IEC 62985:2019
(Main)Methods for calculating size specific dose estimates (SSDE) for computed tomography
Methods for calculating size specific dose estimates (SSDE) for computed tomography
IEC 62985:2019 applies to
– CT SCANNERS that are able to display and report CTDIVOL in accordance with
IEC 60601-2-44, and
– RADIATION dose index monitoring software (RDIMS)
for the purpose of calculating, displaying and recording the SIZE SPECIFIC DOSE ESTIMATE (SSDE) and its associated components.
Specifically, this document provides standardized methods and requirements for calculating, displaying, or recording of SSDE, SSDE(z), WATER EQUIVALENT DIAMETER (DW), and DW(z), where z represents a specific longitudinal position of the scanned object.
This document provides a method of determining a reference WATER EQUIVALENT DIAMETER, DW,REF(z), using CT scans of two cylindrical water PHANTOMS and one or more anthropomorphic PHANTOM(S), which conform to the specifications defined in this document. The method of calculating the WATER EQUIVALENT DIAMETER that is implemented by the MANUFACTURER, DW,IMP(z), is tested and validated against DW,REF(z) using the TEST OBJECTS and methods defined within this document. This document also describes the methods for calculating SSDE and DW, which represent the average values of SSDE(z) and DW(z) over the RECONSTRUCTION LENGTH.
The contents of the corrigendum of June 2022 have been included in this copy.
Méthodes de calcul de l’estimateur de dose morphologique (SSDE) en tomodensitométrie
L'IEC 62985:2019 s’applique:
– aux TOMODENSITOMETRES qui sont capables d’afficher et de notifier CTDIVOL conformément à l’IEC 60601-2-44, et
– au logiciel de surveillance de l’indice de dose de RAYONNEMENT (RDIMS - RADIATION Dose Index Monitoring Software)
pour les besoins de calcul, d’affichage et d’enregistrement de l’ESTIMATEUR DE DOSE MORPHOLOGIQUE (SSDE) et de ses composantes associées.
Plus spécifiquement, le présent document fournit des méthodes et des exigences normalisées pour le calcul, l’affichage ou l’enregistrement du SSDE, du SSDE(z), du DIAMETRE EQUIVALENT EAU (DW), et de DW(z), où z représente une position longitudinale spécifique de l’objet balayé.
Le présent document fournit une méthode permettant de déterminer un DIAMETRE EQUIVALENT EAU de référence, DW,REF(z), par balayage TOMOGRAPHIQUE de deux FANTOMES d’eau cylindriques et d’un ou plusieurs FANTOMES anthropomorphiques conformes aux spécifications définies dans le présent document. La méthode de calcul du DIAMETRE EQUIVALENT EAU appliquée par le FABRICANT, DW,IMP(z), est vérifiée par essai et validée par rapport à la valeur DW,REF(z) en utilisant les OBJETS D’ESSAI et les méthodes définis dans le présent document. Le présent document décrit également les méthodes de calcul du SSDE et DW, qui représentent les valeurs moyennes du SSDE(z) et du DW(z) sur l’ensemble de la LONGUEUR DE RECONSTRUCTION.
Le contenu du corrigendum de juin 2022 a été pris en considération dans cet exemplaire.
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IEC 62985 ®
Edition 1.0 2019-09
INTERNATIONAL
STANDARD
Methods for calculating size specific dose estimates (SSDE) for computed
tomography
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form
or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from
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International Standards for all electrical, electronic and related technologies.
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IEC 62985 ®
Edition 1.0 2019-09
INTERNATIONAL
STANDARD
Methods for calculating size specific dose estimates (SSDE) for computed
tomography
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 11.040.50 ISBN 978-2-8322-7290-9
– 2 – IEC 62985:2019 © IEC 2019
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 7
2 Normative references . 7
3 Terms and definitions . 7
4 Verification of method used to calculate D (z) . 9
W
4.1 General . 9
4.2 Characteristics of the water PHANTOMS . 9
4.3 Characteristics of the anthropomorphic PHANTOM . 10
4.4 Generation of D (z) for the water PHANTOMS . 10
W,REF
4.5 Verification of D for the water PHANTOMS . 10
W,REF
4.6 Generation of D for the water PHANTOMS . 10
W,IMP
4.7 Verification of D (z) against D (z) for the water PHANTOMS . 11
W,IMP W,REF
4.8 Generation of D (z) for the anthropomorphic PHANTOM. 11
W,REF
4.9 Generation of D (z) for the anthropomorphic PHANTOM . 12
W,IMP
4.10 Verification of D (z) against D (z) for the anthropomorphic
W,IMP W,REF
PHANTOM . 12
5 Requirements and limitations . 12
5.1 Calculation of SSDE and D for CT SCANNERS and RDIMS . 12
W
5.2 Pre-scan display of SSDE for CT SCANNERs . 12
5.3 Post-scan updating of SSDE and D for CT SCANNERS . 12
W
5.4 Pre and post-scan display of SSDE and D for CT SCANNERS . 13
W
5.5 Post-scan recording of SSDE and D for CT SCANNERS . 13
W
5.6 Limitations of calculation and display of SSDE and D . 13
W
5.7 Requirements for identification of limitations in the ACCOMPANYING
DOCUMENTS . 13
5.8 Updating SSDE conversion factors, ƒ . 14
Annex A (normative) SSDE conversion factors . 15
A.1 Clarification regarding the use of effective diameter versus D . 15
W
A.2 Equation for determination of SSDE conversion factor . 15
Annex B (normative) Language regarding the general limitations of the SSDE
methodology for use in the ACCOMPANYING DOCUMENTS . 17
Annex C (informative) Estimates of the magnitude of uncertainties from special clinical
scenarios . 18
C.1 General . 18
C.2 Neck included in scanned anatomy . 18
C.3 Range of scan projection radiograph exceeded . 18
C.4 Single or bilateral extremities scanned . 18
C.5 PATIENT not positioned at the centre of rotation along the source/detector
direction . 19
C.6 PATIENT anatomy outside the scan field of view . 19
C.7 Foreign objects within the scanned projection radiograph or scan volume . 19
Bibliography . 20
Index of defined terms used in this document . 21
Figure A.1 – Visualization of ƒ(D ) versus D for the body and head parameters
w W
provided in Table A.1 . 16
Table 1 – Anthropomorphic PHANTOM regions to be scanned . 11
Table A.1 – SSDE Conversion factor as a function of D . 15
W
– 4 – IEC 62985:2019 © IEC 2019
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
METHODS FOR CALCULATING SIZE SPECIFIC DOSE
ESTIMATES (SSDE) FOR COMPUTED TOMOGRAPHY
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as "IEC
Publication(s)"). Their preparation is entrusted to technical committees; any IEC National Committee interested
in the subject dealt with may participate in this preparatory work. International, governmental and non-
governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely
with the International Organization for Standardization (ISO) in accordance with conditions determined by
agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 62985 has been prepared by subcommittee 62B: Diagnostic
imaging equipment, of IEC technical committee 62: Electrical equipment in medical practice.
The text of this International Standard is based on the following documents:
FDIS Report on voting
62B/1133/FDIS 62B/1144/RVD
Full information on the voting for the approval of this International Standard can be found in
the report on voting indicated in the above table.
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.
In this document, the following print types are used:
– requirements and definitions: roman type;
– informative material appearing outside of tables, such as notes, examples and references: in smaller type.
Normative text of tables is also in a smaller type;
– TERMS DEFINED IN CLAUSE 3, IN CLAUSE 3 OF IEC 60601-1:2005 AND
IEC 60601-1:2005/AMD1:2012, OF THE COLLATERAL STANDARDS, OF IEC TR 60788:2004 OR
AS NOTED: SMALL CAPITALS.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under "http://webstore.iec.ch" in the data related to
the specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
NOTE The attention of the user of this document is drawn to the fact that equipment MANUFACTURERS and testing
organizations may need a transitional period following publication of a new, amended or revised IEC publication in
which to make products in accordance with the new requirements and to equip themselves for conducting new or
revised tests. It is the recommendation of the committee that the content of this publication be adopted for
implementation nationally not earlier than 3 years from the date of publication.
The contents of the corrigendum 1 (2022-06) have been included in this copy.
– 6 – IEC 62985:2019 © IEC 2019
INTRODUCTION
The SIZE SPECIFIC DOSE ESTIMATE (SSDE) is an estimate of the average ABSORBED DOSE to the
scan volume that takes into account the ATTENUATION of the anatomy being scanned (using
the WATER EQUIVALENT DIAMETER D ) and the RADIATION OUTPUT of the CT SCANNER (using
W
CTDI ).
VOL
SSDE is intended to provide a dose estimate for PATIENTs of all sizes. SSDE, which is given in
units of mGy, is especially important for small paediatric PATIENTS since the corresponding
applied level of RADIATION (CTDI , also given in units of mGy) does not adequately indicate
VOL
the absorbed RADIATION DOSE.
SSDE is calculated using a SSDE CONVERSION FACTOR AT LONGITUDINAL POSITION Z (ƒ) and the
...
IEC 62985 ®
Edition 1.0 2019-09
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Methods for calculating size specific dose estimates (SSDE) for computed
tomography
Méthodes de calcul de l’estimateur de dose morphologique (SSDE) en
tomodensitométrie
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form
or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from
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copyright or have an enquiry about obtaining additional rights to this publication, please contact the address below or
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CH-1211 Geneva 20 www.iec.ch
Switzerland
About the IEC
The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes
International Standards for all electrical, electronic and related technologies.
About IEC publications
The technical content of IEC publications is kept under constant review by the IEC. Please make sure that you have the
latest edition, a corrigendum or an amendment might have been published.
IEC publications search - webstore.iec.ch/advsearchform Electropedia - www.electropedia.org
The advanced search enables to find IEC publications by a The world's leading online dictionary on electrotechnology,
variety of criteria (reference number, text, technical containing more than 22 000 terminological entries in English
committee,…). It also gives information on projects, replaced and French, with equivalent terms in 16 additional languages.
and withdrawn publications. Also known as the International Electrotechnical Vocabulary
(IEV) online.
IEC Just Published - webstore.iec.ch/justpublished
Stay up to date on all new IEC publications. Just Published IEC Glossary - std.iec.ch/glossary
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once a month by email. French extracted from the Terms and Definitions clause of
IEC publications issued since 2002. Some entries have been
IEC Customer Service Centre - webstore.iec.ch/csc collected from earlier publications of IEC TC 37, 77, 86 and
If you wish to give us your feedback on this publication or CISPR.
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IEC 62985 ®
Edition 1.0 2019-09
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Methods for calculating size specific dose estimates (SSDE) for computed
tomography
Méthodes de calcul de l’estimateur de dose morphologique (SSDE) en
tomodensitométrie
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 11.040.50 ISBN 978-2-8322-7950-2
– 2 – IEC 62985:2019 © IEC 2019
CONTENTS
CONTENTS . 2
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 7
2 Normative references . 7
3 Terms and definitions . 8
4 Verification of method used to calculate D (z) . 9
W
4.1 General . 9
4.2 Characteristics of the water PHANTOMS . 10
4.3 Characteristics of the anthropomorphic PHANTOM . 10
4.4 Generation of D (z) for the water PHANTOMS . 10
W,REF
4.5 Verification of D for the water PHANTOMS . 11
W,REF
4.6 Generation of D for the water PHANTOMS . 11
W,IMP
4.7 Verification of D (z) against D (z) for the water PHANTOMS . 11
W,IMP W,REF
4.8 Generation of D (z) for the anthropomorphic PHANTOM. 11
W,REF
4.9 Generation of D (z) for the anthropomorphic PHANTOM . 12
W,IMP
4.10 Verification of D (z) against D (z) for the anthropomorphic
W,IMP W,REF
PHANTOM . 12
5 Requirements and limitations . 12
5.1 Calculation of SSDE and D for CT SCANNERS and RDIMS . 12
W
5.2 Pre-scan display of SSDE for CT SCANNERs . 12
5.3 Post-scan updating of SSDE and D for CT SCANNERS . 12
W
5.4 Pre and post-scan display of SSDE and D for CT SCANNERS . 13
W
5.5 Post-scan recording of SSDE and D for CT SCANNERS . 13
W
5.6 Limitations of calculation and display of SSDE and D . 13
W
5.7 Requirements for identification of limitations in the ACCOMPANYING
DOCUMENTS . 14
5.8 Updating SSDE conversion factors, ƒ . 14
Annex A (normative) SSDE conversion factors . 15
A.1 Clarification regarding the use of effective diameter versus D . 15
W
A.2 Equation for determination of SSDE conversion factor . 15
Annex B (normative) Language regarding the general limitations of the SSDE
methodology for use in the ACCOMPANYING DOCUMENTS . 17
Annex C (informative) Estimates of the magnitude of uncertainties from special clinical
scenarios . 18
C.1 General . 18
C.2 Neck included in scanned anatomy . 18
C.3 Range of scan projection radiograph exceeded . 18
C.4 Single or bilateral extremities scanned . 18
C.5 PATIENT not positioned at the centre of rotation along the source/detector
direction . 19
C.6 PATIENT anatomy outside the scan field of view . 19
C.7 Foreign objects within the scanned projection radiograph or scan volume . 19
Bibliography . 20
Index of defined terms used in this document . 21
Figure A.1 – Visualization of ƒ(D ) versus D for the body and head parameters
w W
provided in Table A.1 . 16
Table 1 – Anthropomorphic PHANTOM regions to be scanned . 11
Table A.1 – SSDE Conversion factor as a function of D . 15
W
– 4 – IEC 62985:2019 © IEC 2019
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
METHODS FOR CALCULATING SIZE SPECIFIC DOSE
ESTIMATES (SSDE) FOR COMPUTED TOMOGRAPHY
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as "IEC
Publication(s)"). Their preparation is entrusted to technical committees; any IEC National Committee interested
in the subject dealt with may participate in this preparatory work. International, governmental and non-
governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely
with the International Organization for Standardization (ISO) in accordance with conditions determined by
agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that
...
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