age. Thereafter,
nuclear medicine provides data about renal
structure (dimercaptosuccinic acid) and has
virtually replaced the intravenous urogram
here. Nuclear medicine will establish
function, exclude obstruction and can also
be used for cystography (direct or indirect)
to show reflux. Formal direct plainradiography cystography is still needed in
the young male patient (e.g. <2 years ofage) where delineation of the anatomy (e.g.
urethral valves) is critical.

a
b

88

Recommendation(grade)b

Comment

Effective dose classes: 0 (0 mSv); I (<1 mSv); II (1–5 mSv); III (5–10 mSv); IV (>10 mSv).
A: randomized controlled trials, meta-analyses, systematic reviews; B: robust experimental or
observational studies; C: other evidence where the advice relies on expert opinion and has theendorsement of respected authorities.

APPENDIX III
EXPLANATION OF TERMS AND ADDITIONAL DOSE DATA

III.1. EXPLANATION OF TERMS
Definitions of terms for health professionals and related information areprovided below from the BSS [2].
medical physicist. A health professional, with specialist education and training
in the concepts and techniques of applying physics in medicine, andcompetent to practise independently in one or more of the subfields(specialties) of medical physics.
Note: Competence of persons is normally assessed by the State by having aformal mechanism for registration, accreditation or certification of medical
physicists in the various specialties (e.g. diagnostic radiology, radiation
therapy, nuclear medicine). States that have yet to develop such a mechanism
would need to assess the education, training and competence of any
individual proposed by the licensee to act as a medical physicist and to
decide, on the basis either of international accreditation standards or
standards of a State where such an accreditation system exists, whether suchan individual could undertake the functions of a medical physicist, within therequired specialty.
medical radiation technologist. A health professional, with specialist educationand training in medical radiation technology, competent to carry out
radiological procedures, on delegation from the radiological medical
practitioner, in one or more of the specialties of medical radiation technology.
Note: Competence of persons is normally assessed by the State by having aformal mechanism for registration, accreditation or certification of medical
radiation technologists in the various specialties (e.g. diagnostic radiology,
radiation therapy, nuclear medicine). States that have yet to develop such amechanism would need to assess the education, training and competence of
any individual proposed by the licensee to act as a medical radiation
technologist and to decide, on the basis either of international standards or
standards of a State where such a system exists, whether such an individual
could undertake the functions of a medical radiation technologist, within therequired specialty.

89

radiation protection officer. A person technically competent in radiation
protection matters relevant for a given type of practice who is designated by
the registrant, licensee or employer to oversee the application of relevant
requirements.
radiological medical practitioner. A health professional with specialist educationand training in the medical uses of radiation, who is competent to perform
independently or to oversee procedures involving medical exposure in agiven specialty.
Note: Competence of persons is normally assessed by the State by having aformal mechanism for registration, accreditation or certification ofradiological medical practitioners in the given specialty (e.g. radiology,
radiation therapy, nuclear medicine, dentistry, cardiology). States that have
yet to develop such a mechanism need to assess the education, training andcompetence of any individual proposed by the licensee to act as aradiological medical practitioner and to decide, on the basis either ofinternational standards or standards of a State where such a system exists,
whether such an individual can undertake the functions of a radiological
medical practitioner, within the required specialty.
referring medical practitioner. A health professional who, in accordance withnational requirements, may refer individuals to a radiological medical
practitioner for medical exposure.

III.2. ADDITIONAL DATA, RADIOGRAPHY
Table 39 provides a set of paediatric DRLs for Austria, based on a recent
nationwide survey [158].
Table 40, from Borisova et al., provides information on ESD values
obtained for a standard ‘5 year old patient’ in Bulgaria [70]. The ESD values arecalculated from KAP and are compared with the 1996 EC reference values.
Additional useful data, particularly for chest and abdominal ESD and KAP
values, in a number of European centres, are also available in Smans et al. [71].

90TABLE 39. AUSTRIAN DIAGNOSTIC REFERENCE LEVELS FORCOMMON X RAY EXAMINATIONS [158]
Examination

Age (a)Incident air kerma(μGy)

Kerma area product(μGy · m2)

Chest AP/PA

0

50

1.7

Skull AP/PA

Skull lateral

Abdomen AP/PA

1

60

2.3

5

70

2.6

10

90

3.7

15

110

7.3

0

350

15

1

600

25

5

750

35

10

900

45

15

1000

50

0

300

10

1

400

20

5

500

25

10

550

30

15

600

35

0

200

6

1

300

9

5

400

20

10

750

50

15

1000

70

Note: AP: antero-posterior; PA: postero-anterior.

III.3. AN APPROACH TO DIAGNOSTIC REFERENCE LEVELSALLOWING FOR PATIENT THICKNESSThe following data from a Finnish study relate to uncertainty estimations,and the achievable accuracy of ESD and KAP determinations, which is close to20%, in thoracic examinations in Finland (Fig. 1) [159]. This may be consideredwhen comparing patient doses at a hospital with DRLs. Mean KAP and ESD
ranged from 5 to 39 mGy ⋅ cm2 and from 34 to 66 µGy in antero-posterior orpostero-anterior, and from 8 to 109 mGy ⋅ cm2 and 52 to 226 µGy in lateralprojection, depending on patient thickness.

91

FIG. 1. Calculated third quartile values for entrance surface dose (ESD; solid circles) anddose–area product (DAP; open circles, i.e. kerma area product) in chest examinations as afunction of patient thickness in: (a) antero-posterior or postero-anterior projections; (b) lateralprojections (based on Ref. [159]).

TABLE 40. MEAN ENTRANCE SURFACE DOSE (obtained from kerma area
product measurements compared to European diagnostic reference levels in a
5 year old patient [70])Examination

Sample size

Entrance surface
dose (μGy)

Diagnostic reference
level (μGy)

Chest AP/PA

12

86

100

Micturating
cystourethrogram

12

132

—

Intravenous urogram

6

608

900

Pelvis

3

996

1000

Skull

12

86

100

Note: AP: antero-posterior; PA: postero-anterior.

92

The method established by the National Radiological Protection Board(NRPB) of the United Kingdom for setting paediatric DRLs was not consideredfeasible in Finnish practice because of its complexity and the extra uncertainty
introduced by the inexact match between conditions in Finland and those thatprevailed for the NRPB [159, 160]. As exponential curve fitting for KAP and
ESD values correlated well with patient thicknesses, a graphical method seems tobe ideal for setting the DRLs when a sufficient number of patient dose
measurements are not easily available. The Finnish Radiation and Nuclear Safety
Authority has specified paediatric reference levels for thorax imaging in Finland
by using exponential curves that are a function of patient thickness.

93Appendix IV
DISTRIBUTION OF SCATTERED RADIATION IN ROOMS DESIGNEDFOR SPECIAL AND INTERVENTIONAL PROCEDURES

Staff members have to position themselves strategically with respect to theconfiguration of the image receptor–X ray source assembly (Fig. 2). The operator
generally needs to be on the image receptor side and, where possible, needs tostep back during injections. The dominant direction for scatter tends to be fromthe patient backwards towards the X ray tube. This is well illustrated in theisodose diagrams in Fig. 2 [111].
It is important that operators become familiar with the profile of scatteredradiation in the room with the tube oriented in the main directions used inpractice. It is also worth being aware that if equipment has been designed andsold for interventional use that the suppliers, in compliance with international
technical standards, have to provide isodose curves to the end user [50]. While
Balter’s data [111] are based on adults, they provide some guidance for paediatricintervention, pending the availability of more complete paediatric data.

FIG. 2. Typical scatter isodose curves for fluoroscopy systems for different projections [111].
LAO: left anterior oblique; RAO: right anterior oblique.

94

Appendix V
TECHNICAL FACTORS AND DOSE INCOMPUTED TOMOGRAPHY EXAMINATIONS

V.1. TECHNICAL APPROACHES TO DOSE REDUCTION
The following technical aspects of CT scanners are germane to dose reduction
and the establishment of technical protocols for imaging. Support and help in thisregard are available in the literature, from relevant web sites and from suppliers’
representatives. Every effort has to be made to ‘child-size’ protocols [9, 10].
V.1.1. Tube output
In practice, dose reduction can be implemented by reducing the product oftube current and time (mAs). With all other factors held constant, patient dose isdirectly proportional to X ray tube current. For example, a 50% reduction in tube
current results in a 50% decrease in radiation dose. However, the relationshipbetween tube output and noise is more complicated. For example, a fourfold
increase in output (and dose) improves the contrast or signal to noise ratio by afactor of up to two.
Many authors have demonstrated that the same photon flux at the detector canbe achieved with children and adults while greatly reducing the mAs values withthe children. At 120 kVp, Huda et al. reduced the current from 1300 mAs for a bodyweight of 120 kg to 200 mAs for 70 kg and 17 mAs for 10 kg [161]. Boone et al.
reached a constant contrast to noise ratio for abdominal protocols when they
decreased the current from 100% for a 28 cm thick adult phantom, to 56% for a
25 cm phantom, to 20% for a 20 cm phantom and to 5% for a 15 cm phantom [162].
Relatively low tube currents have been recommended for CT of the chest.
Lucaya et al. were able to achieve high resolution CT with reduced dose
(70–80%) and good quality lung images with 34 mAs in cooperative and 50 mAs
in non-cooperative paediatric and young adult patients [163]. Rogalla et al.
recommended a range of tube currents from 25 to 75 mA for a 1 s rotation time
for spiral CT, depending on the age of the patient [162].
A strategy recommended by several authors is to decrease baseline mA
according to body diameter or body composition, and use the shortest rotation
time available [9, 164–167]. This may be achieved by developing and using
exposure charts of tube current settings based on patient weight or diameter at theanatomical regions of interest. Such charts allow the consideration of
optimization of scan parameters in the axial plane.

95Modern multidetector CT scanners generally have the facility for automatictube current modulation, a form of AEC. Data for paediatric scanning haveshown dose reductions of as much as 60% without any clinically significant lossof image quality with such systems [163–171].
Finally, it is important to be aware that one of the risks of low dose scanningin addition to the possibility of missing an important abnormality is a false
positive finding that would not have occurred with a higher tube current and alower noise level.
V.1.2. X ray tube voltage and filtration
The kVp needed to penetrate the body of a child is lower than that needed
for an adult. In adult CT, 120 kVp is used, whereas 100 kVp and sometimes
80 kVp is adequate for children. Lowering the kVp will shift the physicalinteraction of ionizing radiation from Compton scatter towards the total
absorption of the photoelectric effect, thereby enhancing contrast. This improves
the low contrast that otherwise prevails in paediatric radiology owing to the lackof visceral fat [9, 73].
Lower kVp will also improve the contrast available from iodinated agentsand can, thereby, enhance image quality. Excessive lowering of the kVp may
cause artefacts [164] and, in practice, the use of 80 kVp is suggested for infants
under 5 kg. This can sometimes be counterproductive and lead to excessive
artefacts in these small infants when the chest or abdomen is being examined andthe infant is breastfeeding [134]. A lower kVp may also, in some circumstances,
decrease effective dose.
V.1.3. Slice thickness, scan length and pitch
Scan parameters need to be optimized for volume coverage by using
representative volume sample(s) when the entire volume is not needed (bysequential scans with gaps). The maximal slice thickness appropriate for the
specific diagnosis needs to be used. The table increment (axial scanning) or pitch(helical scanning) needs to be increased; where pitch is increased, the amount ofradiation needed to cover the area of interest is decreased.
Thicker collimation with overlapping reconstruction needs to be used whenthin slices are not needed. Additional, thick noise-reduced slices need to bereconstructed without an increase in exposure. Z axis dose modulation and/or
noise-defined AEC will further contribute to dose reduction as they are more
widely deployed. However, some newer scanners may automatically suggest or
give effect to mA increases when the pitch is increased, and this could
compromise potential dose reductions.

96

The minimum length required needs to be scanned, and one needs to be
restrictive in defining upper and lower limits. Localizing projection scans
extending just minimally beyond scan limits need to be used. Major overlap when
scanning adjacent areas with different protocols needs to be avoided. In the caseof multiphase scanning, a shorter scan length needs to be used for additionalscans. The length of scans and fluoroscopy time in interventional applications
need to be minimized. The minimum number of additional sequential functionalscans needs to be used. Test bolus and/or bolus triggering needs to be replaced bya standard scan delay unless timing is very critical.
While the small dimension of a child requires thin slices to improvegeometric resolution, using identical exposure with thinner slices willautomatically increase noise. Keeping the noise level constant requires a morethan proportional increase in the mAs and, thus, radiation exposure. Scanners
with four detector rows are less dose efficient than single row detectors and needinappropriately high dose levels for thin slices. With 8–64 detector rows (andhigher numbers), this phenomenon is less important [9].
V.1.4. Computed tomography detector technology
With single detector CT equipment, the radiation dose is approximately
equal to the conventional contiguous transverse CT. Multidetector CT scanners
use a slip-ring gantry, allowing spiral acquisition at rotation speeds as fast as
0.33 s for a full 360º rotation. The primary advantage of these scanners is theability to scan more than one slice simultaneously and, hence, more efficient useof the radiation delivered from the X ray tube. The number of slices or datachannels acquired per axial rotation continues to increase. Initial reports after the
introduction of multidetector CT indicated increased doses to patients relative tosingle detector CT; more recent reports show comparable or decreased patient
doses [171].
If the user selects settings identical to those used in single detector CT, there
can be an increase in patient dose. Settings have to be determined appropriate to
the specific scanner model. However, the issue is more complicated than thenumber of detector rows, as there have been other associated changes intechnology such as improved detector efficiency, changes in the distance between
the X ray tube and the isocentre, and image reconstruction technology which
includes new filters, and these vary with the different equipment manufacturers.
As with earlier stages of CT technology, there is potential for dose reduction but
the actual dose reduction depends upon how the system is used.
It is important that the radiologist, medical physicists and CT system
operators understand the relationship between dose to patients and image quality
and be aware that often image quality in CT is greater than that needed for97

diagnostic confidence. Objective measures such as image noise or contrast to
noise ratio may not completely capture all of the features relevant to clinicalimage quality. Thus, determining ‘optimal’ image quality can be a complex task,
as both quantitative metrics (e.g. noise) and subjective perceptions are involved.
AEC does not imply total freedom from operator selection of scanparameters. While CT systems without AEC require operator selection of mA or
mAs, AEC systems require an understanding of newer concepts such as noise
index, reference mAs and reference images, so that the AEC can operate
effectively. Gaining an understanding of some parameters, such as the standard
deviation of image pixels or a noise index, is not intuitive and entails
opportunities for error.
Scanning parameters need to be based on study indication, patient size andthe body region being scanned so that radiation dose can be adapted based onthese parameters.

V.2. EFFECTIVE DOSE CALCULATION FROM DOSE LENGTH PRODUCT
Various approaches are used to calculate effective dose from DLP. One of
the simplest is to use published conversion factors, which give normalized
effective dose per unit DLP (mSv · mGy–1 · cm–1). An example of such factors
and the values over which they range for CT scans of head, neck, chest andabdomen and/or pelvis are provided in Table 41.
TABLE 41. CONVERSION FACTORS FROM DOSE LENGTH PRODUCTTO EFFECTIVE DOSE (mSv · mGy–1 · cm–1) [138]
Age

Head

Neck

Chest

Abdomenand/or pelvis

Trunk

0

0.011

0.017

0.039

0.049

0.044

1 year old

0.0067

0.012

0.026

0.030

0.028

5 years old

0.0040

0.011

0.018

0.020

0.019

10 years old

0.00320.0079

0.013

0.015

0.014

Adult

0.00210.0059

0.014

0.015

0.015

98

Appendix VI
INSTRUCTIONS FOR THE CARE OF PAEDIATRIC PATIENTSFOLLOWING DIAGNOSTIC NUCLEAR MEDICINE EXAMINATIONS

The following is drawn from instructions for the care of paediatric patients
following diagnostic nuclear medicine examinations issued by the Dublin Hospitals
Group Risk Management Forum, Radiation Safety Standing Committee in March
2008. Minor edits have been made to generalize the approach.

VI.1. GENERAL REQUIREMENTS
Nursing instructions following nuclear medicine examinations (‘theinstructions’) are to be adhered to by all staff caring for patients who haveundergone nuclear medicine examinations.
It is the responsibility of the specialist radiographer in nuclear medicine toensure that the instructions are provided to the nurse manager responsible for thepatient’s care.
The clinical nurse manager is responsible for ensuring that the instructions
are entered into the patient’s chart, and that the instructions follow the patient incase the patient is transferred from his or her care.
In the case of a patient from an external hospital attending for a nuclear
medicine examination, it is the responsibility of the treating hospital to ensurethat the instructions are provided to the individual responsible for the transfer ofthe patient to the external hospital.
It is then the responsibility of that individual to ensure that the instructions
are provided to the clinical nurse manager responsible for the patient’s care on
arrival at the external hospital.
The hospital needs to ensure that there is a clear identifier system, so that all
staff that may come into contact with the patient are notified of the need forfollowing the instructions.
Examples of identifiers: a colour coded wristband, instructions at the headof the patient’s bed, a label at the head of the patient’s bed.
Instructions are to be observed until 09:00 the day after injection.

99

VI.2. VISITORSAll visitors may be asked to minimize close contact with the patient, andwhere possible remain at a distance of greater than 0.5 m (arm’s length).
Pregnant visitors and/or children need to be discouraged, be asked toremain at a distance of greater than 0.5 m (arm’s length) from the patient, andlimit their visit to 30 min.

VI.3. STAFF
Unless the patient is fasting, they need to be encouraged to drink plenty of
fluids, and empty their bladder frequently.
Standard hygiene procedures need to be used when handling urine bags,
bottles, bedpans, nappies and soiled linen.
Linen and/or clothes soiled with urine need to be double bagged in alginate
bags before storage in laundry bins and sending to the laundry.
Disposable nappies need to be placed in double plastic bags and disposed ofthrough the general clinical waste stream.
Taking non-urgent blood samples needs to be postponed. Urgent blood
samples may be taken after the imaging study is completed, and should belabelled as ‘low level radioactive material, no personal hazard from handling’.
Non-urgent investigations and treatments need to be postponed for 6 h
post-injection if they require staff to work in close contact (less than 0.5 m) withthe patient for more than 30 min. In exceptional circumstances, clinical urgency
may dictate otherwise — the medical physicist or clinical specialist needs to becontacted for specific advice (contact details for the relevant staff need to beprovided here).
It is advised, as a precaution only, that pregnant women do not act as carers
and comforters for such patients if the nursing care involves close contact (lessthan 0.5 m, arm’s length) with the patient for more than 30 min.
It is advised, as a precaution only, to discourage children from playing withother children on wards or in dedicated areas.

100

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CONTRIBUTORS TO DRAFTING AND REVIEW
Callahan, M.*

Children’s Hospital Boston, United States of America

Ciraj-Bjelac, O.

Vinča Institute of Nuclear Sciences, Serbia

Donohue, V.

Children’s University Hospital, Ireland

Kaste, S.*

St. Jude Children’s Research Hospital,
United States of America

Malone, J.

International Atomic Energy Agency

McLean, D.

International Atomic Energy Agency

O’Reilly, G.

St. James’s Hospital, Ireland

Rehani, M.

International Atomic Energy Agency

Ringertz, H.

Karolinska Institute, Sweden

Seuri, R.

Helsinki University Hospital, Finland

Consultants Meetings
Vienna, Austria: 20–22 February 2006
Dublin, Ireland: 18–20 May 2007*

Also representing Image Gently, United States of America.

111

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7HOHSKRQH RU )D[(PDLOVDOHVSXEOLFDWLRQV#LDHDRUJ:HEVLWHKWWSZZZLDHDRUJERRNVR EL AT ED PUBL ICAT IONSRADIATION PROTECTION IN NEWER MEDICALIMAGING TECHNIQUES: PET/CT
Safety Reports Series No. 58
STI/PUB/1343 (41 pp.; 2008)
ISBN 978–92–0–106808–8

Price: €28.00

APPLYING RADIATION SAFETY STANDARDS IN DIAGNOSTIC
RADIOLOGY AND INTERVENTIONAL PROCEDURES USING X RAYS
Safety Reports Series No. 39
STI/PUB/1206 (96 pp.; 2006)
ISBN 92–0–111004–9

Price: €28.00

RADIATION PROTECTION IN NEWER MEDICAL IMAGING TECHNIQUES:CARDIAC CT
Safety Reports Series No. 60
STI/PUB/1366 (19 pp.; 2009)ISBN 978–92–0–111208–8

Price: €18.00

ESTABLISHING GUIDANCE LEVELS IN X RAY GUIDED MEDICALINTERVENTIONAL PROCEDURES: A PILOT STUDY
Safety Reports Series No. 59
STI/PUB/1346 (147 pp.; 2009)ISBN 978–92–0–107308–2

Price: €32.00

AVOIDANCE OF UNNECESSARY DOSE TO PATIENTS WHILE
TRANSITIONING FROM ANALOGUE TO DIGITAL RADIOLOGY
IAEA TECDOC Series No. 1667
IAEA-TECDOC-1667 (85 pp.; 2012)
ISBN 978–92–0–121010–4

Price: €18.00

DOSE REDUCTION IN CT WHILE MAINTAINING DIAGNOSTICCONFIDENCE: A FEASIBILITY/DEMONSTRATION STUDY
IAEA TECDOC Series No. 1621
IAEA-TECDOC-1621 (55 pp.; 2009)ISBN 978–92–0–108009–7

Price: €15.00

PATIENT DOSE OPTIMIZATION IN FLUOROSCOPICALLY GUIDEDINTERVENTIONAL PROCEDURES
IAEA TECDOC Series No. 1641
IAEA-TECDOC-1641 (95 pp.; 2010)
ISBN 978–92–0–100510–6

www.iaea.org/books

Price: €15.00

The Fundamental Safety Principles and theI A E A ' s G en er al S af ety Rqu ir e ments publ i cati on,
Radiation Protection and Safety of Radiation
Sources: International Basic Safety Standards(BSS) require the radiological protectionof patients undergoing medical exposurest h r o u g h ju s tif ication of th e p rocedures involved
and through optimization. This publicationp r o vides g u idan ce to r adiolog ists, other cl i ni ci ans
and radiographers/technologists involved indiagnostic procedures using ionizing radiation
wit h ch ildr en an d adoles cen ts. It i s al so ai med
a t m edical ph ys icis ts an d r eg ul ators. The focus i so n t h e m eas u r es n eces s ar y to prov i de protecti on
f ro m t h e ef f ects of r adiation usi ng the pri nci pl es
established in the BSS and according to thep r io r ity g iven to th is is s u e.

INTERNATIONAL ATOMIC ENERGY AGENCY
VIENNA
ISBN 978–92–0–125710–9
ISSN 1020–6450