SIST EN IEC 60601-2-33:2024

SLOVENSKI STANDARD
01-november-2024
Medicinska električna oprema - 2-33. del: Posebne zahteve za osnovno varnost in
bistvene lastnosti opreme za magnetno resonanco za medicinsko diagnostiko (IEC
60601-2-33:2022)
Medical electrical equipment - Part 2-33: Particular requirements for the basic safety and
essential performance of magnetic resonance equipment for medical diagnosis (IEC
60601-2-33:2022)
Medizinische elektrische Geräte - Teil 2-33: Besondere Festlegungen für die Sicherheit
von Magnetresonanzgeräten für die medizinische Diagnostik (IEC 60601-2-33:2022)
Appareils électromédicaux - Partie 2-33: Exigences particulières pour la sécurité de base
et les performances essentielles des appareils à résonance magnétique utilisés pour le
diagnostic médical (IEC 60601-2-33:2022)
Ta slovenski standard je istoveten z: EN IEC 60601-2-33:2024
ICS:
11.040.55 Diagnostična oprema Diagnostic equipment
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD EN IEC 60601-2-33

NORME EUROPÉENNE
EUROPÄISCHE NORM September 2024
ICS 11.040.55 Supersedes EN 60601-2-33:2010/corrigendum Oct. 2010;
EN 60601-2-33:2010; EN 60601-2-33:2010/A11:2011; EN
60601-2-33:2010/A1:2015; EN 60601-2-33:2010/A2:2015;
EN 60601-2-33:2010/A12:2016; EN 60601-2-
33:2010/AC:2016-03
English Version
Medical electrical equipment - Part 2-33: Particular requirements
for the basic safety and essential performance of magnetic
resonance equipment for medical diagnosis
(IEC 60601-2-33:2022)
Appareils électromédicaux - Partie 2-33: Exigences Medizinische elektrische Geräte - Teil 2-33: Besondere
particulières pour la sécurité de base et les performances Festlegungen für die Sicherheit von
essentielles des appareils à résonance magnétique utilisés Magnetresonanzgeräten für die medizinische Diagnostik
pour le diagnostic médical (IEC 60601-2-33:2022)
(IEC 60601-2-33:2022)
This European Standard was approved by CENELEC on 2022-09-08. CENELEC members are bound to comply with the CEN/CENELEC
Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.
Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC
Management Centre or to any CENELEC member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CENELEC member into its own language and notified to the CEN-CENELEC Management Centre has the
same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic,
Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the
Netherlands, Norway, Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Türkiye and the United Kingdom.

European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2024 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN IEC 60601-2-33:2024 E

European foreword
The text of document 62B/1277/FDIS, future edition 4 of IEC 60601-2-33, prepared by SC 62B
"Medical imaging equipment, software, and systems" of IEC/TC 62 "Medical equipment, software, and
systems" was submitted to the IEC-CENELEC parallel vote and approved by CENELEC as
The following dates are fixed:
• latest date by which the document has to be implemented at national (dop) 2025-03-20
level by publication of an identical national standard or by endorsement
• latest date by which the national standards conflicting with the (dow) 2027-09-20
document have to be withdrawn
This document supersedes EN 60601-2-33:2010 and all of its amendments and corrigenda (if any).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CENELEC shall not be held responsible for identifying any or all such patent rights.
Any feedback and questions on this document should be directed to the users’ national committee. A
complete listing of these bodies can be found on the CENELEC website.
Endorsement notice
The text of the International Standard IEC 60601-2-33:2022 was approved by CENELEC as a
European Standard without any modification.
In the official version, for Bibliography, the following notes have to be added for the standard indicated:
IEC 60601-1-3 NOTE Approved as EN 60601-1-3
IEC 60601-1-9 NOTE Approved as EN 60601-1-9
IEC 60601-1-10 NOTE Approved as EN 60601-1-10
IEC 60601-1-11 NOTE Approved as EN 60601-1-11
IEC 60601-1-12 NOTE Approved as EN 60601-1-12
IEC 62464-1 NOTE Approved as EN IEC 62464-1
IEC 60364-7-710 NOTE Approved as HD 60364-7-710
IEC 60601-2-62:2013 NOTE Approved as EN 60601-2-62:2015 (not modified)
ISO 14630:2012 NOTE Approved as EN ISO 14630:2012 (not modified)
ISO 14971:2019 NOTE Approved as EN ISO 14971:2019 (not modified) +A11:2021
IEC 62366-1:2015 NOTE Approved as EN 62366-1:2015 (not modified)
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments)
applies.
NOTE 1  Where an International Publication has been modified by common modifications, indicated by (mod),
the relevant EN/HD applies.
NOTE 2  Up-to-date information on the latest versions of the European Standards listed in this annex is available
here: www.cencenelec.eu.
Annex ZA of EN 60601-1:2006 , applies, except as follows:
Replace:
Publication Year Title EN/HD Year
IEC 60601-1-2 2014 Medical electrical equipment - Part 1-2: EN 60601-1-2 2015
General requirements for basic safety and
essential performance - Collateral
Standard: Electromagnetic disturbances -
Requirements and tests
+ A1 2020 + A1 2021
Add:
Publication Year Title EN/HD Year
IEC 60601-1 2005 Medical electrical equipment - Part 1: EN 60601-1 2006
General requirements for basic safety and
essential performance
- - + AC 2010
+ A1 2012 + A1 2013
- - + AC 2014
- - + A12 2014
+ A2 2020 + A2 2021
- - + AC 2022
- - + A13 2024
IEC 60695-11-10 2013 Fire hazard testing - Part 11-10: Test EN 60695-11-10 2013
flames - 50 W horizontal and vertical flame
test methods
As impacted by EN 60601-1:2006/AC:2010, EN 60601-1:2006/A1:2013, EN 60601-1:2006/A1:2013/AC:2014,
EN 60601-1:2006/A12:2014, EN 60601-1:2006/A2:2021, EN 60601-1:2006/AC:2022-12 and
EN 60601-1:2006/A13:2024.
Publication Year Title EN/HD Year
IEC 61672-1 2013 Electroacoustics - Sound level meters - EN 61672-1 2013
Part 1: Specifications
IEC 61672-2 2013 Electroacoustics - Sound level meters - EN 61672-2 2013
Part 2: Pattern evaluation tests
IEC 62570 2014 Standard practice for marking medical EN 62570 2015
devices and other items for safety in the
magnetic resonance environment
ISO 3746 2010 Acoustics - Determination of sound power EN ISO 3746 2010
levels and sound energy levels of noise
sources using sound pressure - Survey
method using an enveloping measurement
surface over a reflecting plane
ISO 9614-1 - Acoustics - Determination of sound power EN ISO 9614-1 -
levels of noise sources using sound
intensity - Part 1: Measurement at discrete
points
NEMA MS 4 - Acoustic noise measurement procedure for - -
diagnostic Magnetic Resonance Imaging
(MRI) devices
NEMA MS 8 - Characterization of the specific absorption - -
rate (SAR) for magnetic resonance
imaging systems
NEMA MS 14 - Characterization of radiofrequency (RF) - -
coil heating in magnetic resonance imaging
systems
IEC 60601-2-33 ®
Edition 4.0 2022-08
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Medical electrical equipment –

Part 2-33: Particular requirements for the basic safety and essential performance

of magnetic resonance equipment for medical diagnosis

Appareils électromédicaux –
Partie 2-33: Exigences particulières pour la sécurité de base et les performances

essentielles des appareils à résonance magnétique utilisés pour le diagnostic

médical
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 11.040.55 ISBN 978-2-8322-3955-1

IEC 60601-2-33:2022/ISH1:2023 – 1 –
© IEC 2023
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
IEC 60601-2-33
Edition 4.0  2022-08
MEDICAL ELECTRICAL EQUIPMENT –

Part 2-33: Particular requirements for the basic safety and essential
performance of magnetic resonance equipment for medical diagnosis

INTERPRETATION SHEET 1
This interpretation sheet has been prepared by subcommittee 62B: Medical imaging equipment,
software, and systems, of IEC technical committee 62: Medical equipment, software, and
systems.
The text of this interpretation sheet is based on the following documents:
DISH Report on voting
62B/1315/DISH 62B/1319/RVDISH
Full information on the voting for the approval of this interpretation sheet can be found in the
report on voting indicated in the above table.

___________
Definition 201.3.214 (EFFECTIVE STIMULUS DURATION t )
s,eff
The definition is clarified by the following:
a) It is important to consider that the magnetic field gradient displayed in Figure 201.101 can
GRADIENT UNITS.
be realized by simultaneous activation of multiple
b) The concept of t applies both to cardiac stimulation and peripheral nerve stimulation.
s,eff
c) The appropriate timescale for evaluating the duration of monotonic increase or decrease of
the GRADIENT OUTPUT is in the order of the chronaxie. When a discrete time-segment based
approach is used for numerical evaluation, one or more discrete time segments deviating
from monotonic increase or decrease will likely not reset t nor modify the likelihood of
s,eff
stimulation. Application of a filter as suggested in Annex AA (Formula AA.22) can prevent
unintentional misinterpretation of monotonicity.
ICS 11.040.55
IEC 60601-2-33:2022-08/ISH1:2023-05(en)

– 2 – IEC 60601-2-33:2022/ISH1:2023
© IEC 2023
Definition 201.3.219 (HEAD SAR)
Note 1 to entry is clarified as follows:
Extent of the head as provided in the note to entry represents a common understanding of
medical professionals. Variation in assessment volume for HEAD SAR is acceptable for use by
the MR MANUFACTURER when implementing IEC 60601-2-33. For example, these volumes could
be (tilted) axial demarcations of cervical vertebrae C3, C5, or C7.

– 2 – IEC 60601-2-33:2022 © IEC 2022
CONTENTS
FOREWORD . 4
* INTRODUCTION . 7
201.1 Scope, object and related standards . 8
201.2 Normative references . 9
201.3 Terms and definitions . 10
201.4 General requirements . 18
201.5 General requirements for testing of ME EQUIPMENT . 18
201.6 Classification of ME EQUIPMENT and ME SYSTEMS . 18
201.7 ME EQUIPMENT identification, marking and documents . 19
201.8 Protection against electrical HAZARDS from ME EQUIPMENT . 36
201.9 Protection against MECHANICAL HAZARDs of ME EQUIPMENT and ME SYSTEMS . 37
201.10 Protection against unwanted and excessive radiation HAZARDS . 39
201.11 Protection against excessive temperatures and other HAZARDS . 39
201.12 Accuracy of controls and instruments and protection against hazardous
outputs . 39
201.13 HAZARDOUS SITUATIONS and fault conditions for ME EQUIPMENT . 60
201.14 PROGRAMMABLE ELECTRICAL MEDICAL SYSTEM (PEMS) . 61
201.15 Construction of ME EQUIPMENT . 61
201.16 ME SYSTEMS . 61
201.17 ELECTROMAGNETIC COMPATIBILITY of ME EQUIPMENT and ME SYSTEMS . 62
202 ELECTROMAGNETIC DISTURBANCES – Requirements and tests . 62
Annexes . 65
Annex A (informative) Symbols on marking . 66
Annex AA (informative) Particular guidance and rationale . 70
Bibliography . 130
Index of defined terms used in this document . 142

Figure 201.101 – Gradient waveform and EFFECTIVE STIMULUS DURATION . 13
Figure 201.102 – Limits for cardiac and peripheral nerve stimulation . 44
Figure 201.103 – Applicable WHOLE BODY SAR limit values in FIRST LEVEL CONTROLLED
OPERATING MODE as function of AMBIENT TEMPERATURE . 47
Figure 201.104 – Volume for determining the spatial maximum of GRADIENT OUTPUT . 54
Figure 201.105 – Volume for determining the B stray field. 56
Figure AA.1 – SAR limits for the exposed mass of a PATIENT . 76
Figure AA.2 – Static magnetic fields: flow potentials and retardation . 93
Figure AA.3 – Bulls eye view for SFG at multiple equidistant cylinders . 105
Figure AA.4 – Experimental data on PNS THRESHOLD LEVEL of human volunteers in
WHOLE BODY GRADIENT SYSTEM . 114
Figure AA.5 – Double logarithmic plot of experimental threshold values for peripheral
nerve stimulation . 115
Figure AA.6 – Response value R(t) generated by convolution of a rectangular
stimulus dB/dt and a nerve impulse response function n(t-θ) . 120

IEC 60601-2-33:2022 © IEC 2022 – 3 –
Figure AA.7 – Gradient waveform G, stimulus waveform dB/dt and response value R,
for a trapezoid EPI waveform starting at t = 0 . 120
Figure AA.8 – Threshold values dB/dt for two gradient waveforms, plotted against
EFFECTIVE STIMULUS DURATION . 121
Figure AA.9 – Threshold value of dB/dt for a sinusoid gradient waveform, as function of
the number of half periods in the waveform . 121
Figure AA.10 – Schematic overview of various possible hardware configurations of a
birdcage coil and their appropriate classification . 126

Table 201.101 – Units outside the SI units system that may be used on MR EQUIPMENT . 20
Table 201.102 – Rheobase values per type of gradient system . 43
Table 201.103 – Weighting factors for PNS evaluation per GRADIENT UNIT . 45
Table 201.104 – SAR limits for VOLUME RF TRANSMIT COILS . 46
Table 201.105 – SAR limits for LOCAL RF TRANSMIT COILs . 46
+
Table 201.106 – Maximum B PEAK values for MROC implementation . 58
Table 201.107 – User selectable control parameters for MROC implementation . 59
Table 201.A.101 – MR SAFETY SIGNs . 66
Table 201.A.102 – RF coil symbols . 68
Table 201.A.103 – MR CONDITIONAL symbols . 69
Table 201.AA.101 – Overview of quantities, and their SI units . 80
Table 201.AA.102 – Overview physiological effects in humans, animals and model
systems, for magnetic-field exposures at field strengths relevant for MRI . 83
Table 201.AA.103 – CORE TEMPERATURE limits . 122

– 4 – IEC 60601-2-33:2022 © IEC 2022
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
MEDICAL ELECTRICAL EQUIPMENT –

Part 2-33: Particular requirements for the basic safety and essential
performance of magnetic resonance equipment for medical diagnosis

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 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.
IEC 60601-2-33 has been prepared by subcommittee 62B: Diagnostic imaging equipment, of
IEC technical committee 62: Electrical equipment in medical practice. It is an International
Standard.
This fourth edition cancels and replaces the third edition published in 2010, Amendment 1:2013
and Amendment 2:2015. This edition constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) aligned with IEC 60601-1:2005 and its two amendments IEC 60601-1:2005/AMD1:2012 and
IEC 60601-1:2005/AMD2:2020;
b) addition of safety requirements for the EMERGENCY FIELD SHUT DOWN UNIT;
c) clarification of acoustic protection measures for the PATIENT and MR WORKER;
d) addition of noise emission declaration for exposure inside the MR EXAMINATION ROOM, to
support occupational health assessment by the RESPONSIBLE ORGANIZATION;

IEC 60601-2-33:2022 © IEC 2022 – 5 –
e) addition of compliance methods for thermal safety of RF coils;
f) addition of RF transmit definitions to match MR CONDITIONAL labelling requirements for
MEDICAL DEVICES;
g) clarification of requirements for MR CONDITIONAL labelling of ACCESSORIES;
h) alignment of static magnetic field limit for B HAZARD area to limits in other MEDICAL DEVICE
standards (especially that for pacemakers, ISO 14117), the new limit value being 0,9 mT;
i) improved description of the magnetic field related plots in the Compatibility Technical
Specification Sheet (CTSS);
j) provision of compatibility sequences (in the CTSS) to test auxiliary equipment by the MR
manufacturer has become optional, and is expected to be eliminated in a future edition;
k) a separate section with requirements for a site-planning document containing safety
information;
l) requirements for the alerting function (PATIENT to OPERATOR);
m) introduction of MROC as mandatory functionality for 1,5 T and 3 T systems to facilitate
scanning of PATIENTs with MEDICAL DEVICES labelled as MR CONDITIONAL, unless such
scanning is explicitly contra-indicated by the MR MANUFACTURER;
n) RF coil symbols in Table 201.A.102 have become mandatory, and the preferred and
alternate signs have been swapped relative to the previous edition, with preferred now being
the sign with color;
o) determination of the B stray field in 201.12.4.105.3.3 based on calculations only.
The text of this International Standard is based on the following documents:
Draft Report on voting
62B/1277/FDIS 62B/1284/RVD
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this International Standard is English.
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at http://www.iec.ch/members_experts/refdocs. The main document types developed by IEC
are described in greater detail at www.iec.ch/standardsdev/publications.
In this document, the following print types are used:
– requirements and definitions: roman type;
– test specifications: italic 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 OF IEC 60601-1:2005, IEC 60601-1:2005/AMD1:2012 AND
IEC 60601-1:2005/AMD2:2020, IN THIS DOCUMENT OR AS NOTED: SMALL CAPITALS.
In referring to the structure of this document, the term
– "clause" means one of the eighteen numbered divisions within the table of contents,
inclusive of all subdivisions (e.g. Clause 7 includes subclauses 7.1, 7.2, etc.);
– "subclause" means a numbered subdivision of a clause (e.g. 7.1, 7.2 and 7.2.1 are all
subclauses of Clause 7).
References to clauses within this document are preceded by the term "Clause" followed by the
clause number. References to subclauses within this document are by number only.

– 6 – IEC 60601-2-33:2022 © IEC 2022
In this document, the conjunctive "or" is used as an "inclusive or" so a statement is true if any
combination of the conditions is true.
The verbal forms used in this document conform to usage described in Clause 7 of the ISO/IEC
Directives, Part 2. For the purposes of this document, the auxiliary verb:
– "shall" means that compliance with a requirement or a test is mandatory for compliance with
this document;
– "should" means that compliance with a requirement or a test is recommended but is not
mandatory for compliance with this document;
– "may" is used to describe a permissible way to achieve compliance with a requirement or
test.
An asterisk (*) as the first character of a title or at the beginning of a paragraph or table title
indicates that there is guidance or rationale related to that item in Annex AA.
A list of all parts of the IEC 60601 and IEC 80601 series, published under the general title:
Medical electrical equipment, can be found on the IEC website.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under webstore.iec.ch/?ref=menu in the data related
to the specific document. At this date, the document will be
 reconfirmed,
 withdrawn,
 replaced by a revised edition, or
 amended.
The contents of the Interpretation Sheet 1 of May 2023 have been included in this copy.
IMPORTANT – The "colour inside" logo on the cover page of this document indicates that it
contains colours which are considered to be useful for the correct understanding of its
contents. Users should therefore print this document using a colour printer.

IEC 60601-2-33:2022 © IEC 2022 – 7 –
* INTRODUCTION
This International Standard addresses technical aspects of medical diagnostic MR EQUIPMENT
and MR SYSTEMS, necessary to ensure the safety of PATIENTs, and to address electromagnetic
field (EMF) exposure concerns for MR WORKERs involved with the operation, development,
manufacturing, installation, and servicing of MR EQUIPMENT and MR SYSTEMS. Annex AA provides
rationales for requirements and limit values including references to peer-reviewed publications
used to establish the content of this document.
Exposure limits for PATIENTs and for MR WORKERs are selected to protect them from transient
adverse health effects and from unacceptable RISK. In addition, scientific consensus today is
that no experimental or theoretical basis exists to expect long-term adverse health effects in
humans from (repeated) EMF exposures.
Organizational aspects related to safety of operating the MR EQUIPMENT are the task of the
RESPONSIBLE ORGANIZATION. This task includes, but is not limited to:
– qualification of staff for decisions that are related to safety;
– adequate training of staff;
– definition of medical responsibility; including
• rules for screening the PATIENT for contraindications or for conditions that can affect
acceptable exposure;
• rules for ROUTINE MONITORING, and for MEDICAL SUPERVISION of the PATIENT during the MR
EXAMINATION;
• rules for access to and oversight of the MR ENVIRONMENT, and for hearing protection;
– demarcating, maintaining and controlling access to the B HAZARD AREA and the MR
ENVIRONMENT, including
• screening of any person entering this environment;
• confirming that no materials or equipment entering this environment pose a HAZARD.
– emergency procedures for (rapid) removal of the PATIENT who is in the B HAZARD AREA;
– emergency procedures related to a potential QUENCH of a superconductive magnet, when
applicable;
– rules to minimize and to limit the exposure of MR workers to EMF;
– establishing and ensuring adequate preventive maintenance;
– evaluation and implementation of local regulations.
This fourth edition aligns with IEC 60601-1:2005, IEC 60601-1:2005/AMD1:2012 and
IEC 60601-1:2005/AMD2:2020 and the associated updates of the collateral standards.

– 8 – IEC 60601-2-33:2022 © IEC 2022
MEDICAL ELECTRICAL EQUIPMENT –

Part 2-33: Particular requirements for the basic safety and essential
performance of magnetic resonance equipment for medical diagnosis

201.1 Scope, object and related standards
Clause 1 of IEC 60601-1:2005, IEC 60601-1:2005/AMD1:2012 and
IEC 60601-1:2005/AMD2:2020 applies, except as follows:
201.1.1 Scope
Replacement:
This document applies to the BASIC SAFETY and ESSENTIAL PERFORMANCE of MAGNETIC
RESONANCE (MR) EQUIPMENT and MAGNETIC RESONANCE (MR) SYSTEMS.
NOTE Where ME EQUIPMENT and ME SYSTEMS are used in the clause headings, this is to be understood to indicate
MR EQUIPMENT and MR SYSTEMS.
This document does not cover the application of MR EQUIPMENT beyond the INTENDED USE.
If a clause or subclause is specifically intended to be applicable to MR EQUIPMENT only, or to
MR SYSTEMS only, the title and content of that clause or subclause will say so. If that is not the
case, the clause or subclause applies both to MR EQUIPMENT and to MR SYSTEMS, as relevant.
This document does not formulate additional specific requirements for MR EQUIPMENT or
MR SYSTEMS used in INTERVENTIONAL MR EXAMINATIONS.
201.1.2 Object
Replacement:
The object of this document is to establish particular BASIC SAFETY and ESSENTIAL PERFORMANCE
requirements for MR EQUIPMENT to provide protection for the PATIENT and the MR WORKER.
NOTE This document presumes that the MR WORKERs are screened, trained and instructed in their duties.
201.1.3 Collateral standards
Addition:
This document refers to those applicable collateral standards that are listed in Clause 2 of
IEC 60601-1:2005, IEC 60601-1:2005/AMD1:2012 and IEC 60601-1:2005/AMD2:2020 and
Clause 201.2 of this document.
IEC 60601-1-2:2014 and IEC 60601-1-2:2014/AMD1:2020 applies as modified in Clause 202.
IEC 60601-1-3 [1], IEC 60601-1-9 [2], IEC 60601-1-10 [3], IEC 60601-1-11 [4] and
IEC 60601-1-12 [5] do not apply. All other published collateral standards in the IEC 60601-1
series apply as published.
IEC 60601-2-33:2022 © IEC 2022 – 9 –
201.1.4 Particular standards
Addition:
In the IEC 60601 series, particular standards may modify, replace or delete requirements
contained in the general standard and collateral standards as appropriate for the particular
ME EQUIPMENT under consideration, and may add other BASIC SAFETY and ESSENTIAL
PERFORMANCE requirements.
A requirement of a particular standard takes priority over the general standard, viz.
IEC 60601-1:2005, IEC 60601-1:2005/AMD1:2012 and IEC 60601-1:2005/AMD2:2020.
Collateral standards are referred to by their document number.
The numbering of clauses and subclauses of this document corresponds to that of the general
standard with the prefix "201" (e.g. 201.1 in this document addresses the content of Clause 1
of the general standard) or applicable collateral standard with the prefix "20x" where x is the
final digit(s) of the collateral standard document number (e.g. 202.4 in this document addresses
the content of Clause 4 of the 60601-1-2 collateral standard, 208.4 in this document addresses
the content of Clause 4 of the 60601-1-8 collateral standard, etc.). The changes to the text of
the general standard are specified by the use of the following words:
"Replacement" means that the clause or subclause of the general standard or applicable
collateral standard is replaced completely by the text in this document.
"Addition" means that the text of this document is additional to the requirements of the general
standard or applicable collateral standard.
"Amendment" means that the clause or subclause of the general standard or applicable
collateral standard is amended as indicated by the text of this document.
Subclauses, figures or tables which are additional to those of the general standard are
numbered starting from 201.101. However due to the fact that definitions in the general standard
are numbered 3.1 through 3.154, additional definitions in this document are numbered
beginning from 201.3.201. Additional annexes are lettered AA, BB, etc., and additional items
aa), bb), etc.
Subclauses, figures or tables which are additional to those of a collateral standard are
numbered starting from 20x, where "x" is the number of the collateral standard, e.g. 202 for
IEC 60601-1-2, 203 for IEC 60601-1-3, etc.
The term "this document" is used to make reference to IEC 60601-1:2005,
IEC 60601-1:2005/AMD1:2012 and IEC 60601-1:2005/AMD2:2020, any applicable collateral
standards and this document taken together.
Where there is no corresponding clause or subclause in this document, the clause or subclause
of the general standard or applicable collateral standard, although possibly not relevant, applies
without modification; where it is intended that any part of the general standard or applicable
collateral standard, although possibly relevant, is not to be applied, a statement to that effect
is given in this document.
201.2 Normative references
NOTE Informative references are listed in the bibliography beginning on page 130.
Clause 2 of IEC 60601-1:2005, IEC 60601-1:2005/AMD1:2012 and IEC 60601-1:2005/AMD2:2020
applies except as follows:
– 10 – IEC 60601-2-33:2022 © IEC 2022
Replacement:
IEC 60601-1-2:2014, Medical electrical equipment – Part 1-2: General requirements for basic
safety and essential performance – Collateral Standard: Electromagnetic disturbances –
Requirements and tests
IEC 60601-1-2:2014/AMD1:2020
Addition:
IEC 60601-1:2005, Medical electrical equipment – Part 1: General requirements for basic safety
and essential performance
IEC 60601-1:2005/AMD1:2012
IEC 60601-1:2005/AMD2:2020
IEC 60695-11-10:2013, Fire hazard testing – Part 11-10: Test flames – 50 W horizontal and
vertical flame test methods
IEC 61672-1:2013, Electroacoustics – Sound level meters – Part 1: Specifications
IEC 61672-2:2013, Electroacoustics – Sound level meters – Part 2: Pattern evaluation tests
IEC 62570:2014, Standard practice for marking devices and other items for safety in the
magnetic resonance environment
ISO 3746:2010, Acoustics – Determination of sound power levels and sound energy levels of
noise sources using sound pressure – Survey method using an enveloping measurement
surface over a reflecting plane
ISO 9614-1, Acoustics – Determination of sound power levels of noise sources using sound
intensity – Part 1: Measurement at discrete points
NEMA MS 4, Acoustic noise measurement procedure for diagnostic magnetic resonance
equipment
NEMA MS 8, Characterization of the Specific Absorption Rate (SAR) for magnetic resonance
imaging systems
NEMA MS 14, Characterization of radiofrequency (RF) coil heating in magnetic resonance
imaging systems
201.3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 60601-1:2005,
IEC 60601-1:2005/AMD1:2012 and IEC 60601-1:2005/AMD2:2020, and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
NOTE An index of defined terms is found beginning on page 142.

IEC 60601-2-33:2022 © IEC 2022 – 11 –
Addition:
* 201.3.201
AMBIENT TEMPERATURE
temperature of the air flowing through the PATIENT environment
201.3.202
B HAZARD AREA
space around the MR EQUIPMENT where the static magnetic field can cause HARM
Note 1 to entry: The B HAZARD AREA is not identical to the SPECIAL ENVIRONMENT as defined in IEC 60601-1-2.
Note 2 to entry: The B HAZARD AREA is not identical to the MR ENVIRONMENT as defined in IEC 62570.
* 201.3.203
+
B
component of the RF magnetic field in the rotating frame that is effective for tilting of the nuclear
magnetization
+
Note 1 to entry: B is derived from the flip angle estimated from the MR signal as detected from an adjustment
volume, which is typically represented by an axial slab passing through MR ISOCENTRE.
Note 2 to entry: The spatially-localized amplitude of total B , especially in the off-centre position, can exceed the
+
VALUE of B by up to an order of magnitude.
(spatially averaged and local)
201.3.204
+
B PEAK
+
maximum VALUE of B
* 201.3.205
+
B RMS
+
root mean square (RMS) of B , which represents the highest average VALUE for any 10 s period,
evaluated over the duration of the sequence:
t
x
+
(B (t)) dt
+ ∫
B RMS=
t
x
where t is time, and t is the integration time
x
Note 1 to entry: When a sequence is shorter than 10 s, the integration time equals the sequence duration, unless
sliding window continuous integration across sequences is used.
* 201.3.206
|dB/dt| PEAK
maximum time rate of change of the magnitude of the magnetic field generated by the combined
outputs of the GRADIENT UNITS during the MR EXAMINATION, evaluated at the COMPLIANCE VOLUME
201.3.207
CIRCULARLY POLARIZED DRIVE
CP
RF excitation where the two principal electromagnetic modes of a birdcage VOLUME RF TRANSMIT
COIL are driven with equal amplitude and 90° phase difference
Note 1 to entry: CIRCULARLY POLARIZED DRIVE is also commonly referred to as "quadrature drive" or "circularly
polarized" and can be used interchangeably.

– 12 – IEC 60601-2-33:2022 © IEC 2022
–
Note 2 to entry: CP into a loaded coil does not necessarily result in the lowest possible counter-rotating B
component.
Note 3 to entry: A coil operating in CP can additionally use a single mode, linearly-polarized excitation if the
exposure is infrequent, short, and does not exceed 50 % power drive for CP.
Note 4 to entry: Transverse electromagnetic (TEM) coils can be characterized as CP by using additional qualification
and controls.
201.3.208
CIRCULARLY POLARIZED RF
time-varying B field, where the field vector describes a circular trajectory in a plane orthogonal
to the static magnetic field vector
Note 1 to entry: The polarity of the magnet determines the direction in which the generated B field rotates to
+
generate MR signals (that is, the B component).
─
Note 2 to entry: A small B component (rotating in the opposite direction) is unavoidable in real-world
implementations of VOLUME RF TRANSMIT COILS when using CIRCULARLY POLARIZED DRIVE. The consequence is that
the generated time-varying B field vector deviates slightly from the ideal circular trajectory.
201.3.209
COMPLIANCE VOLUME
space in which compliance of GRADIENT OUTPUT is inspected
Note 1 to entry: In CYLINDRICAL MR EQUIPMENT with a WHOLE BODY MAGNET, the COMPLIANCE VOLUME is a cylinder
with its axis coinciding with the PATIENT’s axis and with a radius of 0,20 m and with a length equal to the length of
the gradient coil.
Note 2 to entry: In MR EQUIPMENT with a TRANSVERSE FIELD MAGNET and a WHOLE BODY GRADIENT SYSTEM, the
COMPLIANCE VOLUME is a cylinder aligned with the PATIENT’s axis, of length equal to the gradient coil diameter, and a
radius of 0,20 m or equal to half the distance between the poles of the magnet, whichever is less.
Note 3 to entry: In all other MR SYSTEMS, the COMPLIANCE VOLUME is the volume where any part of a PATIENT body
can be properly located according to the INTENDED USE of the MR EQUIPMENT.
* 201.3.210
CORE TEMPERATURE
temperature of the internal organs in the body and the aortic blood
* 201.3.211
CUMULATIVE EQUIVALENT MINUTES AT 43 °C
CEM43
duration of exposure at a constant temperature of 43 °C required to produce the magnitude of
a thermally induced bio-effect, i.e., an "iso-effect", as is produced by an exposure of duration
t at a different temperature T that can vary in time; defined mathematically as:
exam
t
exam
k (43−T (τ ))
CEM 43= R dτ
∫
where
-1
k = (1 °C) , a constant to render the exponent dimensionless;
T(τ) = temperature in °C during time course τ of an MR EXAMINATION;
τ = time (in min);
t = duration (in min) of the MR EXAMINATION, including the time after the last RF exposure, during which the
exam
temperature returns to physiological baseline;
R = exponential constant: 0,25 for T < 43 °C and 0,5 for T ≥ 43 °C.
Note 1 to entry: This definition has been adapted from THERMALLY EQUIVALENT TIME, as defined in IEC 60601-2-62
[160].
Note 2 to entry: Temperature can vary throughout the body.

IEC 60601-2-33:2022 © IEC 2022 – 13 –
Note 3 to entry: CEM43 has been used in hyperthermia treatments to predict cell death as the thermally-induced
bio-effect, it is not a proven metric for thermal protection.
201.3.212
CYLINDRICAL MR EQUIPMENT
MR EQUIPMENT with a substantially cylindrical PATIENT aperture, and a static magnetic field
aligned with the long axis of the cylinder
Note 1 to entry: This is inclusive of elliptical PATIENT aperture
...