IEC 60601-2-33:2010

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

IEC 60601-2-33:2010 establishes particular basic safety and essential performance requirements for magnetic resonance equipment to provide protection for the patient and the magnetic resonance worker. This third edition cancels and replaces the second edition published in 2002, its Amendment 1 (2005) and Amendment 2 (2007) and constitutes a technical revision. This third edition of IEC 60601-2-33 is based on the second amendment to Edition 2. It has also been adapted to the third edition of IEC 60601-1 (2005), with technical modifications being introduced where appropriate. The contents of the corrigenda of March 2012 and February 2016 have been included in this copy.

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

La CEI 60601-2-33:2010 établit des exigences particulières relatives à la sécurité de base et aux performances essentielles pour les appareils à résonance magnétique en matière de protection pour le patient et le personnel pour la résonance magnétique. Cette troisième édition annule et remplace la deuxième édition parue en 2002, son Amendement 1 (2005) et son Amendement 2 (2007), et constitue une révision technique. Cette troisième édition de la CEI 60601-2-33 est basée sur le deuxième amendement de l'Edition 2. Elle a également été adaptée à la troisième édition de la CEI 60601-1 (2005), des modifications techniques ayant été introduites le cas échéant. Le contenu du corrigendum de mars 2012 et février 2016 a été pris en considération dans cet exemplaire.

General Information

• Status: Published
• Publication Date: 09-Mar-2010
• ICS: 11.040.55 - Diagnostic equipment
• Technical Committee: SC 62B - Medical imaging equipment, software, and systems
• Drafting Committee: MT 40 - TC 62/SC 62B/MT 40
• Current Stage: DELPUB - Deleted Publication
• Start Date: 04-Aug-2022
• Completion Date: 17-Jul-2020

Relations

• Amended By: IEC 60601-2-33:2010/AMD1:2013 - Amendment 1 - Medical electrical equipment - Part 2-33: Particular requirements for the basic safety and essential performance of magnetic resonance equipment for medical diagnosis
• Effective Date: 05-Sep-2023
• Amended By: IEC 60601-2-33:2010/AMD2:2015 - Amendment 2 - Medical electrical equipment - Part 2-33: Particular requirements for the basic safety and essential performance of magnetic resonance equipment for medical diagnosis
• Effective Date: 05-Sep-2023
• Corrected By: IEC 60601-2-33:2010/COR2:2016 - Corrigendum 2 - Medical electrical equipment - Part 2-33: Particular requirements for the basic safety and essential performance of magnetic resonance equipment for medical diagnosis
• Effective Date: 05-Sep-2023
• Corrected By: IEC 60601-2-33:2010/COR1:2012 - Corrigendum 1 - Medical electrical equipment - Part 2-33: Particular requirements for the basic safety and essential performance of magnetic resonance equipment for medical diagnosis
• Effective Date: 05-Sep-2023
• Revised: 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
• Effective Date: 05-Sep-2023
• Revises: IEC 60601-2-33:2002 - Medical electrical equipment - Part 2-33: Particular requirements for the safety of magnetic resonance equipment for medical diagnosis
• Effective Date: 05-Sep-2023
• Revises: IEC 60601-2-33:2002/AMD1:2005 - Amendment 1 - Medical electrical equipment - Part 2-33: Particular requirements for the safety of magnetic resonance equipment for medical diagnosis
• Effective Date: 05-Sep-2023
• Revises: IEC 60601-2-33:2002/AMD2:2007 - Amendment 2 - Medical electrical equipment - Part 2-33: Particular requirements for the safety of magnetic resonance equipment for medical diagnosis
• Effective Date: 05-Sep-2023

Overview

IEC 60601-2-33:2010 is an international standard published by the International Electrotechnical Commission (IEC) that specifies the particular requirements for the basic safety and essential performance of magnetic resonance (MR) equipment used for medical diagnosis. This standard ensures protection for both patients and operators during the use of magnetic resonance imaging (MRI) systems. The 2010 edition represents the third edition, revising the previous editions and amendments to incorporate the latest technological advances and safety considerations in MR equipment design and operation.

This standard is critical for manufacturers, healthcare providers, and regulatory bodies involved in the development, deployment, and clinical use of MRI devices. It aligns with the core IEC 60601-1 general standard for medical electrical equipment, enhancing it with specific technical requirements for magnetic resonance technology.

Key Topics

• Basic Safety Requirements
  IEC 60601-2-33 addresses electrical, mechanical, and radiation hazards associated with MR equipment. These include protection against electrical shock, magnetically induced mechanical hazards, and radiofrequency (RF) energy exposure to patients and workers.

• Essential Performance Criteria
  The standard defines performance measures needed to ensure diagnostic effectiveness while minimizing patient risk. This includes accurate gradient waveform controls, RF coil functionality, and system output monitoring to maintain stable imaging and patient safety.

• Electromagnetic Compatibility (EMC)
  Requirements and testing guidelines ensure that MRI systems operate without causing or succumbing to electromagnetic disturbances, maintaining reliable performance in diverse clinical environments.

• Hazardous Situations and Fault Conditions
  Detailed provisions govern system behavior during malfunctions. The standard specifies protective measures and fail-safe designs to mitigate risks caused by hardware or software faults.

• Programmable Electrical Medical Systems (PEMS)
  The standard includes requirements for MRI systems incorporating programmable controls, emphasizing software reliability and verification for safety-critical functions.

• Identification, Marking, and Documentation
  Clear labeling, symbols, and comprehensive documentation are mandated to enable safe operation, maintenance, and emergency response by medical staff.

Applications

IEC 60601-2-33:2010 is essential for:

• MRI Equipment Manufacturers
  To design and certify MRI devices meeting international safety and performance requirements, facilitating market access worldwide.

• Healthcare Providers and Hospitals
  To ensure that MRI systems deployed on-site meet rigorous safety standards, protecting patients and staff from hazards such as excessive exposure to static and dynamic magnetic fields, RF radiation, and mechanical forces.

• Regulatory Authorities
  To assess compliance of MR equipment with recognized safety standards, supporting approval and surveillance of medical devices.

• Service and Maintenance Teams
  To understand the safety-related design and operational requirements, ensuring routine inspections and repairs maintain system integrity and performance.

Adhering to IEC 60601-2-33 fosters safer MRI practices, higher diagnostic confidence, and harmonization across international markets.

Related Standards

• IEC 60601-1: Medical Electrical Equipment – General Requirements
  The foundational standard covering basic safety and essential performance for all medical electrical equipment.

• IEC 60601-1-2: Electromagnetic Compatibility Requirements
  Specifies EMC requirements for medical electrical equipment, providing a baseline for the electromagnetic compatibility aspects of IEC 60601-2-33.

• IEC 60601 Series Amendments and Technical Reports
  Additional guidance and updates related to specific technologies and clinical environments complement this standard.

• ISO 13485: Quality Management Systems for Medical Devices
  Relevant to manufacturers implementing safety and performance requirements in conjunction with quality management practices.

---

Adoption of IEC 60601-2-33:2010 standardizes magnetic resonance equipment safety protocols globally, enhancing patient protection and diagnostic accuracy. It is an indispensable reference for all stakeholders in the MRI imaging field aiming to comply with best practices and regulatory norms for medical electrical devices.

Standards Content (Sample)

IEC 60601-2-33 ®
Edition 3.0 2010-03
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
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IEC 60601-2-33 ®
Edition 3.0 2010-03
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
PRICE CODE
INTERNATIONALE
XE
CODE PRIX
ICS 11.040.55 ISBN 978-2-88910-221-1
– 2 – 60601-2-33 © IEC:2010
CONTENTS
FOREWORD.54
INTRODUCTION.6H6H7
201.1 Scope, object and related standards .7H7H8
201.2 Normative references.8H8H9
201.3 Terms and definitions.9H9H10
201.4 General requirements .10H10H15
201.5 General requirements for testing of ME EQUIPMENT .11H11H15
201.6 Classification of ME EQUIPMENT and ME SYSTEMS.12H12H15
201.7 ME EQUIPMENT identification, marking and documents .13H13H16
201.8 Protection against electrical HAZARDS from ME EQUIPMENT .14H14H27
201.9 Protection against mechanical HAZARDs of ME EQUIPMENT and ME SYSTEMS.15H15H28
201.10 Protection against unwanted and excessive radiation HAZARDS .16H16H28
201.11 Protection against excessive temperatures and other HAZARDS .17H17H28
201.12 Accuracy of controls and instruments and protection against hazardous
outputs .18H18H29
201.13 HAZARDOUS SITUATIONS and fault conditions .19H19H47
201.14 PROGRAMMABLE ELECTRICAL MEDICAL SYSTEM (PEMS).20H20H47
201.15 Construction of ME EQUIPMENT .21H21H47
201.16 ME SYSTEMS .22H22H47
201.17 Electromagnetic compatibility of ME EQUIPMENT and ME SYSTEMS .23H23H47
202 Electromagnetic compatibility – Requirements and tests .24H24H48
Annexes .25H25H48
Annex D (informative) Symbols on marking.26H26H49
Annex AA (informative) Particular guidance and rationale.27H27H51
Bibliography.28H28H96
Index of defined terms used in this particular standard.29H29H104

Figure 201.101 – Gradient waveform and EFFECTIVE STIMULUS DURATION .30H30H11
Figure 201.102 – Limits for cardiac and peripheral nerve stimulation .31H31H33
Figure 201.103 – Reduction of WHOLE BODY SAR limits at high temperatures.32H32H37
Figure 201.104 – Volume for determining the spatial maximum of gradient output .33H33H43
Figure 201.105 – Volume for determining the B stray field .34H34H46
Figure 201.D.101 – Signs indicating a transmit only RF coil, transmit / receive RF coil
and a receive only RF coil.35H35H50
Figure AA.1 – Static magnetic fields: flow potentials and retardation.36H36H68
Figure AA.2 – Experimental data on PNS threshold of human volunteers in WHOLE
EQUIPMENT.37H37H83
BODY MR
Figure AA.3 – Double logarithmic plot of experimental threshold values for peripheral
nerve stimulation .38H38H84
Figure AA.4 – Response value R(t) generated by convolution of a rectangular
stimulus dB/dt and a nerve impulse response function n(t-θ).39H39H88
Figure AA.5 – Gradient waveform G, stimulus waveform dB/dt and response value R,
for a trapezoid EPI waveform starting at t = 0 .40H40H89

60601-2-33 © IEC:2010 – 3 –
Figure AA.6 – Threshold values dB/dt for two gradient waveforms, plotted against
EFFECTIVE STIMULUS DURATION .41H41H89
Figure AA.7 – Threshold value of dB/dt for a sinusoid gradient waveform, as function
of the number of half periods in the waveform.42H42H90
Figure AA.8 – SAR limits for the exposed mass of a PATIENT .43H43H93

Table 201.101 – List of symbols.44H44H15
Table 201.102 – Rheobase values per type of gradient system .45H45H32
Table 201.103 – Weight factors for summation of the maximum output O per
i
GRADIENT UNIT .46H46H34
Table 201.104 – Temperature limits.47H47H34
Table 201.105 – SAR limits for volume transmit coils .48H48H35
Table 201.106 – SAR limits for local transmit coils .49H49H36
)
Table 201.D.101 – Examples of warning signs and prohibitive signs :.50H50H49
Table AA.1 – Static field occupational standards.51H51H67

– 4 – 60601-2-33 © IEC:2010
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
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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
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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 60601-2-33 has been prepared by IEC subcommittee 62B:
Diagnostic imaging equipment, of IEC technical committee 62: Electrical equipment in medical
practice.
This third edition cancels and replaces the second edition published in 2002, its Amendment 1
(2005) and Amendment 2 (2007) and constitutes a technical revision. This third edition of
IEC 60601-2-33 is based on the second amendment to Edition 2. It has also been adapted to
the third edition of IEC 60601-1 (2005), with technical modifications being introduced where
appropriate.
60601-2-33 © IEC:2010 – 5 –
The text of this particular standard is based on the following documents:
FDIS Report on voting
62B/777/FDIS 62B/782/RVD
Full information on the voting for the approval of this particular standard can be found in the
report on voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
In this standard, 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 THE GENERAL STANDARD, IN THIS PARTICULAR STANDARD OR AS
NOTED: SMALL CAPITALS.
In referring to the structure of this standard, the term
– “clause” means one of the seventeen 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 standard are preceded by the term “Clause” followed by the
clause number. References to subclauses within this particular standard are by number only.
In this standard, 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 standard conform to usage described in Annex H of the ISO/IEC
Directives, Part 2. For the purposes of this standard, the auxiliary verb:
– “shall” means that compliance with a requirement or a test is mandatory for compliance
with this standard;
– “should” means that compliance with a requirement or a test is recommended but is not
mandatory for compliance with this standard;
– “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 series, published under the general title: Medical electrical
equipment, can be found on the IEC website.

– 6 – 60601-2-33 © IEC:2010
The committee has decided that the contents of this amendment and the base publication will
remain unchanged until the stability date indicated on the IEC web site under
"http://webstore.iec.ch" in the data related to the specific publication. At this date, the
publication will be
• reconfirmed;
• withdrawn;
• replaced by a revised edition, or
• amended.
The contents of the corrigenda 1 (March 2012) and 2 (February 2016) have been included in
this copy.
IMPORTANT – The 'colour inside' logo on the cover page of this publication 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.
60601-2-33 © IEC:2010 – 7 –
* INTRODUCTION
This particular standard is written at a moment in which the technical evolution of
MR EQUIPMENT is in rapid progress and the scientific foundation of its safe use is still
expanding.
This International Standard addresses technical aspects of the medical diagnostic MR SYSTEM
and the MR EQUIPMENT therein related to the safety of PATIENTS examined with this system, the
safety of the MR WORKER involved with its operation and the safety of the MR WORKER involved
with the development, manufacturing, installation, and servicing of the MR SYSTEM. Where
limits of electromagnetic fields (EMF) exposure of PATIENTS and MR WORKERS are stated, these
limits do not imply that such levels of exposure can be assumed to be acceptable for workers
in other professional settings and for the population at large. The limits provide a sensible
balance between RISKS for the PATIENTS and MR WORKERS and benefits for the PATIENTS.
Organizational aspects of safety are the task of the RESPONSIBLE ORGANIZATION. This task
includes adequate training of staff, rules of access to the MR SYSTEM, qualification of staff for
decisions that are related to safety, definition of medical responsibility and specific
requirements for personnel following from that responsibility when the PATIENT is in or near
the MR SYSTEM.
Examples of such organizational aspects are:
− operation in FIRST LEVEL CONTROLLED OPERATING MODE;
− emergency procedures for resuscitation of the PATIENT who is in the MR SYSTEM;
− emergency procedures after a QUENCH of the superconductive magnet when present;
− set-up and maintenance of a protocol for screening the PATIENT for contraindications or for
conditions that may affect acceptable exposure;
− rules for ROUTINE MONITORING and for MEDICAL SUPERVISION of the PATIENT during the exam.
− rules to minimize and to limit the exposure of MR WORKERS to EMF.
Extensive rationale is provided in Annex AA for some of the definitions and requirements in
order to provide the user of this standard with a reasonably complete access to the source
material that was used in support of the considerations during drafting.
The relationship of this particular standard with IEC 60601-1 and the collateral standards is
explained in subclauses 201.1.3 and 201.1.4.
The introduced EMF exposure limits required in this standard for an MR WORKER will never
exceed those allowed for PATIENTS All exposure limits allowed for a PATIENT and for an MR
WORKER are expected to protect them against negative health effects and unacceptable RISKS.
For the exposure to static magnetic fields, subjective short-term physiological and sensory
effects are expected. These influence the well being of the MR WORKER marginally and only
during or shortly after exposure.
For the exposure to GRADIENT OUTPUT and RF transmit fields, normally no short-term
physiological and sensory effects are expected for MR WORKERS.
In addition no experimental or theoretical basis for cumulative biological effects in humans,
resulting from exposure at the allowed levels has been generally accepted.
The requirements for acoustic noise exposure are different for PATIENTS and MR WORKERS.

– 8 – 60601-2-33 © IEC:2010
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
1)
Clause 1 of the general standard 1F0F applies, except as follows:
201.1.1 Scope
Replacement:
This International Standard applies to the BASIC SAFETY and ESSENTIAL PERFORMANCE of
MR EQUIPMENT and MR SYSTEMS, hereafter referred to also as ME EQUIPMENT.
This standard does not cover the application of MR EQUIPMENT beyond the INTENDED USE.
If a clause or subclause is specifically intended to be applicable to ME EQUIPMENT only, or to
ME 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 ME EQUIPMENT and to ME SYSTEMS, as relevant.
The standard does not formulate ESSENTIAL PERFORMANCE requirements related to
INTERVENTIONAL MR EXAMINATIONS.
201.1.2 Object
Replacement:
The object of this particular standard 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 standard presumes that the MR WORKERS are properly medically screened, and properly trained and
instructed in their duties.
201.1.3 Collateral standards
Addition:
This particular standard refers to those applicable collateral standards that are listed in
Clause 2 of the general standard and Clause 201.2 of this particular standard.
IEC 60601-1-2:2007 applies as modified in Clause 202. IEC 60601-1-3 and IEC 60601-1-10
do not apply. All other published collateral standards in the IEC 60601-1 series apply as
published.
201.1.4 Particular standards
Replacement:
—————————
1)
The general standard is IEC 60601-1:2005, Medical electrical equipment – Part 1: General requirements for
basic safety and essential performance

60601-2-33 © IEC:2010 – 9 –
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.
For brevity, IEC 60601-1 is referred to in this particular standard as the general standard.
Collateral standards are referred to by their document number.
The numbering of clauses and subclauses of this particular standard corresponds to that of
the general standard with the prefix “201” (e.g. 201.1 in this standard 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
particular standard addresses the content of Clause 4 of the 60601-1-2 collateral standard,
203.4 in this particular standard addresses the content of Clause 4 of the 60601-1-3 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 of this particular standard.
"Addition" means that the text of this particular standard 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 particular standard.
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 3.139, additional definitions in this standard 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 standard" is used to make reference to the general standard, any applicable
collateral standards and this particular standard taken together.
Where there is no corresponding clause or subclause in this particular standard, 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 particular standard.
201.2 Normative references
NOTE Informative references are listed in the bibliography beginning on page 52H52H96.
Clause 2 of the general standard applies except as follows:
Replacement:
– 10 – 60601-2-33  IEC:2010
IEC 60601-1-2:2007, Medical electrical equipment – Part 1-2: General requirements for basic
safety and essential performance – Collateral standard: Electromagnetic compatibility –
Requirements and tests
Addition:
IEC 60601-1:2005, Medical electrical equipment – Part 1: General requirements for basic
safety and essential performance
NEMA MS 4:2006, Acoustic noise measurements procedure for diagnostic magnetic
resonance imaging devices
NEMA MS 8:2008, Characterization of the specific absorption rate (SAR) for 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 and
the following apply:
NOTE An index of defined terms is found beginning on page 53H104. A list of symbols used in the document is
provided in Table 201.101.
Addition:
* 201.3.201
B RMS
1+
root mean square (rms) of B , the MR relevant radiofrequency magnetic induction
1+
t
x
(B (t)) dt
1

B RMS .
1
t
x
where t is time, and t is the evaluation time, and is estimated at the RF transmit coil centre.
x
201.3.202
COMPLIANCE VOLUME
PATIENT accessible space in which compliance of GRADIENT OUTPUT is inspected
In MR EQUIPMENT with a cylindrical WHOLE BODY MAGNET, the COMPLIANCE VOLUME is a cylinder
with its axis coinciding with the magnet axis and with a radius of 0,20 m. and with a length
equal to the gradient coil
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 diameter of 0,40 m or equal to the distance between the poles of
the magnet, whichever is less.
In all other MR EQUIPMENT 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.
201.3.203
CONTROLLED ACCESS AREA
area to which access is controlled for safety reasons
201.3.204
CORE TEMPERATURE
mean temperature of the body core

60601-2-33 © IEC:2010 – 11 –
NOTE Typically equal to the rectal, sublingual, or tympanic temperature. More reliable representations of CORE
TEMPERATURE are oesophageal or arterial blood temperature. Brain temperatures are CORE TEMPERATUREs.
201.3.205
EFFECTIVE STIMULUS DURATION
t
s,eff
duration of any period of the monotonic increasing or decreasing gradient, used to
describe its limits for cardiac or peripheral nerve stimulation, defined as the ratio of the
peak-to-peak field variation and the maximum value of the time derivative of the gradient
in that period (see Figure 201.101)

Graph a
G
G magnetic field gradient, T/m
G
max
G maximum of gradient, T/m
max
Graph a
t
s,eff
dB/dt
Graph b
t
s,eff
dB/dt time rate of change of magnetic field, T/m/s
t
s,eff
Graph b
(dB/dt) maximum of time rate of change

max
(dB/dt)         of magnetic field, T/m/s
max
t effective stimulus duration, s
s,eff
Time
IEC  402/10
Three periods of monotonic change of the gradient G are shown in graph a. The corresponding GRADIENT
OUTPUT dB/dt is shown in graph b and the EFFECTIVE STIMULUS DURATION t is indicated.
s,eff
Figure 201.101 – Gradient waveform and EFFECTIVE STIMULUS DURATION
201.3.206
EMERGENCY FIELD SHUT DOWN UNIT
device for de-energizing a superconducting or resistive magnet in case of an emergency
situation
* 201.3.207
ENVIRONMENTAL TEMPERATURE
temperature [°C] of a uniform (isothermal) “black” enclosure in which an occupant would
exchange the same amount of heat by radiation and convection as in the actual non-uniform
environment
NOTE For the calculation of the ENVIRONMENTAL TEMPERATURE see rationale in Annex AA.
201.3.208
FIRST LEVEL CONTROLLED OPERATING MODE
mode of operation of the MR EQUIPMENT in which one or more outputs reach a value that can
cause physiological stress to PATIENTS which needs to be controlled by MEDICAL SUPERVISION
201.3.209
GRADIENT OUTPUT
parameter characterizing the gradient performance such as rate of change of the magnitude
of the magnetic field, or electric field induced by one or more GRADIENT UNITS under specified
conditions and at a specified position

– 12 – 60601-2-33 © IEC:2010
201.3.210
GRADIENT UNIT
all gradient coils and amplifiers that together generate a magnetic field gradient along one of
the axes of the coordinate system of the MR EQUIPMENT
201.3.211
HEAD RF TRANSMIT COIL
VOLUME RF TRANSMIT COIL suitable for use in MR EQUIPMENT for a MR EXAMINATION of the
PATIENT’s head
201.3.212
HEAD SAR
SAR averaged over the mass of the head and over a specified time
* 201.3.213
INTERVENTIONAL MR EXAMINATION
MR EXAMINATION applied to guide a medical (including invasive) procedure e.g. biopsy or the
treatment of a lesion
201.3.214
ISOCENTRE
in MR EQUIPMENT null point of the spatially encoding gradients
NOTE 1 Typically this also corresponds to the region of highest magnet homogeneity
[IEC 62464-1:2007, definition 3.1.15]
NOTE 2 Typically this corresponds with the position in the system targeted for imaging.
201.3.215
LOCAL RF TRANSMIT COIL
RF transmit coil other than a VOLUME RF TRANSMIT COIL
201.3.216
LOCAL SAR
SAR averaged over any 10 g of tissue of the body and over a specified time
* 201.3.217
MAGNETIC RESONANCE
MR
resonant absorption of electromagnetic energy by an ensemble of atomic nuclei situated in a
magnetic field
201.3.218
MAGNETIC RESONANCE EQUIPMENT
MR EQUIPMENT
MEDICAL ELECTRICAL EQUIPMENT which is intended for in vivo MAGNETIC RESONANCE EXAMINATION
of a PATIENT comprising all parts in hardware and software from the SUPPLY MAINS to the
display monitor
NOTE The MR EQUIPMENT is a PROGRAMMABLE ELECTRICAL MEDICAL SYSTEM (PEMS).
201.3.219
MAGNETIC RESONANCE EXAMINATION
MR EXAMINATION
process of acquiring data by MAGNETIC RESONANCE from a PATIENT

60601-2-33 © IEC:2010 – 13 –
201.3.220
MAGNETIC RESONANCE SYSTEM
MR SYSTEM
ensemble of MR EQUIPMENT, ACCESSORIES including means for display, control, energy
supplies, and the CONTROLLED ACCESS AREA, where provided
* 201.3.221
MAGNETIC RESONANCE WORKER
MR WORKER
person that because of his/her profession has to enter the CONTROLLED ACCESS AREA or
equivalent of the MAGNETIC RESONANCE SYSTEM
NOTE Other persons, such as MR volunteers and PATIENT carers, are not covered by this definition. However,
OPERATORS and staff are included in this definition (see rationale).
201.3.222
MAXIMUM GRADIENT SLEW RATE
the rate of change of the gradient obtained by switching the GRADIENT UNIT between its
maximum specified gradient strengths G and G in the shortest possible ramp time
+max −max
obtainable under normal scan conditions
* 201.3.223
MEDICAL SUPERVISION
adequate medical management of PATIENTS who can be at RISK from some parameters of
exposure to the MR EQUIPMENT, either because of the medical condition of the PATIENT, the
levels of exposure or a combination
201.3.224
NORMAL OPERATING MODE
mode of operation of the MR EQUIPMENT in which none of the outputs have a value that can
cause physiological stress to PATIENTS
201.3.225
PARTIAL BODY SAR
SAR averaged over the mass of the body that is exposed by the VOLUME RF TRANSMIT COIL and
over a specified time
201.3.226
PNS OUTPUT
value which estimates the level of peripheral nerve stimulation (PNS) for the PATIENT
201.3.227
PNS THRESHOLD LEVEL
value of the PNS OUTPUT related to the onset of PNS sensation for the PATIENT
201.3.228
QUENCH
transition of the electrical conductivity of a coil that is carrying a current from a super-
conducting state to normal conductivity, resulting in rapid boil-off of fluid cryogen and decay
of the magnetic field
201.3.229
ROUTINE MONITORING
routine PATIENT monitoring, carried out by responsible personnel such as the OPERATOR and
staff of the MR EQUIPMENT and consisting of audio and/or visual contact, as appropriate with
the PATIENT during the MR EXAMINATION

– 14 – 60601-2-33 © IEC:2010
201.3.230
SEARCH COIL
a small diameter coil used in a compliance test to measure GRADIENT OUTPUT
201.3.231
SECOND LEVEL CONTROLLED OPERATING MODE
mode of operation of the MR EQUIPMENT in which one or more outputs reach a value that
can produce significant RISK for PATIENTS, for which explicit ethical approval is required
(i.e. a human studies protocol approved to local requirements)
201.3.232
SPECIAL PURPOSE GRADIENT SYSTEM
gradient system suitable for use in MR EQUIPMENT for a special purpose
NOTE An example of a SPECIAL PURPOSE GRADIENT SYSTEM is a gradient system that can be incorporated in
MR EQUIPMENT to allow special examination of the head of the PATIENT.
* 201.3.233
SPECIFIC ABSORPTION RATE
SAR
radio frequency power absorbed per unit of mass (W/kg)
201.3.234
TIME RATE OF CHANGE OF THE MAGNETIC FIELD
dB/dt
rate of change of the magnetic flux density with time (T/s)
201.3.235
TRANSVERSE FIELD MAGNET
magnet for which the field is at right angles to the axial direction of the PATIENT
201.3.236
VOLUME RF TRANSMIT COIL
RF transmit coil suitable for use in MR EQUIPMENT that produces a homogeneous RF field over
an extended volume encompassed by the coil
NOTE The VOLUME RF TRANSMIT COIL can be a WHOLE BODY RF TRANSMIT COIL, a HEAD RF TRANSMIT COIL or a RF
designed for homogeneous exposure of a specific part of the body. A single loop coil enclosing the
TRANSMIT COIL
body or a part of the body is considered to be a VOLUME RF TRANSMIT COIL (example: single loop wrist coil).
201.3.237
WHOLE BODY GRADIENT SYSTEM
gradient system suitable for use in WHOLE BODY MR EQUIPMENT
201.3.238
WHOLE BODY MAGNET
magnet suitable for use in WHOLE BODY MR EQUIPMENT
201.3.239
WHOLE BODY MAGNETIC RESONANCE EQUIPMENT
WHOLE BODY MR EQUIPMENT
MR EQUIPMENT of sufficient size to allow whole body MR EXAMINATION and partial body MR
EXAMINATION of adult PATIENTS. It can be equipped with VOLUME RF TRANSMIT COILS, LOCAL
RF TRANSMIT COILS and with a SPECIAL PURPOSE GRADIENT SYSTEM
201.3.240
WHOLE BODY RF TRANSMIT COIL
VOLUME RF TRANSMIT COIL of sufficient size for whole body examinations of adult PATIENTS

60601-2-33  IEC:2010 – 15 –
201.3.241
WHOLE BODY SAR
SAR averaged over the total mass of the body and over a specified time
Table 201.101 – List of symbols
Symbol SI-Unit Definition
T Static magnetic field
B
T Magnetic induction of the radio frequency magnetic field
B
1+
T
B RMS Root mean square of B
1+ 1+
T/s TIME RATE OF CHANGE OF THE MAGNETIC FIELD (dB/dt)
dB/dt
V/m Electric field induced by gradient switching
E
G T/m Magnetic field gradient
V/m or T/s Limit of the GRADIENT OUTPUT for the NORMAL OPERATING MODE
L01
V/m or T/s Limit of the GRADIENT OUTPUT for the FIRST LEVEL CONTROLLED OPERATING
L12
MODE
depending on context PNS OUTPUT
O
depending on context PNS OUTPUT per GRADIENT UNIT
O
i
V/m or T/s Rheobase
rb
W/kg SPECIFIC ABSORPTION RATE (SAR)
SAR
ms EFFECTIVE STIMULUS DURATION
t
s,eff
min Averaging time for the determination of SAR
t
SAR
o
C Temperature
T
none Weight factor per GRADIENT UNIT relating the GRADIENT OUTPUT of that unit
w
i
to the limit
201.4 General requirements
Clause 4 of the general standard applies. except as follows:
201.4.3 ESSENTIAL PERFORMANCE
Addition:
NOTE 101 No ESSENTIAL PERFORMANCE requirements have been identified for the MR EQUIPMENT within the scope
of the standard.
201.5 General requirements for testing of ME EQUIPMENT
Clause 5 of the general standard applies except as follows:
201.5.7 Humidity preconditioning treatment
Addition:
For those MR SYSTEMS that are to be used only in controlled environments, as to be specified
in the technical description, no humidity preconditioning is required.
201.6 Classification of ME EQUIPMENT and ME SYSTEMS
Clause 6 of the general standard applies.

– 16 – 60601-2-33 © IEC:2010
201.7 ME EQUIPMENT identification, marking and documents
Clause 7 of the general standard applies except as follows:
201.7.9 ACCOMPANYING DOCUMENTS
201.7.9.1 General
Addition:
The ACCOMPANYING DOCUMENTS should provide sufficient information to the RESPONSIBLE
ORGANIZATION to enable it to comply with the local regulations and requirements for exposure
limits appropriate to the PATIENT and MR WORKER.
201.7.9.2 Instructions for use
201.7.9.2.10 Messages
Replacement:
The instructions for use shall list all system messages, error messages, and fault messages
that are generated related to safety concerns unless these messages are self-explanatory.
Addition:
* 201.7.9.2.101 Instructions for use for MR EQUIPMENT
* a) Pre-screening of the PATIENT and the MR WORKER
Instructions for use shall provide clear recommendations to the RESPONSIBLE ORGANIZATION
regarding pre-screening of PATIENTS and MR WORKERS. This specifically applies to those
PATIENTS and MR WORKERS who could be placed at RISK due to their professional activity, past
medical history, present medical state and/or the physical environment of the MR EQUIPMENT.
These instructions shall indicate the need for a pre-screening programme to identify such
PATIENTS and MR WORKERS at RISK, and shall provide recommendations to adequately
safeguard these PATIENTS and MR WORKERS from injury. For the MR WORKER and the PATIENT
especially the RISK due to the past professional activity, which could have caused accidental
implantation of ferromagnetic materials, shall be considered.
The following specific classes of PATIENTS shall be mentioned:
– classes of PATIENTS for whom MR EXAMINATIONS are considered to be contraindicated;
– classes of PATIENTS having higher than normal likelihood of needing emergency medical
treatment, independent of the physical environment of the MR EQUIPMENT;
– classes of PATIENTS having a higher than normal likelihood of needing emergency medical
treatment due to the elevated values of the applied fields, when the MR EQUIPMENT is
capable of operating within the FIRST LEVEL CONTROLLED OPERATING MODE as described in
subclause 201.12.4.101.
* b) MEDICAL SUPERVISION OF PATIENTS
Instructions for use shall provide clear recommendations to the RESPONSIBLE ORGANIZATION to
establish a programme for the supervision appropriate to the classes of PATIENTS described in
201.7.9.2.101 a) and to the controlled modes of operation of the MR EQUIPMENT as defined in
201.3.208, 201.3.231 and 201.3.244.
Instructions for use shall:
60601-2-33 © IEC:2010 – 17 –
– include the recommendation that all PATIENTS should receive at least ROUTINE MONITORING;
– if the MR EQUIPMENT is capable of operating within the FIRST LEVEL CONTROLLED OPERATING
MODE: give recommendation that procedures should be established to ensure that MEDICAL
SUPERVISION is provided when entering the FIRST LEVEL CONTROLLED OPERATING MODE;
– if the MR EQUIPMENT is provided with a SECOND LEVEL CONTROLLED OPERATING MODE: include
notification that operation in the SECOND LEVEL CONTROLLED OPERATING MODE requires
approval of investigational human studies protocol according to local requirements (e.g.
ethics committee, investigational review board, etc.). In addition it shall be stated that the
local approval should specifically state limits for GRADIENT OUTPUT, SAR and static field
strength.
* c) Emergency medical procedures
Instructions for use shall give clear recommendation to the RESPONSIBLE ORGANIZATION to
define and implement specific emergency medical procedures that apply to the PATIENT and
that take into account the presence of the magnetic field, so that if during MR EXAMINATION the
PATIENT feels ill or is injured by external causes, medical treatment can be given as soon as
possible.
These instructions shall include recommendations to establish a procedure for removing
PATIENTS rapidly from the magnet's influence, if necessary, by using the EMERGENCY FIELD
SHUT DOWN UNIT.
* d) Exposure of the PATIENT and MR WORKER to excessive acoustic noise
The instructions for use:
– shall draw attention to the possibility that anaesthetised PATIENTS can have less than
normal protection against high sound pr
...

IEC 60601-2-33 ®
Edition 3.1 2013-04
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
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IEC 60601-2-33 ®
Edition 3.1 2013-04
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 978-2-8322-0783-3

– 2 – 60601-2-33  IEC:2010+A1:2013

CONTENTS
FOREWORD . 4

INTRODUCTION . 7

INTRODUCTION TO AMENDMENT 1 . 8

201.1 Scope, object and related standards . 9

201.2 Normative references . 10

201.3 Terms and definitions. 11

201.4 General requirements . 16
201.5 General requirements for testing of ME EQUIPMENT . 16
201.6 Classification of ME EQUIPMENT and ME SYSTEMS . 17
201.7 ME EQUIPMENT identification, marking and documents . 17
201.8 Protection against electrical HAZARDS from ME EQUIPMENT . 29
201.9 Protection against mechanical HAZARDs of ME EQUIPMENT and ME SYSTEMS . 29
201.10 Protection against unwanted and excessive radiation HAZARDS . 30
201.11 Protection against excessive temperatures and other HAZARDS . 30
201.12 Accuracy of controls and instruments and protection against hazardous
outputs . 30
201.13 HAZARDOUS SITUATIONS and fault conditions . 49
201.14 PROGRAMMABLE ELECTRICAL MEDICAL SYSTEM (PEMS) . 49
201.15 Construction of ME EQUIPMENT . 49
201.16 ME SYSTEMS . 49
201.17 Electromagnetic compatibility of ME EQUIPMENT and ME SYSTEMS . 49
202 Electromagnetic compatibility – Requirements and tests . 50

Annexes . 50
Annex D (informative) Symbols on marking . 51
Annex AA (informative) Particular guidance and rationale . 53

Bibliography . 98

Index of defined terms used in this particular standard. 106

Figure 201.101 – Gradient waveform and EFFECTIVE STIMULUS DURATION . 12
Figure 201.102 – Limits for cardiac and peripheral nerve stimulation . 35
Figure 201.103 – Reduction of WHOLE BODY SAR limits at high temperatures . 39
Figure 201.104 – Volume for determining the spatial maximum of gradient output . 45
Figure 201.105 – Volume for determining the B stray field . 48
Figure 201.D.101 – Signs indicating a transmit only RF coil, transmit / receive RF coil
and a receive only RF coil . 52
Figure AA.1 – Static magnetic fields: flow potentials and retardation . 70

60601-2-33  IEC:2010+A1:2013 – 3 –

Figure AA.2 – Experimental data on PNS threshold of human volunteers in WHOLE

BODY MR EQUIPMENT. 85

Figure AA.3 – Double logarithmic plot of experimental threshold values for peripheral

nerve stimulation . 86

Figure AA.4 – Response value R(t) generated by convolution of a rectangular
stimulus dB/dt and a nerve impulse response function n(t-θ) . 90

Figure AA.5 – Gradient waveform G, stimulus waveform dB/dt and response value R,

for a trapezoid EPI waveform starting at t = 0 . 91

Figure AA.6 – Threshold values dB/dt for two gradient waveforms, plotted against

EFFECTIVE STIMULUS DURATION . 91

Figure AA.7 – Threshold value of dB/dt for a sinusoid gradient waveform, as function
of the number of half periods in the waveform . 92
Figure AA.8 – SAR limits for the exposed mass of a PATIENT . 95

Table 201.101 – List of symbols . 16
Table 201.102 – Rheobase values per type of gradient system . 34
Table 201.103 – Weight factors for summation of the maximum output O per
i
GRADIENT UNIT . 36
Table 201.104 – Temperature limits . 36
Table 201.105 – SAR limits for volume transmit coils . 37
Table 201.106 – SAR limits for local transmit coils . 38
Table 201.D.101 – Examples of warning signs and prohibitive signs . 51
Table AA.1 – Static field occupational standards . 69

– 4 – 60601-2-33 © IEC:2010+A1:2013

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
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This consolidated version of IEC 60601-2-33 consists of the third edition (2010)
[documents 62B/777/FDIS and 62B/782/RVD], its corrigenda 1 (March 2012) and 2
(February 2016), and its amendment 1 (2013) [documents 62B/884/CDV and
62B/904/RVC]. It bears the edition number 3.1.
The technical content is therefore identical to the base edition and its amendment and
has been prepared for user convenience. A vertical line in the margin shows where the
base publication has been modified by amendment 1. Additions and deletions are
displayed in red, with deletions being struck through.

60601-2-33  IEC:2010+A1:2013 – 5 –

International standard IEC 60601-2-33 has been prepared by IEC subcommittee 62B:
Diagnostic imaging equipment, of IEC technical committee 62: Electrical equipment in medical

practice.
This edition of IEC 60601-2-33 is based on the second amendment to Edition 2. It has also

been adapted to the third edition of IEC 60601-1 (2005), with technical modifications being

introduced where appropriate.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.

In this standard, 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 THE GENERAL STANDARD, IN THIS PARTICULAR STANDARD OR AS
NOTED: SMALL CAPITALS.
In referring to the structure of this standard, the term
– “clause” means one of the seventeen 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 standard are preceded by the term “Clause” followed by the
clause number. References to subclauses within this particular standard are by number only.
In this standard, 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 standard conform to usage described in Annex H of the ISO/IEC
Directives, Part 2. For the purposes of this standard, the auxiliary verb:
– “shall” means that compliance with a requirement or a test is mandatory for compliance
with this standard;
– “should” means that compliance with a requirement or a test is recommended but is not
mandatory for compliance with this standard;
– “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 series, published under the general title: Medical electrical
equipment, can be found on the IEC website.

– 6 – 60601-2-33  IEC:2010+A1:2013

The committee has decided that the contents of the base publication and its amendment will
remain unchanged until the stability date indicated on the IEC web site under

"http://webstore.iec.ch" in the data related to the specific publication. At this date, the

publication will be
• reconfirmed;
• withdrawn;
• replaced by a revised edition, or

• amended.
IMPORTANT – The 'colour inside' logo on the cover page of this publication 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.
60601-2-33  IEC:2010+A1:2013 – 7 –

* INTRODUCTION
This particular standard is written at a moment in which the technical evolution of

MR EQUIPMENT is in rapid progress and the scientific foundation of its safe use is still

expanding.
This International Standard addresses technical aspects of the medical diagnostic MR SYSTEM

and the MR EQUIPMENT therein related to the safety of PATIENTS examined with this system, the

safety of the MR WORKER involved with its operation and the safety of the MR WORKER involved

with the development, manufacturing, installation, and servicing of the MR SYSTEM. Where

limits of electromagnetic fields (EMF) exposure of PATIENTS and MR WORKERS are stated, these

limits do not imply that such levels of exposure can be assumed to be acceptable for workers
in other professional settings and for the population at large. The limits provide a sensible
balance between RISKS for the PATIENTS and MR WORKERS and benefits for the PATIENTS.
Organizational aspects of safety are the task of the RESPONSIBLE ORGANIZATION. This task
includes adequate training of staff, rules of access to the MR SYSTEM, qualification of staff for
decisions that are related to safety, definition of medical responsibility and specific
requirements for personnel following from that responsibility when the PATIENT is in or near
the MR SYSTEM.
Examples of such organizational aspects are:
− operation in FIRST LEVEL CONTROLLED OPERATING MODE;
− emergency procedures for resuscitation of the PATIENT who is in the MR SYSTEM;
− emergency procedures after a QUENCH of the superconductive magnet when present;
− set-up and maintenance of a protocol for screening the PATIENT for contraindications or for
conditions that may affect acceptable exposure;
− rules for ROUTINE MONITORING and for MEDICAL SUPERVISION of the PATIENT during the exam.
− rules to minimize and to limit the exposure of MR WORKERS to EMF.
Extensive rationale is provided in Annex AA for some of the definitions and requirements in
order to provide the user of this standard with a reasonably complete access to the source
material that was used in support of the considerations during drafting.
The relationship of this particular standard with IEC 60601-1 and the collateral standards is
explained in subclauses 201.1.3 and 201.1.4.
The introduced EMF exposure limits required in this standard for an MR WORKER will never
exceed those allowed for PATIENTS All exposure limits allowed for a PATIENT and for an MR

WORKER are expected to protect them against negative health effects and unacceptable RISKS.
For the exposure to static magnetic fields, subjective short-term physiological and sensory
effects are expected. These influence the well being of the MR WORKER marginally and only
during or shortly after exposure.
For the exposure to GRADIENT OUTPUT and RF transmit fields, normally no short-term
physiological and sensory effects are expected for MR WORKERS.
In addition no experimental or theoretical basis for cumulative biological effects in humans,
resulting from exposure at the allowed levels has been generally accepted.
The requirements for acoustic noise exposure are different for PATIENTS and MR WORKERS.

– 8 – 60601-2-33  IEC:2010+A1:2013

INTRODUCTION TO AMENDMENT 1
This amendment has been published to adapt IEC 60601-2-33:2010 to the technical

corrections introduced by Amendment 1 (2012) to IEC 60601-1:2005.

60601-2-33  IEC:2010+A1:2013 – 9 –

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

1)
Clause 1 of the general standard applies, except as follows:
201.1.1 Scope
Replacement:
This International Standard applies to the BASIC SAFETY and ESSENTIAL PERFORMANCE of
MR EQUIPMENT and MR SYSTEMS, hereafter referred to also as ME EQUIPMENT.
This standard does not cover the application of MR EQUIPMENT beyond the INTENDED USE.
If a clause or subclause is specifically intended to be applicable to ME EQUIPMENT only, or to
ME 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 ME EQUIPMENT and to ME SYSTEMS, as relevant.
The standard does not formulate ESSENTIAL PERFORMANCE requirements related to specific
requirements for MR EQUIPMENT or MR SYSTEMS used in INTERVENTIONAL MR EXAMINATIONS.
201.1.2 Object
Replacement:
The object of this particular standard 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 standard presumes that the MR WORKERS are properly medically screened, and properly trained and
instructed in their duties.
201.1.3 Collateral standards
Addition:
This particular standard refers to those applicable collateral standards that are listed in
Clause 2 of the general standard and Clause 201.2 of this particular standard.
IEC 60601-1-2:2007 applies as modified in Clause 202. IEC 60601-1-3, IEC 60601-1-10,
IEC 60601-1-11 and IEC 60601-1-12 do not apply. All other published collateral standards in
the IEC 60601-1 series apply as published.
201.1.4 Particular standards
Replacement:
—————————
1)
The general standard is IEC 60601-1:2005+A1:2012, Medical electrical equipment – Part 1: General
requirements for basic safety and essential performance

– 10 – 60601-2-33  IEC:2010+A1:2013

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.

For brevity, IEC 60601-1 is referred to in this particular standard as the general standard.

Collateral standards are referred to by their document number.

The numbering of clauses and subclauses of this particular standard corresponds to that of

the general standard with the prefix “201” (e.g. 201.1 in this standard 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
particular standard addresses the content of Clause 4 of the 60601-1-2 collateral standard,
203.4 in this particular standard addresses the content of Clause 4 of the 60601-1-3 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 of this particular standard.
"Addition" means that the text of this particular standard 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 particular standard.
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 3.139, additional definitions in this standard 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 standard" is used to make reference to the general standard, any applicable
collateral standards and this particular standard taken together.

Where there is no corresponding clause or subclause in this particular standard, 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 particular standard.
201.2 Normative references
NOTE Informative references are listed in the bibliography beginning on page 98.
Clause 2 of the general standard applies except as follows:
Replacement:
60601-2-33  IEC:2010+A1:2013 – 11 –

IEC 60601-1-2:2007, Medical electrical equipment – Part 1-2: General requirements for basic

safety and essential performance – Collateral standard: Electromagnetic compatibility –

Requirements and tests
Addition:
IEC 60601-1:2005, Medical electrical equipment – Part 1: General requirements for basic

safety and essential performance

Amendment 1:2012
NEMA MS 4:20062010, Acoustic noise measurement procedure for diagnostic magnetic

resonance imaging (MRI) devices
NEMA MS 8:2008, Characterization of the specific absorption rate (SAR) for 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
+A1:2012 and the following apply:
NOTE An index of defined terms is found beginning on page 106. A list of symbols used in the document is
provided in Table 201.101.
Addition:
* 201.3.201
B RMS
1+
root mean square (rms) of B , the MR relevant radiofrequency magnetic induction
1+
t
x
(B (t)) dt
1+
∫
B RMS = .
1+
t
x
where t is time, and t is the evaluation time, and is estimated at the RF transmit coil centre.
x
201.3.202
COMPLIANCE VOLUME
PATIENT accessible space in which compliance of GRADIENT OUTPUT is inspected
In MR EQUIPMENT with a cylindrical WHOLE BODY MAGNET, the COMPLIANCE VOLUME is a cylinder

with its axis coinciding with the magnet axis and with a radius of 0,20 m. and with a length
equal to the gradient coil
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 diameter of 0,40 m or equal to the distance between the poles of
the magnet, whichever is less.
In all other MR EQUIPMENT the COMPLIANCE VOLUME is the volume where any part of a PATIENT
INTENDED USE of the MR EQUIPMENT.
body can be properly located according to the
201.3.203
CONTROLLED ACCESS AREA
area to which access is controlled for safety reasons

– 12 – 60601-2-33  IEC:2010+A1:2013

201.3.204
CORE TEMPERATURE
mean temperature of the body core

NOTE Typically equal to the rectal, sublingual, or tympanic temperature. More reliable representations of CORE

TEMPERATURE are oesophageal or arterial blood temperature. Brain temperatures are CORE TEMPERATUREs.

201.3.205
EFFECTIVE STIMULUS DURATION
t
s,eff
duration of any period of the monotonic increasing or decreasing gradient, used to

describe its limits for cardiac or peripheral nerve stimulation, defined as the ratio of the

peak-to-peak field variation and the maximum value of the time derivative of the gradient
in that period (see Figure 201.101)

Graph a
G
G magnetic field gradient, T/m
G
max
G maximum of gradient, T/m
max
Graph a
t
s,eff
dB/dt
Graph b
t
s,eff
dB/dt time rate of change of magnetic field, T/m/s
t
s,eff
Graph b
(dB/dt) maximum of time rate of change
max
of magnetic field, T/m/s
(dB/dt)
max
t effective stimulus duration, s

s,eff
Time
IEC  402/10
Three periods of monotonic change of the gradient G are shown in graph a. The corresponding GRADIENT
OUTPUT dB/dt is shown in graph b and the EFFECTIVE STIMULUS DURATION t is indicated.
s,eff
Figure 201.101 – Gradient waveform and EFFECTIVE STIMULUS DURATION
201.3.206
EMERGENCY FIELD SHUT DOWN UNIT
device for de-energizing a superconducting or resistive magnet in case of an emergency
situation
* 201.3.207
ENVIRONMENTAL TEMPERATURE
temperature [°C] of a uniform (isothermal) “black” enclosure in which an occupant would
exchange the same amount of heat by radiation and convection as in the actual non-uniform
environment
NOTE For the calculation of the ENVIRONMENTAL TEMPERATURE see rationale in Annex AA.
201.3.208
FIRST LEVEL CONTROLLED OPERATING MODE
mode of operation of the MR EQUIPMENT in which one or more outputs reach a value that can
cause physiological stress to PATIENTS which needs to be controlled by MEDICAL SUPERVISION

60601-2-33  IEC:2010+A1:2013 – 13 –

201.3.209
GRADIENT OUTPUT
parameter characterizing the gradient performance such as rate of change of the magnitude

of the magnetic field, or electric field induced by one or more GRADIENT UNITS under specified

conditions and at a specified position

201.3.210
GRADIENT UNIT
all gradient coils and amplifiers that together generate a magnetic field gradient along one of

the axes of the coordinate system of the MR EQUIPMENT

201.3.211
HEAD RF TRANSMIT COIL
VOLUME RF TRANSMIT COIL suitable for use in MR EQUIPMENT for a MR EXAMINATION of the
PATIENT’s head
201.3.212
HEAD SAR
SAR averaged over the mass of the head and over a specified time
* 201.3.213
INTERVENTIONAL MR EXAMINATION
MR EXAMINATION applied to guide a medical (including invasive) procedure e.g. biopsy or the
treatment of a lesion
201.3.214
ISOCENTRE
in MR EQUIPMENT null point of the spatially encoding gradients
NOTE 1 Typically this also corresponds to the region of highest magnet homogeneity
[IEC 62464-1:2007, definition 3.1.15]
NOTE 2 Typically this corresponds with the position in the system targeted for imaging.
201.3.215
LOCAL RF TRANSMIT COIL
RF transmit coil other than a VOLUME RF TRANSMIT COIL
201.3.216
LOCAL SAR
SAR averaged over any 10 g of tissue of the body and over a specified time

* 201.3.217
MAGNETIC RESONANCE
MR
resonant absorption of electromagnetic energy by an ensemble of atomic nuclei situated in a
magnetic field
201.3.218
MAGNETIC RESONANCE EQUIPMENT
MR EQUIPMENT
MEDICAL ELECTRICAL EQUIPMENT which is intended for in vivo MAGNETIC RESONANCE EXAMINATION
of a PATIENT comprising all parts in hardware and software from the SUPPLY MAINS to the
display monitor
NOTE The MR EQUIPMENT is a PROGRAMMABLE ELECTRICAL MEDICAL SYSTEM (PEMS).

– 14 – 60601-2-33  IEC:2010+A1:2013

201.3.219
MAGNETIC RESONANCE EXAMINATION

MR EXAMINATION
process of acquiring data by MAGNETIC RESONANCE from a PATIENT

201.3.220
MAGNETIC RESONANCE SYSTEM
MR SYSTEM
ensemble of MR EQUIPMENT, ACCESSORIES including means for display, control, energy

supplies, and the CONTROLLED ACCESS AREA, where provided

* 201.3.221
MAGNETIC RESONANCE WORKER
MR WORKER
person that because of his/her profession has to enter the CONTROLLED ACCESS AREA or
equivalent of the MAGNETIC RESONANCE SYSTEM
NOTE Other persons, such as MR volunteers and PATIENT carers, are not covered by this definition. However,
OPERATORS and staff are included in this definition (see rationale).
201.3.222
MAXIMUM GRADIENT SLEW RATE
the rate of change of the gradient obtained by switching the GRADIENT UNIT between its
maximum specified gradient strengths G and G in the shortest possible ramp time
+max −max
obtainable under normal scan conditions
* 201.3.223
MEDICAL SUPERVISION
adequate medical management of PATIENTS who can be at RISK from some parameters of
exposure to the MR EQUIPMENT, either because of the medical condition of the PATIENT, the
levels of exposure or a combination
201.3.224
NORMAL OPERATING MODE
mode of operation of the MR EQUIPMENT in which none of the outputs have a value that can
cause physiological stress to PATIENTS
201.3.225
PARTIAL BODY SAR
SAR averaged over the mass of the body that is exposed by the VOLUME RF TRANSMIT COIL and
over a specified time
201.3.226
PNS OUTPUT
value which estimates the level of peripheral nerve stimulation (PNS) for the PATIENT
201.3.227
PNS THRESHOLD LEVEL
value of the PNS OUTPUT related to the onset of PNS sensation for the PATIENT
201.3.228
QUENCH
transition of the electrical conductivity of a coil that is carrying a current from a super-
conducting state to normal conductivity, resulting in rapid boil-off of fluid cryogen and decay
of the magnetic field
60601-2-33  IEC:2010+A1:2013 – 15 –

201.3.229
ROUTINE MONITORING
routine PATIENT monitoring, carried out by responsible personnel such as the OPERATOR and

staff of the MR EQUIPMENT and consisting of audio and/or visual contact, as appropriate with

the PATIENT during the MR EXAMINATION

201.3.230
SEARCH COIL
a small diameter coil used in a compliance test to measure GRADIENT OUTPUT

201.3.231
SECOND LEVEL CONTROLLED OPERATING MODE
mode of operation of the MR EQUIPMENT in which one or more outputs reach a value that
can produce significant RISK for PATIENTS, for which explicit ethical approval is required
(i.e. a human studies protocol approved to local requirements)
201.3.232
SPECIAL PURPOSE GRADIENT SYSTEM
gradient system suitable for use in MR EQUIPMENT for a special purpose
NOTE An example of a SPECIAL PURPOSE GRADIENT SYSTEM is a gradient system that can be incorporated in
MR EQUIPMENT to allow special examination of the head of the PATIENT.
* 201.3.233
SPECIFIC ABSORPTION RATE
SAR
radio frequency power absorbed per unit of mass (W/kg)
201.3.234
TIME RATE OF CHANGE OF THE MAGNETIC FIELD
dB/dt
rate of change of the magnetic flux density with time (T/s)
201.3.235
TRANSVERSE FIELD MAGNET
magnet for which the field is at right angles to the axial direction of the PATIENT
201.3.236
VOLUME RF TRANSMIT COIL
RF transmit coil suitable for use in MR EQUIPMENT that produces a homogeneous RF field over
an extended volume encompassed by the coil

NOTE The VOLUME RF TRANSMIT COIL can be a WHOLE BODY RF TRANSMIT COIL, a HEAD RF TRANSMIT COIL or a RF
TRANSMIT COIL designed for homogeneous exposure of a specific part of the body. A single loop coil enclosing the
body or a part of the body is considered to be a VOLUME RF TRANSMIT COIL (example: single loop wrist coil).
201.3.237
WHOLE BODY GRADIENT SYSTEM
gradient system suitable for use in WHOLE BODY MR EQUIPMENT
201.3.238
WHOLE BODY MAGNET
magnet suitable for use in WHOLE BODY MR EQUIPMENT
201.3.239
WHOLE BODY MAGNETIC RESONANCE EQUIPMENT
WHOLE BODY MR EQUIPMENT
MR EQUIPMENT of sufficient size to allow whole body MR EXAMINATION and partial body MR
EXAMINATION of adult PATIENTS. It can be equipped with VOLUME RF TRANSMIT COILS, LOCAL
RF TRANSMIT COILS and with a SPECIAL PURPOSE GRADIENT SYSTEM

– 16 – 60601-2-33  IEC:2010+A1:2013

201.3.240
WHOLE BODY RF TRANSMIT COIL
VOLUME RF TRANSMIT COIL of sufficient size for whole body examinations of adult PATIENTS

201.3.241
WHOLE BODY SAR
averaged over the total mass of the body and over a specified time
SAR
Table 201.101 – List of symbols

Symbol SI-Unit Definition
T Static magnetic field
B
T Magnetic induction of the radio frequency magnetic field
B
1+
T
B RMS Root mean square of B
1+ 1+
T/s TIME RATE OF CHANGE OF THE MAGNETIC FIELD (dB/dt)
dB/dt
V/m Electric field induced by gradient switching
E
G T/m Magnetic field gradient
V/m or T/s Limit of the GRADIENT OUTPUT for the NORMAL OPERATING MODE
L01
V/m or T/s Limit of the GRADIENT OUTPUT for the FIRST LEVEL CONTROLLED OPERATING
L12
MODE
depending on context PNS OUTPUT
O
depending on context PNS OUTPUT per GRADIENT UNIT
O
i
V/m or T/s Rheobase
rb
W/kg SPECIFIC ABSORPTION RATE (SAR)
SAR
ms EFFECTIVE STIMULUS DURATION
t
s,eff
min Averaging time for the determination of SAR
t
SAR
o
C Temperature
T
none Weight factor per GRADIENT UNIT relating the GRADIENT OUTPUT of that unit
w
i
to the limit
201.4 General requirements
Clause 4 of the general standard applies. except as follows:
201.4.3 ESSENTIAL PERFORMANCE
Addition:
NOTE 101 No ESSENTIAL PERFORMANCE requirements have been identified for the MR EQUIPMENT within the scope
of the standard. For the functions of the MR EQUIPMENT covered by this standard no specific ESSENTIAL
PERFORMANCE requirements have been identified. Other functions of the MR EQUIPMENT may constitute ESSENTIAL
PERFORMANCE. See the general standard for requirements to the RISK MANAGEMENT FILE of the MANUFACTURER to
cover the analysis of ESSENTIAL PERFORMANCE of the MR EQUIPMENT.
201.5 General requirements for testing of ME EQUIPMENT
Clause 5 of the general standard applies except as follows:
201.5.7 Humidity preconditioning treatment
Addition:
60601-2-33  IEC:2010+A1:2013 – 17 –

For those MR SYSTEMS and MR EQUIPMENT that are to be used only in controlled environments,

as to be specified in the technical description, no humidity preconditioning is required.

NOTE A controlled environment is not the same as CONTROLLED ACCESS AREA.

201.6 Classification of ME EQUIPMENT and ME SYSTEMS

Clause 6 of the general standard applies.

201.7 ME EQUIPMENT identification, marking and documents

Clause 7 of the general standard applies except as follows:
201.7.2 Marking on the outside of ME EQUIPMENT or ME EQUIPMENT parts
201.7.2.13 Physiological effects (safety signs and warning statements)
Addition:
Applicable safety signs ISO 7010-W005 and ISO 7010-W006 shall be placed at the entrance
of the CONTROLLED ACCESS AREA. The safety signs may be accompanied by text explaining that
the magnetic field is always on, but that EMF emission is restricted to the situation when the
MR EQUIPMENT is scanning.
For MR EQUIPMENT that does not require a CONTROLLED ACCESS AREA, the need for and location
of the safety signs shall be described in the RISK MANAGEMENT FILE by the MANUFACTURER.
Information shall be provided in the instructions for use concerning specific physiological
effects related to MR EQUIPMENT.
201.7.9 ACCOMPANYING DOCUMENTS
201.7.9.1 General
Addition:
The ACCOMPANYING DOCUMENTS should provide sufficient information to the RESPONSIBLE
ORGANIZATION to enable it to comply with the local regulations and requirements for exposure
PATIENT and MR WORKER.
limits appropriate to the
201.7.9.2 Instructions for use
201.7.9.2.10 Messages
Replacement:
The instructions for use shall list all system messages, error messages, and fault messages
that are generated related to safety concerns unless these messages are self-explanatory.
201.7.9.2.17 ME EQUIPMENT emitting radiation
Addition:
NOTE The instructions for use in 201.7.9.2.101 and the compatibility technical specification sheet in the technical
description in 201.7.9.3.101 provide detailed information concerning electromagnetic fields of the MR EQUIPMENT.
Addition:
– 18 – 60601-2-33  IEC:2010+A1:2013

* 201.7.9.2.101 Instructions for use for MR EQUIPMENT

* a) Pre-screening of the PATIENT and the MR WORKER

Instructions for use shall provide clear recommendations to the RESPONSIBLE ORGANIZATION

regarding pre-screening of PATIENTS and MR WORKERS. This specifically applies to those

PATIENTS and MR WORKERS who could be placed at RISK due to their professional activity, past

medical history, present medical state and/or the physical environment of the MR EQUIPMENT.

These instructions shall indicate the need for a pre-screening programme to identify such
PATIENTS and MR WORKERS at RISK, and shall provide recommendations to adequately

safeguard these PATIENTS and MR WORKERS from injury. For the MR WORKER and the PATIENT

especially the RISK due to the past professional activity, which could have caused accidental

implantation of ferromagnetic materials, shal
...

IEC 60601-2-33 ®
Edition 3.2 2015-06
CONSOLIDATED VERSION
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
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IEC 60601-2-33 ®
Edition 3.2 2015-06
CONSOLIDATED VERSION
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 978-2-8322-2743-5

IEC 60601-2-33 ®
Edition 3.2 2015-06
CONSOLIDATED VERSION
REDLINE VERSION
VERSION REDLINE
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
– 2 – IEC 60601-2-33:2010
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CONTENTS
FOREWORD . 4

* INTRODUCTION . 7

INTRODUCTION TO AMENDMENT 1 . 8

INTRODUCTION TO AMENDMENT 2 . 8

201.1 Scope, object and related standards . 9

201.2 Normative references . 10

201.3 Terms and definitions . 11
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 . 18
201.8 Protection against electrical HAZARDS from ME EQUIPMENT . 32
201.9 Protection against mechanical HAZARDs of ME EQUIPMENT and ME SYSTEMS . 32
201.10 Protection against unwanted and excessive radiation HAZARDS . 33
201.11 Protection against excessive temperatures and other HAZARDS . 33
201.12 Accuracy of controls and instruments and protection against hazardous
outputs . 33
201.13 HAZARDOUS SITUATIONS and fault conditions . 54
201.14 PROGRAMMABLE ELECTRICAL MEDICAL SYSTEM (PEMS) . 54
201.15 Construction of ME EQUIPMENT . 54
201.16 ME SYSTEMS . 54
* 201.17 Electromagnetic compatibility of ME EQUIPMENT and ME SYSTEMS . 55
* 202 Electromagnetic compatibility – Requirements and tests. 55
Annexes . 57
Annex D (informative) Symbols on marking . 58
Annex AA (informative) Particular guidance and rationale . 62
Bibliography . 119
Index of defined terms used in this particular standard . 131

Figure 201.101 – Gradient waveform and EFFECTIVE STIMULUS DURATION . 12
Figure 201.102 – Limits for cardiac and peripheral nerve stimulation . 38
Figure 201.103 – Reduction of WHOLE BODY SAR limits at high temperatures . 42
Figure 201.104 – Volume for determining the spatial maximum of gradient output . 48
Figure 201.105 – Volume for determining the B stray field . 51
Figure 201.D.101 – Signs indicating a transmit only RF coil, transmit / receive RF coil
and a receive only coil  .
Figure AA.1 – Static magnetic fields: flow potentials and retardation . 88
Figure AA.2 – Experimental data on PNS threshold of human volunteers in WHOLE
BODY MR EQUIPMENT . 104
Figure AA.3 – Double logarithmic plot of experimental threshold values for peripheral
nerve stimulation . 105
Figure AA.4 – Response value R(t) generated by convolution of a rectangular
stimulus dB/dt and a nerve impulse response function n(t-θ) . 109

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Figure AA.5 – Gradient waveform G, stimulus waveform dB/dt and response value R,

for a trapezoid EPI waveform starting at t = 0 . 110

Figure AA.6 – Threshold values dB/dt for two gradient waveforms, plotted against

EFFECTIVE STIMULUS DURATION . 110

Figure AA.7 – Threshold value of dB/dt for a sinusoid gradient waveform, as function
of the number of half periods in the waveform . 111

Figure AA.8 – SAR limits for the exposed mass of a PATIENT . 114

Table 201.101 – List of symbols and abbreviations . 17

Table 201.102 – Rheobase values per type of gradient system . 37
Table 201.103 – Weight factors for summation of the maximum output O per
i
GRADIENT UNIT . 39
Table 201.104 – Temperature limits . 39
Table 201.105 – SAR limits for volume transmit coils . 40
Table 201.106 – SAR limits for local transmit coils . 41
Table 201.107 – FPO limits applicable for cylindrical MR SYSTEMS . 52
Table 201.D.101 – Example of warning signs and prohibitive signs MR SAFETY SIGNS . 58
Table 201.D.102 – RF coil symbols . 60
Table 201.D.103 – MR conditional symbols . 61
Table AA.1 – Static field occupational standards .
Table AA.1 – Overview physiological effects in humans, animals and model systems,
for magnetic-field exposures at field strengths relevant for MRI. The implications of
the reported effects are assessed in the last column . 77

– 4 – IEC 60601-2-33:2010
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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
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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
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3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
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4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
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between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
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5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
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6) All users should ensure that they have the latest edition of this publication.
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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.

This consolidated version of the official IEC Standard and its amendments has been
prepared for user convenience.
IEC 60601-2-33 edition 3.2 contains the third edition (2010-03) [documents 62B/777/
FDIS and 62B/782/RVD], its amendment 1 (2013-04) [documents 62B/884/CDV and
62B/904/RVC] and its amendment 2 (2015-06) [documents 62B/977/FDIS and 62B/987/
RVD].
In this Redline version, a vertical line in the margin shows where the technical content
is modified by amendments 1 and 2. Additions and deletions are displayed in red, with
deletions being struck through. A separate Final version with all changes accepted is
available in this publication.

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International standard IEC 60601-2-33 has been prepared by IEC subcommittee 62B:
Diagnostic imaging equipment, of IEC technical committee 62: Electrical equipment in medical

practice.
This edition of IEC 60601-2-33 is based on the second amendment to Edition 2. It has also

been adapted to the third edition of IEC 60601-1 (2005), with technical modifications being

introduced where appropriate.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.

In this standard, 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 THE GENERAL STANDARD, IN THIS PARTICULAR STANDARD OR AS
NOTED: SMALL CAPITALS.
In referring to the structure of this standard, the term
– “clause” means one of the seventeen 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 standard are preceded by the term “Clause” followed by the
clause number. References to subclauses within this particular standard are by number only.
In this standard, 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 standard conform to usage described in Annex H of the ISO/IEC
Directives, Part 2. For the purposes of this standard, the auxiliary verb:
– “shall” means that compliance with a requirement or a test is mandatory for compliance
with this standard;
– “should” means that compliance with a requirement or a test is recommended but is not
mandatory for compliance with this standard;
– “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 series, published under the general title: Medical electrical
equipment, can be found on the IEC website.

– 6 – IEC 60601-2-33:2010
+AMD1:2013+AMD2:2015 CSV © IEC 2015

The committee has decided that the contents of the base publication and its amendments will
remain unchanged until the stability date indicated on the IEC web site under

"http://webstore.iec.ch" in the data related to the specific publication. At this date, the

publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or

• amended.
IMPORTANT – The 'colour inside' logo on the cover page of this publication 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.
+AMD1:2013+AMD2:2015 CSV  IEC 2015

* INTRODUCTION
This particular standard is written at a moment in which the technical evolution of

MR EQUIPMENT is in rapid progress and the scientific foundation of its safe use is still

expanding.
This International Standard addresses technical aspects of the medical diagnostic MR SYSTEM

and the MR EQUIPMENT therein related to the safety of PATIENTS examined with this system, the

safety of the MR WORKER involved with its operation and the safety of the MR WORKER involved

with the development, manufacturing, installation, and servicing of the MR SYSTEM. Where

limits of electromagnetic fields (EMF) exposure of PATIENTS and MR WORKERS are stated, these

limits do not imply that such levels of exposure can be assumed to be acceptable for workers
in other professional settings and for the population at large. The limits provide a sensible
balance between RISKS for the PATIENTS and MR WORKERS and benefits for the PATIENTS.
Organizational aspects of safety are the task of the RESPONSIBLE ORGANIZATION. This task
includes adequate training of staff, rules of access to the MR SYSTEM, qualification of staff for
decisions that are related to safety, definition of medical responsibility and specific
requirements for personnel following from that responsibility when the PATIENT is in or near
the MR SYSTEM.
Examples of such organizational aspects are:
− operation in FIRST LEVEL CONTROLLED OPERATING MODE;
− emergency procedures for resuscitation of the PATIENT who is in the MR SYSTEM;
− emergency procedures after a QUENCH of the superconductive magnet when present;
− set-up and maintenance of a protocol for screening the PATIENT for contraindications or for
conditions that may affect acceptable exposure;
− rules for ROUTINE MONITORING and for MEDICAL SUPERVISION of the PATIENT during the exam.
− rules to minimize and to limit the exposure of MR WORKERS to EMF.
Extensive rationale is provided in Annex AA for some of the definitions and requirements in
order to provide the user of this standard with a reasonably complete access to the source
material that was used in support of the considerations during drafting.
The relationship of this particular standard with IEC 60601-1 and the collateral standards is
explained in subclauses 201.1.3 and 201.1.4.
The introduced EMF exposure limits required in this standard for an MR WORKER will never
exceed those allowed for PATIENTS All exposure limits allowed for a PATIENT and for an MR

WORKER are expected to protect them against negative health effects and unacceptable RISKS.
For the exposure to static magnetic fields, subjective short-term physiological and sensory
effects are expected. These influence the well being of the MR WORKER marginally and only
during or shortly after exposure.
For the exposure to GRADIENT OUTPUT and RF transmit fields, normally no short-term
physiological and sensory effects are expected for MR WORKERS.
In addition no experimental or theoretical basis for cumulative biological effects in humans,
resulting from exposure at the allowed levels has been generally accepted.
The requirements for acoustic noise exposure are different for PATIENTS and MR WORKERS.

– 8 – IEC 60601-2-33:2010
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INTRODUCTION TO AMENDMENT 1
This amendment has been published to adapt IEC 60601-2-33:2010 to the technical

corrections introduced by Amendment 1 (2012) to IEC 60601-1:2005.

INTRODUCTION TO AMENDMENT 2
This Amendment 2 has been developed to increase the FIRST LEVEL CONTROLLED OPERATING

MODE limit for the static field from 4 T to 8 T taking into account FDA, ICNIRP and other peer

reviewed scientific literature. In addition, a non-compulsory option, FIXED PARAMETER

OPTION:BASIC (FPO:B), is introduced to limit RF and gradient field outputs (peak and RMS) for
scanning PATIENTS with MR conditional implants. Consequently, text is proposed for the
Instructions for use to guide users in scanning PATIENTS with MR conditional implants.
Furthermore, references to newly published collateral standards have been updated.

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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

1)
Clause 1 of the general standard applies, except as follows:
201.1.1 Scope
Replacement:
This International Standard applies to the BASIC SAFETY and ESSENTIAL PERFORMANCE of
MR EQUIPMENT and MR SYSTEMS, hereafter referred to also as ME EQUIPMENT.
This standard does not cover the application of MR EQUIPMENT beyond the INTENDED USE.
If a clause or subclause is specifically intended to be applicable to ME EQUIPMENT only, or to
ME 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 ME EQUIPMENT and to ME SYSTEMS, as relevant.
The standard does not formulate ESSENTIAL PERFORMANCE requirements related to specific
requirements for MR EQUIPMENT or MR SYSTEMS used in INTERVENTIONAL MR EXAMINATIONS.
201.1.2 Object
Replacement:
The object of this particular standard 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 standard presumes that the MR WORKERS are properly medically screened, and properly trained and
instructed in their duties.
201.1.3 Collateral standards
Addition:
This particular standard refers to those applicable collateral standards that are listed in
Clause 2 of the general standard and Clause 201.2 of this particular standard.
IEC 60601-1-2:2007 2014 applies as modified in Clause 202. IEC 60601-1-3, IEC 60601-1-10,
IEC 60601-1-11 and IEC 60601-1-12 do not apply. All other published collateral standards in
the IEC 60601-1 series apply as published.
201.1.4 Particular standards
Replacement:
—————————
1)
The general standard is IEC 60601-1:2005+A1:2012, Medical electrical equipment – Part 1: General
requirements for basic safety and essential performance

– 10 – IEC 60601-2-33:2010
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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.

For brevity, IEC 60601-1 is referred to in this particular standard as the general standard.

Collateral standards are referred to by their document number.

The numbering of clauses and subclauses of this particular standard corresponds to that of

the general standard with the prefix “201” (e.g. 201.1 in this standard 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
particular standard addresses the content of Clause 4 of the 60601-1-2 collateral standard,
203.4 in this particular standard addresses the content of Clause 4 of the 60601-1-3 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 of this particular standard.
"Addition" means that the text of this particular standard 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 particular standard.
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 3.139, additional definitions in this standard 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 standard" is used to make reference to the general standard, any applicable
collateral standards and this particular standard taken together.

Where there is no corresponding clause or subclause in this particular standard, 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 particular standard.
201.2 Normative references
NOTE Informative references are listed in the bibliography beginning on page 119.
Clause 2 of the general standard applies except as follows:
Replacement:
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IEC 60601-1-2:2007 2014, Medical electrical equipment – Part 1-2: General requirements for

basic safety and essential performance – Collateral standard: Electromagnetic compatibility

disturbances – Requirements and tests

IEC 60601-1-6:2010, Medical electrical equipment – Part 1-6: General requirements for basic

safety and essential performance – Collateral standard: Usability

IEC 60601-1-6:2010/AMD1:2013
IEC 60601-1-8:2006, Medical electrical equipment – Part 1-8: General requirements for basic

safety and essential performance – Collateral standard: General requirements, tests and

guidance for alarm systems in medical electrical equipment and medical electrical systems

IEC 60601-1-8:2006/AMD1:2012
Addition:
IEC 60601-1:2005, Medical electrical equipment – Part 1: General requirements for basic
safety and essential performance
Amendment 1:2012
NEMA MS 4:2006 2010, Acoustic noise measurement procedure for diagnostic magnetic
resonance imaging (MRI) devices
NEMA MS 8:2008, Characterization of the specific absorption rate (SAR) for 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
+A1:2012 and the following apply:
NOTE An index of defined terms is found beginning on page 53H131104. A list of symbols used in the document is
provided in Table 201.101.
Addition:
* 201.3.201
B RMS
1+
root mean square (rms) of B , the MR relevant radiofrequency magnetic induction
1+
t
x
(B (t)) dt
1

B RMS .
1
t
x
where t is time, and t is the evaluation integration time, and is estimated at the RF transmit
x
coil centre which shall be any 10 s period over the duration of the entire sequence.
Note 1 to entry: B is derived from the flip angle averaged over an adjustment volume, which is typically
1
represented by the axial central slab wherein MR signal is generated.
201.3.202
COMPLIANCE VOLUME
PATIENT accessible space in which compliance of GRADIENT OUTPUT is inspected
In MR EQUIPMENT with a cylindrical WHOLE BODY MAGNET, the COMPLIANCE VOLUME is a cylinder
with its axis coinciding with the magnet axis and with a radius of 0,20 m. and with a length
equal to the gradient coil
– 12 – IEC 60601-2-33:2010
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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 diameter of 0,40 m or equal to the distance between the poles of

the magnet, whichever is less.

In all other MR EQUIPMENT 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.

201.3.203
CONTROLLED ACCESS AREA
area around the MR SYSTEM, to which access is controlled for safety reasons to prevent HARM

from the magnetic field
Note 1 to entry: The CONTROLLED ACCESS AREA is not identical to the SPECIAL ENVIRONMENT or SPECIAL LOCATION
as defined in IEC 60601-1-2:2014.
201.3.204
CORE TEMPERATURE
mean temperature of the body core
NOTE Typically equal to the rectal, sublingual, or tympanic temperature. More reliable representations of CORE
TEMPERATURE are oesophageal or arterial blood temperature. Brain temperatures are CORE TEMPERATUREs.
201.3.205
EFFECTIVE STIMULUS DURATION
t
s,eff
duration of any period of the monotonic increasing or decreasing gradient, used to
describe its limits for cardiac or peripheral nerve stimulation, defined as the ratio of the
peak-to-peak field variation and the maximum value of the time derivative of the gradient
in that period (see Figure 201.101)

Graph a
G
G magnetic field gradient, T/m
G
max
G maximum of gradient, T/m
max
Graph a
t
s,eff
dB/dt
Graph b
t
s,eff
dB/dt time rate of change of magnetic field, T/m/s
t
s,eff
Graph b
(dB/dt) maximum of time rate of change

max
(dB/dt)         of magnetic field, T/m/s
max
t effective stimulus duration, s
s,eff
Time
IEC  402/10
Three periods of monotonic change of the gradient G are shown in graph a. The corresponding GRADIENT
OUTPUT dB/dt is shown in graph b and the EFFECTIVE STIMULUS DURATION t is indicated.
s,eff
Figure 201.101 – Gradient waveform and EFFECTIVE STIMULUS DURATION
201.3.206
EMERGENCY FIELD SHUT DOWN UNIT
device for de-energizing a superconducting or resistive magnet in case of an emergency
situation
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* 201.3.207
ENVIRONMENTAL TEMPERATURE
temperature [°C] of a uniform (isothermal) “black” enclosure in which an occupant would

exchange the same amount of heat by radiation and convection as in the actual non-uniform

environment
NOTE For the calculation of the ENVIRONMENTAL TEMPERATURE see rationale in Annex AA.

201.3.208
FIRST LEVEL CONTROLLED OPERATING MODE

mode of operation of the MR EQUIPMENT in which one or more outputs reach a value that can

cause physiological stress to PATIENTS which needs to be controlled by MEDICAL SUPERVISION

201.3.209
GRADIENT OUTPUT
parameter characterizing the gradient performance such as rate of change of the magnitude
of the magnetic field, or electric field induced by one or more GRADIENT UNITS under specified
conditions and at a specified position
201.3.210
GRADIENT UNIT
all gradient coils and amplifiers that together generate a magnetic field gradient along one of
the axes of the coordinate system of the MR EQUIPMENT
201.3.211
HEAD RF TRANSMIT COIL
VOLUME RF TRANSMIT COIL suitable for use in MR EQUIPMENT for a MR EXAMINATION of the
PATIENT’s head
201.3.212
HEAD SAR
SAR averaged over the mass of the head and over a specified time
* 201.3.213
INTERVENTIONAL MR EXAMINATION
MR EXAMINATION applied to guide a medical (including invasive) procedure e.g. biopsy or the
treatment of a lesion
201.3.214
ISOCENTRE
in MR EQUIPMENT null point of the spatially encoding gradients

NOTE 1 Typically this also corresponds to the region of highest magnet homogeneity
[IEC 62464-1:2007, definition 3.1.15]
NOTE 2 Typically this corresponds with the position in the system targeted for imaging.
201.3.215
LOCAL RF TRANSMIT COIL
RF transmit coil other than a VOLUME RF TRANSMIT COIL
201.3.216
LOCAL SAR
SAR averaged over any 10 g of tissue of the body and over a specified time

– 14 – IEC 60601-2-33:2010
+AMD1:2013+AMD2:2015 CSV  IEC 2015

* 201.3.217
MAGNETIC RESONANCE
MR
resonant absorption of electromagnetic energy by an ensemble of atomic nuclei situated in a

magnetic field
201.3.218
MAGNETIC RESONANCE EQUIPMENT
MR EQUIPMENT
MEDICAL ELECTRICAL EQUIPMENT which is intended for in vivo MAGNETIC RESONANCE EXAMINATION
of a PATIENT comprising all parts in hardware and software from the SUPPLY MAINS to the

display monitor
NOTE The MR EQUIPMENT is a PROGRAMMABLE ELECTRICAL MEDICAL SYSTEM (PEMS).
201.3.219
MAGNETIC RESONANCE EXAMINATION
MR EXAMINATION
process of acquiring data by MAGNETIC RESONANCE from a PATIENT
201.3.220
MAGNETIC RESONANCE SYSTEM
MR SYSTEM
ensemble of MR EQUIPMENT, ACCESSORIES including means for display, control, energy
supplies, and the CONTROLLED ACCESS AREA, where provided
* 201.3.221
MAGNETIC RESONANCE WORKER
MR WORKER
person that because of his/her profession has to enter the CONTROLLED ACCESS AREA or
equivalent of the MAGNETIC RESONANCE SYSTEM
NOTE Other persons, such as MR volunteers and PATIENT carers, are not covered by this definition. However,
OPERATORS and staff are included in this definition (see rationale).
201.3.222
MAXIMUM GRADIENT SLEW RATE
the rate of change of the gradient obtained by switching the GRADIENT UNIT between its
maximum specified gradient strengths G and G in the shortest possible ramp time
+max −max
obtainable under normal scan conditions
* 201.3.223
MEDICAL SUPERVISION
adequate medical management of PATIENTS who can be at RISK from some parameters of
exposure to the MR EQUIPMENT, either because of the medical condition of the PATIENT, the
levels of exposure or a combination
201.3.224
NORMAL OPERATING MODE
mode of operation of the MR EQUIPMENT in which none of the outputs have a value that can
cause physiological stress to PATIENTS
201.3.225
PARTIAL BODY SAR
SAR averaged over the mass of the body that is exposed by the VOLUME RF TRANSMIT COIL and
over a specified time
201.3.226
PNS OUTPUT
value which estimates the level of peripheral nerve stimulation (PNS) for the PATIENT

+AMD1:2013+AMD2:2015 CSV  IEC 2015

201.3.227
PNS THRESHOLD LEVEL
value of the PNS OUTPUT related to the onset of PNS sensation for the PATIENT

201.3.228
QUENCH
transition of the electrical conductivity of a coil that is carrying a current from a super-

conducting state to normal conductivity, resulting in rapid boil-off of fluid cryogen and decay

of the magnetic field
201.3.229
ROUTINE MONITORING
routine PATIENT monitoring, carried out by responsible personnel such as the OPERATOR and
staff of the MR EQUIPMENT and consisting of audio and/or visual contact, as appropriate with
the PATIENT during the MR EXAMINATION
201.3.230
SEARCH COIL
a small diameter coil used in a compliance test to measure GRADIENT OUTPUT
201.3.231
SECOND LEVEL CONTROLLED OPERATING MODE
mode of operation of the MR EQUIPMENT in which one or more outputs reach a value that
can produce significant RISK for PATIENTS, for which explicit ethical approval is required
(i.e. a human studies protocol approved to local requirements)
201.3.232
SPECIAL PURPOSE GRADIENT SYSTEM
gradient system suitable for use in MR EQUIPMENT for a special purpose
NOTE An example of a SPECIAL PURPOSE GRADIENT SYSTEM is a gradient system that can be incorporated in
MR EQUIPMENT to allow special examination of the head of the PATIENT.
* 201.3.233
SPECIFIC ABSORPTION RATE
SAR
radio frequency power absorbed per unit of mass (W/kg)
201.3.234
TIME RATE OF CHANGE OF THE MAGNETIC FIELD
dB/dt
rate of change of the magnetic flux density with time (T/s)

Note 1 to entry: The time rate of change of the magnetic field dB/dt is assumed to be evaluated in a suitably low
frequency range (e.g.  5 kHz) to disregard effects of switching amplifier ripple.
201.3.235
TRANSVERSE FIELD MAGNET
magnet for which the field is at right angles to the axial direction of the PATIENT
201.3.236
VOLUME RF TRANSMIT COIL
RF transmit coil suitable for use in MR EQUIPMENT that produces a homogeneous RF field over
an extended volume encompassed by the coil
NOTE The VOLUME RF TRANSMIT COIL can be a WHOLE BODY RF TRANSMIT COIL, a HEAD RF TRANSMIT COIL or a RF
TRANSMIT COIL designed for homogeneous exposure of a specific part of the body. A single loop coil enclosing the
body or a part of the body is considered to be a VOLUME RF TRANSMIT COIL (example: single loop wrist coil).

– 16 – IEC 60601-2-33:2010
+AMD1:2013+AMD2:2015 CSV  IEC 2015

201.3.237
WHOLE BODY GRADIENT SYSTEM
gradient system suitable for use in WHOLE BODY MR EQUIPMENT

201.3.238
WHOLE BODY MAGNET
WHOLE BODY MR EQUIPMENT
magnet suitable for use in
201.3.239
WHOLE BODY MAGNETIC RESONANCE EQUIPMENT

WHOLE BODY MR EQUIPMENT
MR EQUIPMENT of sufficient size to allow whole body MR EXAMINATION and partial body MR
EXAMINATION of adult PATIENTS. It can be equipped with VOLUME RF TRANSMIT COILS, LOCAL
TRANSMIT COILS and with a SPECIAL PURPOSE GRADIENT SYSTEM
RF
201.3.240
WHOLE BODY RF TRANSMIT COIL
VOLUME RF TRANSMIT COIL of sufficient size for whole body examinations of adult PATIENTS
201.3.241
WHOLE BODY SAR
averaged over the total mass of the body and over a specified time
SAR
201.3.242
FIXED PARAMETER
...