IEC 60601-2-37:2001

Medical electrical equipment - Part 2-37: Particular requirements for the safety of ultrasonic medical diagnostic and monitoring equipment

Establishes particular requirements for the safety of ultrasonic diagnostic equipment and those aspects thereof which are directly related to safety. Does not cover ultrasonic therapeutic equipment; however, equipment used for the imaging of body structures by ultrasound in conjunction with therapeutic modalities is covered.

General Information

• Status: Published
• Publication Date: 13-Oct-2004
• ICS: 11.040.55 - Diagnostic equipment
• ICS: 17.140.50 - Electroacoustics
• Technical Committee: SC 62B - Medical imaging equipment, software, and systems
• Drafting Committee: WG 29 - TC 62/SC 62B/WG 29
• Current Stage: DELPUB - Deleted Publication
• Start Date: 09-Aug-2007
• Completion Date: 26-Oct-2025

Relations

• Amended By: IEC 60601-2-37:2001/AMD1:2004 - Amendment 1 - Medical electrical equipment - Part 2-37: Particular requirements for the safety of ultrasonic medical diagnostic and monitoring equipment
• Effective Date: 05-Sep-2023
• Amended By: IEC 60601-2-37:2001/AMD2:2005 - Amendment 2 - Medical electrical equipment - Part 2-37: Particular requirements for the safety of ultrasonic medical diagnostic and monitoring equipment
• Effective Date: 05-Sep-2023
• Revised: IEC 60601-2-37:2007 - Medical electrical equipment - Part 2-37: Particular requirements for the basic safety and essential performance of ultrasonic medical diagnostic and monitoring equipment
• Effective Date: 05-Sep-2023

Overview

IEC 60601-2-37:2001+A1:2004 is the IEC particular standard that establishes safety requirements for ultrasonic medical diagnostic and monitoring equipment. It supplements the IEC 60601 general series by specifying hazards, test methods and information related specifically to ultrasound imaging devices. The standard covers acoustic output, electrical and mechanical safety, thermal and mechanical indices, measurement methods and marking/documentation. It does not apply to ultrasonic therapeutic equipment, although imaging performed in conjunction with therapeutic modalities is included.

Key topics and requirements

• Scope and object: Particular safety requirements for ultrasonic diagnostic equipment and related safety aspects.
• Acoustic energy & output reporting: Requirements for measuring, reporting and limiting acoustic outputs; includes tables and formats for reporting acoustic quantities.
• Output safety indices: Use and determination of the Thermal Index (TI) and Mechanical Index (MI) to communicate potential bioeffects; normative test methods and models are provided (see Annex DD, GG, HH).
• Measurement methods: Normative and informative annexes define test set-ups and methods for TI, MI, scanning output power and transducer surface temperature (Annexes DD, FF, II).
• Electrical safety & EMC: Requirements for protection against electric shock (leakage currents, dielectric strength) and electromagnetic compatibility consistent with IEC 60601-1 and IEC 60601-1-2.
• Mechanical & thermal protection: Controls on excessive temperatures, constructional safety, ingress protection, cleaning and sterilization considerations.
• Information for operator: Labelling, instructions and operator information to enable safe use and risk-informed decisions during imaging (Annex HH guidance).
• Testing and documentation: Identification, marking, and required documentation for conformity assessment and regulatory submission.

Practical applications

• Designing and validating ultrasound imaging systems, probes/transducers and monitoring units to meet international safety expectations.
• Preparing regulatory submissions and technical files for CE marking, FDA submissions or other regional approvals.
• Developing test plans and compliance reports for acoustic output, TI/MI measurement, electrical safety and EMC testing.
• Creating user manuals, labeling and operator guidance that communicate exposure indices and safe-use instructions.
• Informing clinical risk management and training for operators who must balance diagnostic benefit with patient safety.

Who uses this standard

• Medical device manufacturers (R&D, design verification, regulatory affairs)
• Independent test laboratories and conformity assessment bodies
• Regulators and notified bodies assessing ultrasound device safety
• Clinical engineers, hospital procurement and biomedical technicians
• Standards and compliance professionals working with IEC 60601 series

Related standards

• IEC 60601-1 (General requirements for safety)
• IEC 60601-1-2 (Electromagnetic compatibility)
• IEC 60601-1-4 (Programmable electrical medical systems)

Keywords: IEC 60601-2-37, ultrasonic medical diagnostic equipment, acoustic output, Thermal Index, Mechanical Index, ultrasound safety, transducer testing, medical device compliance.

Standards Content (Sample)

INTERNATIONAL IEC
STANDARD
60601-2-37
First edition
2001-07
Medical electrical equipment –
Part 2-37:
Particular requirements for the safety
of ultrasonic medical diagnostic
and monitoring equipment
Appareils électromédicaux –
Partie 2-37:
Règles particulières de sécurité pour les appareils
de diagnostic et de surveillance médicaux à ultrasons

Reference number
Publication numbering
As from 1 January 1997 all IEC publications are issued with a designation in the
60000 series. For example, IEC 34-1 is now referred to as IEC 60034-1.

Consolidated editions
The IEC is now publishing consolidated versions of its publications. For example,

edition numbers 1.0, 1.1 and 1.2 refer, respectively, to the base publication, the
base publication incorporating amendment 1 and the base publication incorporating
amendments 1 and 2.
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thus ensuring that the content reflects current technology. Information relating to
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INTERNATIONAL IEC
STANDARD
60601-2-37
First edition
2001-07
Medical electrical equipment –
Part 2-37:
Particular requirements for the safety
of ultrasonic medical diagnostic
and monitoring equipment
Appareils électromédicaux –
Partie 2-37:
Règles particulières de sécurité pour les appareils
de diagnostic et de surveillance médicaux à ultrasons

 IEC 2001  Copyright - all rights reserved
No part of this publication may be reproduced or utilized in any form or by any means, electronic or
mechanical, including photocopying and microfilm, without permission in writing from the publisher.
International Electrotechnical Commission 3, rue de Varembé Geneva, Switzerland
Telefax: [phone] e-mail: [e-mail] IEC web site http://www.iec.ch
Commission Electrotechnique Internationale
PRICE CODE
XB
International Electrotechnical Commission
For price, see current catalogue

– 2 – 60601-2-37  IEC:2001(E)

CONTENTS
FOREWORD.4

INTRODUCTION.6

SECTION ONE: GENERAL
1 Scope and object .7

2 Terminology and definitions .8

6 Identification, marking and documents .19
SECTION TWO: ENVIRONMENTAL CONDITIONS
SECTION THREE: PROTECTION AGAINST ELECTRIC SHOCK HAZARDS
19 Continuous LEAKAGE CURRENTS and PATIENT AUXILIARY CURRENTS .21
20 Dielectric strength.22
SECTION FOUR: PROTECTION AGAINST MECHANICAL HAZARDS
SECTION FIVE: PROTECTION AGAINST HAZARDS FROM UNWANTED
OR EXCESSIVE RADIATION
*35 Acoustical energy (including ultrasonic) .22
*36 Electromagnetic compatibility.22
SECTION SIX: PROTECTION AGAINST HAZARDS OF IGNITION
OF FLAMMABLE ANESTHETIC MIXTURES
SECTION SEVEN: PROTECTION AGAINST EXCESSIVE TEMPERATURES
AND OTHER SAFETY HAZARDS
42 Excessive temperatures.23
44 Overflow, spillage, leakage, humidity, ingress of liquids, cleaning, sterilization,
and disinfection .25
SECTION EIGHT: ACCURACY OF OPERATING DATA AND PROTECTION

AGAINST HAZARDOUS OUTPUT
50 Accuracy of operating data .25
51 Protection against hazardous output .26
SECTION NINE: ABNORMAL OPERATION AND FAULT CONDITIONS;
ENVIRONMENTAL TESTS
SECTION TEN: CONSTRUCTIONAL REQUIREMENTS

60601-2-37 © IEC:2001(E) – 3 –

Annex AA (normative) Terminology – Index of defined terms .28

Annex BB (informative) Guidance and rationale for particular subclauses .30

Annex CC (informative) Guidance in classification according to CISPR 11.33

Annex DD (normative) Test methods for determining the MECHANICAL INDEX

and the THERMAL INDEX.34

Annex EE (informative) Relationships with other standards.39

Annex FF (informative) Guidance notes for measurement of OUTPUT POWER

in SCANNING MODE .40

Annex GG (informative) Rationale and derivation of index models .44
Annex HH (informative) Guidance on the interpretation of TI and MI to be used
to inform the OPERATOR.58
Bibliography.61
Figure FF.1 – Suggested 1 cm-wide aperture mask .42
Figure FF.2 – Suggested orientation of probe, mask slit, and RFB target .42
Figure FF.3 – Suggested orientation of probe, mask slit, and 1 cm RFB target.42
Figure GG.2a – Focused transducer with a large aperture .56
Figure GG.2b – Focused transducer with smaller aperture (≥1 cm ) .56
Figure GG.2c – Focused transducer with a weak focus (A > 1 cm ) .57
eq
Figure GG.2d – Weakly focused transducer .57
Table 101 – Acoustic output reporting table .21
Table DD.1 – Summary of combination formulae for each
of the THERMAL INDEX categories.38
Table DD.2 – Summary of the acoustic quantities required for the determination
of the indices .38
Table GG.1 – THERMAL INDEX categories and models .46
Table GG.2 – THERMAL INDEX formulae.50
Table HH.1 – Relative importance of maintaining low exposure indices
in various scanning situations .59

– 4 – 60601-2-37  IEC:2001(E)

INTERNATIONAL ELECTROTECHNICAL COMMISSION

____________
MEDICAL ELECTRICAL EQUIPMENT –

Part 2-37: Particular requirements for the safety

of ultrasonic diagnostic and monitoring equipment

FOREWORD
1) The IEC (International Electrotechnical Commission) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of the 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, the IEC publishes International Standards. Their preparation is
entrusted to technical committees; any IEC National Committee interested in the subject dealt with may
participate in this preparatory work. International, governmental and non-governmental organizations liaising
with the IEC also participate in this preparation. The IEC collaborates closely with the International
Organization for Standardization (ISO) in accordance with conditions determined by agreement between the
two organizations.
2) The formal decisions or agreements of the 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 National Committees.
3) The documents produced have the form of recommendations for international use and are published in the form
of standards, technical specifications, technical reports or guides and they are accepted by the National
Committees in that sense.
4) In order to promote international unification, IEC National Committees undertake to apply IEC International
Standards transparently to the maximum extent possible in their national and regional standards. Any
divergence between the IEC Standard and the corresponding national or regional standard shall be clearly
indicated in the latter.
5) The IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with one of its standards.
6) Attention is drawn to the possibility that some of the elements of this International Standard may be the subject
of patent rights. The IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 60601-2-37 has been prepared by subcommittee 62B: Diagnostic
imaging equipment, of IEC technical committee 62: Electrical equipment in medical practice.
The text of this standard is based on the following documents:
FDIS Report on voting
62B/428/FDIS 62B/440/RVD
Full information on the voting for the approval of this 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 3.
Annexes AA and DD form an integral part of this Particular Standard.
Annexes BB, CC, EE, FF, GG and HH are for information only.

60601-2-37 © IEC:2001(E) – 5 –

In this Particular Standard, the following print types are used:

– requirements, compliance with which can be tested, and definitions: in roman type

– notes, explanations, advice, introductions, general statements, exceptions, and references: in smaller type

– test specifications: in italic type

– TERMS USED THROUGHOUT THIS PARTICULAR STANDARD WHICH HAVE BEEN DEFINED IN CLAUSE 2

AND IEC 60601-1: IN SMALL CAPITALS.

The committee has decided that the contents of this publication will remain unchanged until 2002.
At this date, the publication will be

• reconfirmed;
• withdrawn;
• replaced by a revised edition, or
• amended.
A bilingual version of this standard may be issued at a later date.

– 6 – 60601-2-37  IEC:2001(E)

INTRODUCTION
In this Particular Standard, safety requirements additional to those in the General Standard

are specified for ULTRASONIC DIAGNOSTIC EQUIPMENT.

Guidance and a rationale for the requirements of this Particular Standard are given below.

Knowledge of the reasons for these requirements will not only facilitate the proper application
of this Particular Standard but will, in due course, expedite any revision necessitated by

changes in clinical practice or as a result of developments in technology.

General guidance and rationale
The approach and philosophy used in drafting this particular standard for safety of
ULTRASONIC DIAGNOSTIC EQUIPMENT are consistent with those in current standards in the
IEC 60601-2 series that apply to other diagnostic modalities, such as X-ray equipment and
magnetic resonance systems.
In each case, the safety standard is intended to require increasing sophistication of output
display indicators and/or controls with increasing energy levels in the interrogating field of
diagnosis. Thus, for all such diagnostic modalities, it is the responsibility of the OPERATOR to
understand the risk of the output of the equipment, and to act appropriately in order to obtain
the needed diagnostic information with the minimum risk to the PATIENT.
The reference given in the bibliography, UD-3 Rev.1, 1998: Standard for real-time display of
thermal and mechanical acoustic output indices on diagnostic ultrasound equipment will be
replaced by an IEC standard when available.
It should be noted that although UD-3 Rev.1, 1998 was developed as a national standard, it
has since been referenced by about 24 countries world wide and by all internationally
operating manufacturers and test houses; regulative authorities also follow the standard as it
has become a de facto international standard. The material taken from UD-3 Rev.1, 1998
forms only a part of this Particular Standard and is used to generate the present International
Standard which will be replaced by a revised edition within one year.
The standards currently under development, IEC 61973 and IEC 61681-1, will be considered
at the time of revision of this standard.
NOTE The ALARA principle, referred to in UD-3 Rev.1, 1998, is currently under discussion. This may be reflected
in the next edition of this Particular Standard.

60601-2-37 © IEC:2001(E) – 7 –

MEDICAL ELECTRICAL EQUIPMENT –

Part 2-37: Particular requirements for the safety

of ultrasonic medical diagnostic and monitoring equipment

SECTION ONE: GENERAL
The clauses and subclauses of this section of the General Standard apply except as follows:

1 Scope and object
This clause of the General Standard applies except as follows:
*1.1 Scope
Addition:
This Particular Standard specifies particular safety requirements for ULTRASONIC DIAGNOSTIC
EQUIPMENT as defined in 2.1.145.
This standard does not cover ultrasonic therapeutic equipment; however, equipment used for
the imaging of body structures by ultrasound in conjunction with therapeutic modalities is
covered.
1.2 Object
Replacement:
The object of this Particular Standard is to establish particular requirements for the safety of
ULTRASONIC DIAGNOSTIC EQUIPMENT and those aspects thereof which are directly related to
safety.
1.3 Particular Standards
Addition:
This Particular Standard amends and supplements a set of IEC publications, hereinafter

referred to as the “General Standard”, consisting of
IEC 60601-1:1988, Medical electrical equipment – Part 1: General requirements for safety and
its Amendments 1 (1991) and 2 (1995)
IEC 60601-1-2:1993, Medical electrical equipment – Part 1: General requirements for safety –
2. Collateral Standard: Electromagnetic compatibility – Requirements and tests
IEC 60601-1-4:1996, Medical electrical equipment – Part 1-4: General requirements for
safety – 4. Collateral Standard: Programmable electrical medical systems and its Amendment 1
(1999)
The numbering of sections, clauses and subclauses of this Particular Standard corresponds to
that of the General Standard. The changes to the text of the General Standard are specified
by the use of the following words:

– 8 – 60601-2-37  IEC:2001(E)

“Replacement” means that the clause or subclause of the General 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.
“Amendment” means that the clause or subclause of the General Standard is amended as
indicated by the text of this Particular Standard.

Subclauses or figures which are additional to those of the General Standard are numbered
starting from 101, additional annexes are lettered AA, BB, etc., and additional items aa), bb), etc.

Clauses and subclauses to which there is a rationale are marked with an asterisk (*). These
rationales can be found in an informative annex BB. Annex BB should be used in determining
the relevance of the requirements addressed, but should never be used to establish additional
test requirements.
Where there is no corresponding section, clause or subclause in this Particular Standard, the
section, clause or subclause of the General Standard applies without modification.
Where it is intended that any part of the General Standard, although possibly relevant, is not
to be applied, a statement to that effect is given in this Particular Standard.
A requirement of this Particular Standard replacing or modifying requirements of the General
Standard or of a Collateral Standard takes precedence over the corresponding general
requirement(s).
1.3.101 Related international standards
IEC 60529:1989, Degrees of protection provided by enclosures (IP Code)
IEC 60788:1984, Medical radiology – Terminology
IEC 61102:1991, Measurement and characterisation of ultrasonic fields using hydrophones in
the frequency range 0,5 MHz to 15 MHz
IEC 61157:1992, Requirements for the declaration of the acoustic output of medical
diagnostic ultrasonic equipment
IEC 61161:1992, Ultrasonic power measurement in liquids in the frequency range 0,5 MHz to
25 MHz
Amendment 1 (1998)
2 Terminology and definitions
This clause of the General Standard applies except as follows:
Additional definitions:
2.1.101
ACOUSTIC ATTENUATION COEFFICIENT
coefficient intended to account for ultrasonic attenuation of tissue between the source and a
specified point
Symbol: α
–1 –1
Unit: decibels per centimetre per megahertz, dB cm MHz

60601-2-37 © IEC:2001(E) – 9 –

2.1.102
ACOUSTIC WORKING FREQUENCY
arithmetic mean of the most widely separated frequencies f and f at which the amplitude of
1 2
the pressure spectrum of the acoustic signal is 3 dB lower than the peak amplitude

[3.4.2 of IEC 61102, modified]

Symbol: f
awf
Unit: megahertz, MHz
2.1.103
ATTENUATED OUTPUT POWER
value of the acoustic OUTPUT POWER after attenuation and at a specified distance from the
transducer, and given by
(-α z f /10)
awf
P = P 10
α
where
α is the ACOUSTIC ATTENUATION COEFFICIENT in decibels per centimetre per megahertz;
z is the distance from the source to the point of interest in centimetres;
f is the ACOUSTIC WORKING FREQUENCY in megahertz;
awf
P is the ATTENUATED OUTPUT POWER in milliwatts;
α
P is the OUTPUT POWER in milliwatts measured in water.
Symbol: P
α
Unit: milliwatts, mW
2.1.104
ATTENUATED PEAK-RAREFACTIONAL ACOUSTIC PRESSURE
value of the PEAK-RAREFACTIONAL ACOUSTIC PRESSURE after attenuation and at a specified
point, and given by
(-α z f /20)
awf
p (z) = p (z) 10
ra r
where
α is the ACOUSTIC ATTENUATION COEFFICIENT in decibels per centimetre per megahertz;
z is the distance from the source to the point of interest, in centimetres;
f is the ACOUSTIC WORKING FREQUENCY in megahertz;
awf
p (z) is the PEAK-RAREFACTIONAL ACOUSTIC PRESSURE measured in water.
r
Symbol: p
ra
Unit: megapascals, MPa
– 10 – 60601-2-37  IEC:2001(E)

2.1.105
ATTENUATED PULSE-AVERAGE INTENSITY

value of the acoustic PULSE-AVERAGE INTENSITY after attenuation and at a specified point, and

given by
( -α z f /10)
awf
=
I I (z) 10
pa,α pa
where
α is the ACOUSTIC ATTENUATION COEFFICIENT in decibels per centimetre per megahertz;

z is the distance from the source to the point of interest in centimetres;
f is the ACOUSTIC WORKING FREQUENCY, at distance z in megahertz;
awf
I (z) is the PULSE-AVERAGE INTENSITY measured in water, in milliwatts per centimetre
pa
squared.
Symbol: I
pa,α
–2
Unit: watts per centimetre squared, W cm
2.1.106
ATTENUATED PULSE-INTENSITY INTEGRAL
value of the PULSE-INTENSITY INTEGRAL after attenuation and at a specified point, and given by
α
(- z f /10)
awf
I = I 10
pi,α pi
where
α is the ACOUSTIC ATTENUATION COEFFICIENT in decibels per centimetre per megahertz;
z is the distance from the source to the point of interest in centimetres;
f is the ACOUSTIC WORKING FREQUENCY in megahertz;
awf
I is the ATTENUATED PULSE-INTENSITY INTEGRAL in millijoules per centimetre squared;
pi,α
measured in water in millijoules per centimetre
I is the PULSE-INTENSITY INTEGRAL
pi
squared.
Symbol: I
pi,α
–2
Unit: millijoules per centimetre squared, mJ cm
2.1.107
ATTENUATED SPATIAL-PEAK TEMPORAL-AVERAGE INTENSITY
value of the SPATIAL-PEAK TEMPORAL AVERAGE INTENSITY after attenuation and at a specified

distance z, and given by
(-α z f /10)
awf
I (z) = I (z) 10
zpta,α zpta
where
α is the ACOUSTIC ATTENUATION COEFFICIENT in decibels per centimetre per megahertz;
z is the distance from the source to the point of interest in centimetres;
f is the ACOUSTIC WORKING FREQUENCY in megahertz;
awf
I (z) is the SPATIAL-PEAK TEMPORAL-AVERAGE INTENSITY, at a specified distance z in milliwatts
zpta
per centimetre squared measured in water.
Symbol: I (z)
zpta,α
–2
Unit: milliwatts per centimetre squared, mW cm

60601-2-37 © IEC:2001(E) – 11 –

2.1.108
ATTENUATED TEMPORAL-AVERAGE INTENSITY

value of the TEMPORAL-AVERAGE INTENSITY after attenuation and at a specified point, and given by

( -α z f /10)
awf
I (z) = I (z) 10
ta,α ta
where
α is the
ACOUSTIC ATTENUATION COEFFICIENT in decibels per centimetre per megahertz;

z is the distance from the source to the point of interest in centimetres;

f is the ACOUSTIC WORKING FREQUENCY in megahertz;
awf
I (z) is the ATTENUATED TEMPORAL-AVERAGE INTENSITY in milliwatts per centimetre squared;
ta,α
I (z)is the TEMPORAL-AVERAGE INTENSITY measured in water in milliwatts per centimetre
ta
squared.
Symbol: I (z)
ta,α
–2
Unit: milliwatts per centimetre squared, mW cm
2.1.109
BEAM AREA
area in a specified plane perpendicular to the BEAM-ALIGNMENT AXIS consisting of all points at
which the PULSE-INTENSITY INTEGRAL is greater than a specified fraction of the maximum
PULSE-INTENSITY INTEGRAL in that plane
[3.6 of IEC 61102, modified]
NOTE For measurement purposes the PULSE INTENSITY INTEGRAL can be taken as being proportional to the PULSE
PRESSURE-SQUARED INTEGRAL
2.1.110
BEAM ALIGNMENT AXIS
straight line joining the points of maximum PULSE INTENSITY INTEGRAL measured at several
different distances in the far field. For the purposes of alignment, this line may be projected to
the face of the ULTRASONIC TRANSDUCER
[3.5 of IEC 61102, modified]
2.1.111
BONE THERMAL INDEX
THERMAL INDEX for applications, such as foetal (second and third trimester) or neonatal
cephalic (through the fontanelle), in which the ultrasound beam passes through soft tissue
and a focal region is in the immediate vicinity of bone
Symbol: TIB
Unit: None
NOTE See annex DD.4.2 and DD.5.2 for methods of determining the BONE THERMAL INDEX.
2.1.112
BOUNDED OUTPUT POWER
OUTPUT POWER emitted in SCANNING MODE from a region of the active area of the transducer
whose width in the scan plane is limited to 1 cm
Symbol: P
Unit: milliwatts, mW
– 12 – 60601-2-37  IEC:2001(E)

2.1.113
BREAK-POINT DEPTH
value equal to 1,5 times the EQUIVALENT APERTURE DIAMETER, and given by

z = 1,5 D
bp eq
where
D is the EQUIVALENT APERTURE DIAMETER.

eq
Symbol: z
bp
Unit: centimetres, cm
2.1.114
COMBINED-OPERATING MODE
mode of operation of an EQUIPMENT which combines more than one DISCRETE-OPERATING MODE
[3.6 of IEC 61157]
2.1.115
CRANIAL-BONE THERMAL INDEX
THERMAL INDEX for applications, such as paediatric and adult cranial applications, in which the
ultrasound beam passes through bone near the beam entrance into the body
Symbol: TIC
Unit: None
NOTE See annex DD.4.3 for methods of determining the CRANIAL BONE THERMAL INDEX.
2.1.116
DEFAULT SETTING
specific state of control, the ULTRASONIC DIAGNOSTIC EQUIPMENT will enter upon power-up, new
PATIENT select or change from non-foetal to foetal applications
2.1.117
DEPTH FOR BONE THERMAL INDEX
distance from the plane where the –12 dB OUTPUT BEAM DIMENSIONS are determined along the
BEAM ALIGNMENT AXIS to the plane where the product of ATTENUATED OUTPUT POWER and
ATTENUATED PULSE-INTENSITY INTEGRAL is maximum
Symbol: z
b
Unit: centimetres, cm
2.1.118
DEPTH FOR SOFT-TISSUE THERMAL INDEX
distance from the plane where the –12 dB OUTPUT BEAM DIMENSIONS are determined along the
BEAM ALIGNMENT AXIS to the plane at which the lower value of the ATTENUATED OUTPUT POWER
and the product of the ATTENUATED SPATIAL-PEAK TEMPORAL-AVERAGE INTENSITY and 1 cm is
maximized over the distance range equal to, or more than, 1,5 times the EQUIVALENT
APERTURE DIAMETER
Symbol: z
s
Unit: centimetres, cm
NOTE In this Particular Standard, the restricted definition of SPATIAL-PEAK TEMPORAL-AVERAGE INTENSITY from 3.49
of IEC 61102 relating to a specified plane is used where SPATIAL-PEAK TEMPORAL-AVERAGE INTENSITY is replaced by
ATTENUATED SPATIAL-PEAK TEMPORAL-AVERAGE INTENSITY.

60601-2-37 © IEC:2001(E) – 13 –

2.1.119
DISCRETE-OPERATING MODE
mode of operation of ULTRASONIC DIAGNOSTIC EQUIPMENT in which the purpose of the excitation

of the ULTRASONIC TRANSDUCER or ULTRASONIC TRANSDUCER element group is to utilize only

one diagnostic methodology
[3.7 of IEC 61157]
2.1.120
EQUIVALENT APERTURE DIAMETER
diameter of a circle whose area is the –12 dB OUTPUT BEAM AREA and given by

D ≡ A
eq aprt
π
where
A
is the –12 dB OUTPUT BEAM AREA.
aprt
Symbol: D
eq
Unit: centimetres, cm
NOTE This formula gives the diameter of a circle whose area is the –12 dB OUTPUT BEAM AREA. It is used in the
calculation of the CRANIAL-BONE THERMAL INDEX and the SOFT TISSUE THERMAL INDEX.
2.1.121
EQUIVALENT BEAM AREA
value of the area of the acoustic beam at the distance z in terms of power and intensity, and given by
P
P
α
A (z) ≡ =
eq
I (z) I (z)
zpta,α zpta
where
P
(z) is the ATTENUATED OUTPUT POWER, at the distance z, in milliwatts;
α
I (z)is the ATTENUATED SPATIAL-PEAK TEMPORAL-AVERAGE INTENSITY, at the distance z,
zpta,α
in milliwatts per square centimetre;
P is the OUTPUT POWER in milliwatts;
I (z) is the SPATIAL-PEAK TEMPORAL-AVERAGE INTENSITY, at the distance z, in milliwatts per
zpta
square centimetre; and
z is the distance from the source to the specified point in centimetres.
Symbol: A (z)
eq
Unit: centimetres squared, cm
2.1.122
EQUIVALENT BEAM DIAMETER
value of the diameter of the acoustic beam at the distance z in terms of the EQUIVALENT BEAM
AREA, and given by
d (z) = A (z)
eq eq
π
where
A (z) is the EQUIVALENT BEAM AREA;
eq
z is the distance from the source to the specified point.
Symbol: d (z)
eq
Unit: centimetres, cm
– 14 – 60601-2-37  IEC:2001(E)

2.1.123
FULL SOFTWARE CONTROL OF ACOUSTIC OUTPUT

means by which the EQUIPMENT establishes values of the acoustic output quantities

independent of direct OPERATOR control

2.1.124
MECHANICAL INDEX
MECHANICAL INDEX is given by
−1/2
p f
ra awf
MI ≡
C
MI
where
–1/2
C = 1 MPa MHz ;
MI
p is the ATTENUATED PEAK-RAREFACTION PRESSURE in megapascals;
ra
f is the ACOUSTIC WORKING FREQUENCY in megahertz.
awf
Symbol: MI
Unit: None
2.1.125
MULTI-PURPOSE ULTRASONIC EQUIPMENT
ultrasonic equipment which is intended for more than one clinical application
2.1.126
NON-SCANNING MODE
mode of operation of ULTRASONIC DIAGNOSTIC EQUIPMENT that involves a sequence of
ultrasonic pulses which give rise to ultrasonic scan lines that follow the same acoustic path
[3.12 of IEC 61157, modified]
2.1.127
–12 dB OUTPUT BEAM AREA
area of the ultrasonic beam derived from the –12 dB OUTPUT BEAM DIMENSIONS
[3.13 of IEC 61157, modified]
Symbol: A
aprt
Unit: centimetre squared, cm
2.1.128
–12 dB OUTPUT BEAM DIMENSIONS
dimensions of the ultrasonic beam (–12 dB PULSE BEAM WIDTH) in specified directions normal
to the BEAM ALIGNMENT AXIS and at the transducer output face
[3.14 of IEC 61157, modified]
NOTE 1 For reasons of measurement accuracy the –12 dB OUTPUT BEAM DIMENSIONS can be derived from
measurements at a distance chosen to be as close as possible to the face of the transducer, and if possible no
more than 1 mm from the face (3.14 of IEC 61157, modified).
NOTE 2 For contact transducers, these dimensions can be taken as the dimensions of the radiating element.
Symbol: X, Y
Unit: centimetres, cm
60601-2-37 © IEC:2001(E) – 15 –

2.1.129
OUTPUT POWER
time-average power radiated by an ULTRASONIC TRANSDUCER into an approximately free field under

specified conditions in a specified medium, preferably water

[3.5 of IEC 61161, modified]
Symbol: P
Unit: milliwatts, mW
2.1.130
PEAK-RAREFACTIONAL ACOUSTIC PRESSURE

maximum of the modulus of the negative instantaneous acoustic pressure in an acoustic field
during an acoustic repetition period
[3.34 of IEC 61157, modified]
Symbol: p
r
Unit: megapascals, MPa
2.1.131
PRUDENT-USE STATEMENT
affirmation of the principle advising avoidance of primarily high exposure levels and
secondarily long exposure times while acquiring necessary clinical information
2.1.132
PULSE-AVERAGE INTENSITY
ratio of the PULSE INTENSITY INTEGRAL I to the PULSE DURATION t
pi d
Symbol: I
pa
–2
Unit: watts per square centimetre, W cm
2.1.133
PULSE BEAM-WIDTH
distance between two points, on a specified surface in a specified direction passing through the
point of maximum PULSE-PRESSURE-SQUARED INTEGRAL (p) in that surface, at which the PULSE-
i
PRESSURE-SQUARED INTEGRAL is a specified fraction of the maximum value in that surface
[3.18 of IEC 61157, modified]
Symbol: d (for PULSE BEAM-WIDTH defined at –6dB)
–6
Unit: centimetres, cm
2.1.134
PULSE DURATION
1,25 times the interval between the time when the time integral of intensity in an acoustic
pulse at a point reaches 10 % and when it reaches 90 % of the PULSE INTENSITY INTEGRAL
[3.30 of IEC 61102, modified]
Symbol: t
d
Unit: seconds, s
2.1.135
PULSE-INTENSITY INTEGRAL
time integral of the instantaneous intensity at a particular point in an acoustic field integrated
over the acoustic pulse waveform
[3.31 of IEC 61102]
Symbol: I
pi
–2
Unit: millijoules per centimetre squared, mJ cm

– 16 – 60601-2-37  IEC:2001(E)

2.1.136
PULSE-PRESSURE-SQUARED INTEGRAL

time integral of the square of the instantaneous acoustic pressure at a particular point in an

acoustic field integrated over the acoustic pulse waveform

[3.33 of IEC 61102]
Symbol: p
i
Unit: Pascal squared seconds, Pa s

2.1.137
PULSE REPETITION RATE
inverse of the time interval between two successive acoustic pulses
[3.35 of IEC 61102, modified]
Symbol: prr
Unit: hertz, Hz
2.1.138
SCANNING MODE
mode of operation of an ULTRASONIC DIAGNOSTIC EQUIPMENT that involves a sequence of
ultrasonic pulses which give rise to scan lines that do not follow the same acoustic path
[3.21 of IEC 61157, modified]
2.1.139
SOFT TISSUE THERMAL INDEX
THERMAL INDEX related to soft tissues
Symbol: TIS
Unit: None
NOTE 1 See annex DD.5.1 and the following for methods of determination of the SOFT-TISSUE THERMAL INDEX.
NOTE 2 For the purposes of this document, soft tissue includes all body tissues and fluids but excludes skeletal
tissues
2.1.140
SPATIAL-PEAK TEMPORAL-AVERAGE INTENSITY
maximum value of the TEMPORAL-AVERAGE INTENSITY in a specified plane at a specified
distance z from the transducer
[3.49 of IEC 61102, modified]
Symbol: I (z)
zpta
–2
Unit: milliwatts per centimetre squared, mW cm
NOTE In this standard the restricted definition from 3.49 of IEC 61102 relating to a specified plane is used.
2.1.141
TEMPORAL-AVERAGE INTENSITY
time-average of the instantaneous intensity at a particular point in an acoustic field
[3.53 of IEC 61102, modified]
Symbol: I
(z)
ta
–2
Unit: milliwatts per centimetre squared, mW cm

60601-2-37 © IEC:2001(E) – 17 –

2.1.142
THERMAL INDEX
ratio of attenuated acoustic power at a specified point to the attenuated acoustic power

required to raise the temperature at that point in a specific tissue model by 1 °C

Symbol: TI
Unit: None
2.1.143
TRANSDUCER ASSEMBLY
transducer housing (probe), any associated electronic circuitry and any liquids contained in the

housing and the integral cable which connects the transducer probe to an ultrasound console
[see 3.22 of IEC 61157]
2.1.144
TRANSMIT PATTERN
combination of a specific set of transducer beam-forming characteristics (determined by the
transmit aperture size, apodization shape and relative timing/phase delay pattern across the
aperture, resulting in a specific focal length and direction), and an electrical drive waveform of
a specific fixed shape but variable amplitude
2.1.145
ULTRASONIC DIAGNOSTIC EQUIPMENT
MEDICAL ELECTRICAL EQUIPMENT which is intended for in vivo ultrasonic and monitoring
examination for obtaining a medical diagnosis
NOTE See also definition 3.11 of IEC 61157: medical diagnostic ultrasonic equipment (or system) – combination
of the ultrasound instrument console and the TRANSDUCER ASSEMBLY making up a complete diagnostic system.
2.1.146
ULTRASONIC TRANSDUCER
device capable of converting electrical energy to mechanical energy and/or mechanical
energy to electrical energy, both within the ultrasonic frequency range

– 18 – 60601-2-37  IEC:2001(E)

2.101 List of symbols
ACOUSTIC ATTENUATION COEFFICIENT
α
A
–12dB OUTPUT BEAM AREA
aprt
C NORMALIZING COEFFICIENT
MI
D
EQUIVALENT APERTURE DIAMETER
eq
d PULSE BEAM WIDTH
–6
d
EQUIVALENT BEAM DIAMETER
eq
f ACOUSTIC WORKING FREQUENCY
awf
I
PULSE-AVERAGE INTENSITY
pa
I ATTENUATED PULSE-AVERAGE INTENSITY
pa,α
I
PULSE-INTENSITY INTEGRAL
pi
I ATTENUATED PULSE-INTENSITY INTEGRAL
pi,α
I (z)
TEMPORAL-AVERAGE INTENSITY
ta
I (z) ATTENUATED TEMPORAL-AVERAGE INTENSITY
ta,α
I (z) SPATIAL-PEAK TEMPORAL-AVERAGE INTENSITY
zpta
I (z) ATTENUATED SPATIAL-PEAK TEMPORAL-AVERAGE INTENSITY
zpta,α
MI MECHANICAL INDEX
P OUTPUT POWER
P ATTENUATED OUTPUT POWER
α
P BOUNDED OUTPUT POWER
p PULSE PRESSURE SQUARED INTEGRAL
i
p PEAK-RAREFACTIONAL ACOUSTIC PRESSURE
r
p ATTENUATED PEAK-RAREFACTIONAL ACOUSTIC PRESSURE
ra
prr PULSE REPETITION RATE
TI THERMAL INDEX
TIB BONE THERMAL INDEX
TIC CRANIAL-BONE THERMAL INDEX
TIS SOFT-TISSUE THERMAL INDEX
t PULSE DURATION
d
X, Y –12 dB OUTPUT BEAM DIMENSIONS

z DISTANCE FROM THE SOURCE TO A SPECIFIED POINT
z DEPTH FOR TIB
b
z BREAK-POINT DEPTH
bp
z DEPTH FOR TIS
s
60601-2-37 © IEC:2001(E) – 19 –

6 Identification, marking and documents

This clause of the General Standard applies except as follows:

6.1 Marking on the outside of EQUIPMENT or EQUIPMENT parts

Addition:
aa) Compliance with EMC requirements

Intra-corporal TRANSDUCER ASSEMBLIES that do not comply with the electromagnetic

compliance requirements of clause 36 shall have applied the following IEC symbol to the
TRANSDUCER ASSEMBLY: symbol 14 of table DI in annex D of the General Standard.
Replacement:
*p) Output
For ULTRASONIC DIAGNOSTIC EQUIPMENT capable of generating output levels subject to 51.2
bb), cc) or dd), and which allows the OPERATOR to directly vary the output levels, the
action needed to increase or decrease the output levels shall be clear to the OPERATOR.
This marking shall be of the nature of an active DISPLAY.
Replacement:
q) Physiological effects, symbols and warning statements
MULTI-PURPOSE ULTRASONIC EQUIPMENT capable of ultrasound output levels subject to 51.2
bb) or dd) should carry the marking described as symbol 14 in table DI of annex D of the
General Standard, affixed to the CONTROL PANEL or other readily visible location. The
purpose of this marking is to alert the OPERATOR to consult the INSTRUCTIONS FOR USE
before operation of the ULTRASONIC DIAGNOSTIC EQUIPMENT.
6.3 Marking of controls and instruments
Additional items:
aa) A display of THERMAL INDEX and MECHANICAL INDEX shall be provided in accordance with
the requirements of 51.2, together with the declaration of accuracy described in 6.8.2
and 50.2.
bb) A display of the surface temperature of ULTRASONIC TRANSDUCERS intended for trans-
oesophageal use shall be provided in accordance with 42.3, 50.2, and 51.2.
cc) A display relevant to ultrasound output levels (see 51.2) shall be clearly visible from the
OPERATOR’S position, with the full name(s) or abbreviation(s) of the index (indices)
displayed.
6.8.2 INSTRUCTIONS FOR USE
Additional items:
aa) INSTRUCTIONS FOR USE shall contain the following:
1) the procedures necessary for safe operation, drawing attention to the safety hazards
which may occur as a result of an inadequate electrical installation when the APPLIED
PART of the ULTRASONIC DIAGNOSTIC EQUIPMENT is of TYPE B;
2) the type of electrical installation to which the ULTRASONIC DIAGNOSTIC EQUIPMENT may
be safely connected, including the connection of any POTENTIAL EQUALIZATION
CONDUCTOR;
– 20 – 60601-2-37  IEC:2001(E)

3) the safe use of internal and external TRANSDUCER ASSEMBLIES, and in particular that

the ULTRASONIC DIAGNOSTIC EQUIPMENT is of the correct type for its intended applic-

ation; for TRANSDUCER ASSEMBLIES intended for intra-corporeal use, a warning in the

instructions not to activate the TRANSDUCER ASSEMBLY outside the PATIENT’s body if

the TRANSDUCER ASSEMBLY, when so activated, would not comply with

electromagnetic compliance requirements and may cause harmful interference with

other equipment in the environment. The identification of interference with other
equipment and mitigation techniques shall be included in the INSTRUCTIONS FOR USE if

a reduction in test levels is claimed by the MANUFACTURER;

4) a description of those parts of the TRANSDUCER ASSEMBLY which may be immersed in

water or other liquids either for NORMAL USE or performance assessment purposes;

5) a notice if the ULTRASONIC DIAGNOSTIC EQUIPMENT or parts thereof are provided with
protective means against burns to the PATIENT when used with HF surgical
equipment. If no such means are incorporated, notice shall be given in the
ACCOMPANYING DOCUMENTS and advice shall be given regarding the location and use
of the TRANSDUCER ASSEMBLY to reduce the hazard of burns in the event of a defect in
the HF surgical neutral electrode connection;
6) a recommendation calling the USER’S attention to the need for regular testing and
periodic maintenance, and especially
– inspection of the TRANSDUCER ASSEMBLY for cracks which allow the ingress of
conductive fluid;
– inspection of the TRANSDUCER ASSEMBLY cables and associated connectors;
7) the appropriate use of the ULTRASONIC DIAGNOSTIC EQUIPMENT to avoid mechanical
damage to the TRANSDUCER ASSEMBLY;
8) for MULTI-PURPOSE ULTRASONIC DIAGNOSTIC EQUIPMENT capable of ultrasound output
levels significantly greater than those typically used for certain intended applications
of the ULTRASONIC DIAGNOSTIC EQUIPMENT, instructions regarding the avoidance of
unintended acoustic output control settings and levels;
9) a PRUDENT-USE STATEMENT for ULTRASONIC DIAGNOSTIC EQUIPMENT capable of gener-
ating output levels subject to 51.2 bb), cc) or dd);
10) in a separate section descriptions of any DISPLAY or means by which the OPERATOR
may modify the operation of the EQUIPMENT relevant to ultrasound output (see 8) and
9) above, and 6.8.3);
11) description of any DISPLAY or means by which the OPERATOR may modify the
operation of the EQUIPMENT relevant to surface temperature for ULTRASONIC
TRANSDUCERS intended for trans-oesophageal use;
12) if the surface temperature of the TRANSDUCER ASSEMBLY can exceed 41 °C, the
maximum temperature shall be disclosed.
13) for ULTRASONIC DIAGNOSTIC EQUIPMENT capable of generating output levels subject to

51.2 bb), cc) or dd), information to the USER on how to interpret the displayed
ultrasonic exposure parameters, THERMAL INDEX (TI) and MECHANICAL INDEX (MI)
according to the guidance given in annex HH.
6.8.3 Technical description
Additional item:
aa) Technical data regarding acoustic output levels to be required in the OPERATOR’S manual.
For each mode, provide the maximum value of each index (as well as the associated
parameters listed for the operating condition resulting in the maximum index value), for
which the operating mode in question is the largest (or sole) contributor.

60601-2-37 © IEC:2001(E) – 21 –

Table 101 – Acoustic output reporting table

TIS TIB
Index label MI Non-scan TIC
Non-
Scan
scan
2 2
A ≤≤≤≤ 1 cm A > 1 cm
aprt aprt
Maximum index value X X X X X X

p X
ra
P
XX X X
Min. of [P (z ), I (z )] X
α s ta,α s
z X
s
z
X
bp
Associated
acoustic z X
b
parameters
z at max. I X
pi,α
d (z ) X
eq b
f XX X X XX
awf
Dim of A XX X X X X
aprt
YX X X X X
t
X
d
prr X
Other
p at max. I X
r pi
information
d at max. I X
eq pi
I at max. MI X
pa,α
Control 1 X X X X X X
Operating
Control 2 X X X X X X
control
Control 3 X X X X X X
conditions
NOTE 1 Information need not be provided for any formulation of TIS not yielding the maximum value of TIS
for that mode.
NOTE 2 Information need not be provided regarding TIC for any TRANSDUCER ASSEMBLY not intended for
transcranial or neonatal cephalic uses.
NOTE 3 Information on MI and TI need not be provided if the equipment meets both exemption clauses
given in 51.2 aa) and 51.2 dd).

SECTION TWO: ENVIRONMENTAL CONDITIONS
The clauses and subclauses of this section of the General Standard apply.
SECTION THREE: PROTECTION AGAINST ELECTRIC SHOCK HAZARDS
The clauses and subclauses of this section of the General Standard apply except as follows:
19 Continuous LEAKAGE CURRENTS and PATIENT AUXILIARY CURRENTS
Addition:
19.4 g)5) For testing the TRANSDUCER ASSEMBLIES a saline solution in which the APPLIED PART
is immersed shall be used.
– 22 – 60601-2-37  IEC:2001(E)

Addition:
19.4 h)9) For testing the TRANSDUCER ASSEMBLIES a saline solution in which the APPLIED PART
is immersed shall be used.
20 Dielectric strength
Addition:
20.4 h) For testing the TRANSDUCER ASSEMBLIES a saline solution in which the APPLIED PART is

immersed shall be used.
SECTION FOUR: PROTECTION AGAINST MECHANICAL HAZARDS
The clauses and subclauses of this section of the General Standard apply.
SECTION FIVE: PROTECTION AGAINST HAZARDS FROM UNWANTED
OR EXCESSIVE RADIATION
The
...

INTERNATIONAL IEC
STANDARD 60601-2-37
Edition 1.1
2004-10
Edition 1:2001 consolidated with amendment 1:2004

Medical electrical equipment –

Part 2-37:
Particular requirements for the safety
of ultrasonic medical diagnostic
and monitoring equipment
Reference number
Publication numbering
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60000 series. For example, IEC 34-1 is now referred to as IEC 60034-1.

Consolidated editions
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edition numbers 1.0, 1.1 and 1.2 refer, respectively, to the base publication, the

base publication incorporating amendment 1 and the base publication incorporating

amendments 1 and 2.
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INTERNATIONAL IEC
STANDARD 60601-2-37
Edition 1.1
2004-10
Edition 1:2001 consolidated with amendment 1:2004

Medical electrical equipment –

Part 2-37:
Particular requirements for the safety
of ultrasonic medical diagnostic
and monitoring equipment
 IEC 2004  Copyright - all rights reserved
No part of this publication may be reproduced or utilized in any form or by any means, electronic or
mechanical, including photocopying and microfilm, without permission in writing from the publisher.
International Electrotechnical Commission, 3, rue de Varembé, PO Box 131, CH-1211 Geneva 20, Switzerland
Telephone: [phone] Telefax: [phone] E-mail: [e-mail] Web: www.iec.ch
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Commission Electrotechnique Internationale

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МеждународнаяЭлектротехническаяКомиссия
For price, see current catalogue

– 2 – 60601-2-37  IEC:2001+A1:2004(E)

CONTENTS
FOREWORD.4

INTRODUCTION.6

SECTION ONE: GENERAL
1 Scope and object .7

2 Terminology and definitions .8

3 General requirements .18
6 Identification, marking and documents .18

SECTION TWO: ENVIRONMENTAL CONDITIONS
SECTION THREE: PROTECTION AGAINST ELECTRIC SHOCK HAZARDS
19 Continuous LEAKAGE CURRENTS and PATIENT AUXILIARY CURRENTS .21
20 Dielectric strength.22

SECTION FOUR: PROTECTION AGAINST MECHANICAL HAZARDS
SECTION FIVE: PROTECTION AGAINST HAZARDS FROM UNWANTED
OR EXCESSIVE RADIATION
*35 Acoustical energy (including ultrasonic) .22
*36 Electromagnetic compatibility.22

SECTION SIX: PROTECTION AGAINST HAZARDS OF IGNITION
OF FLAMMABLE ANESTHETIC MIXTURES
SECTION SEVEN: PROTECTION AGAINST EXCESSIVE TEMPERATURES
AND OTHER SAFETY HAZARDS
42 Excessive temperatures.25
44 Overflow, spillage, leakage, humidity, ingress of liquids, cleaning, sterilization,
and disinfection .28

SECTION EIGHT: ACCURACY OF OPERATING DATA AND PROTECTION
AGAINST HAZARDOUS OUTPUT
50 Accuracy of operating data .28
51 Protection against hazardous output .29

SECTION NINE: ABNORMAL OPERATION AND FAULT CONDITIONS;
ENVIRONMENTAL TESTS
SECTION TEN: CONSTRUCTIONAL REQUIREMENTS

60601-2-37 © IEC:2001+A1:2004 (E) – 3 –

Annex AA (normative) Terminology – Index of defined terms .31

Annex BB (informative) Guidance and rationale for particular subclauses.33

Annex CC (informative) Guidance in classification according to CISPR 11.37

Annex DD (normative) Test methods for determining the MECHANICAL INDEX

and the THERMAL INDEX.38

Annex EE (informative) Relationships with other standards .43

Annex FF (informative) Guidance notes for measurement of OUTPUT POWER

in SCANNING MODE .44

Annex GG (informative) Rationale and derivation of index models .48

Annex HH (informative) Guidance on the interpretation of TI and MI to be used
to inform the OPERATOR.62
Annex II (informative) Example set-up to measure surface temperature
for externally applied transducers .65

Bibliography.68

Figure FF.1 – Suggested 1 cm-wide aperture mask .46
Figure FF.2 – Suggested orientation of probe, mask slit, and RFB target .46
Figure FF.3 – Suggested orientation of probe, mask slit, and 1 cm RFB target .46
Figure GG.2a – Focused transducer with a large aperture .60
Figure GG.2b – Focused transducer with smaller aperture (≥1 cm ) .60
Figure GG.2c – Focused transducer with a weak focus (A > 1 cm ) .61
eq
Figure GG.2d – Weakly focused transducer .61
Figure II.1 – Set-up of an example test object to measure the surface temperature
of externally applied transducers .67

Table 101 – Acoustic output reporting table .21
Table 102 – Overview of the tests noted under 42.3.27
Table DD.1 – Summary of combination formulae
for each of the THERMAL INDEX categories .42
Table DD.2 – Summary of the acoustic quantities required for the determination
of the indices .42
Table GG.1 – THERMAL INDEX categories and models .50

Table GG.2 – THERMAL INDEX formulae.54
Table HH.1 – Relative importance of maintaining low exposure indices
in various scanning situations .63
Table II.1 – Acoustic and thermal properties of tissues and materials .65
Table II.2 – Weight % pure components.66

– 4 – 60601-2-37 © IEC:2001+A1:2004(E)

INTERNATIONAL ELECTROTECHNICAL COMMISSION

____________
MEDICAL ELECTRICAL EQUIPMENT –

Part 2-37: Particular requirements for the safety

of ultrasonic medical diagnostic and monitoring equipment

FOREWORD
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International Standard IEC 60601-2-37 has been prepared by subcommittee 62B: Diagnostic
imaging equipment, of IEC technical committee 62: Electrical equipment in medical practice.
This consolidated version of IEC 60601-2-37 consists of the first edition (2001) [documents
62B/428/FDIS and 62B/440/RVD] and its amendment 1 (2004) [documents 62B/524/FDIS and
62B/542/RVD].
The technical content is therefore identical to the base edition and its amendment and has
been prepared for user convenience.
It bears the edition number 1.1.
A vertical line in the margin shows where the base publication has been modified by
amendment 1.
Annexes AA and DD form an integral part of this Particular Standard.
Annexes BB, CC, EE, FF, GG and HH are for information only.

60601-2-37 © IEC:2001+A1:2004 (E) – 5 –

In this Particular Standard, the following print types are used:

– requirements, compliance with which can be tested, and definitions: in roman type

– notes, explanations, advice, introductions, general statements, exceptions, and references: in smaller type

– test specifications: in italic type

TERMS USED THROUGHOUT THIS PARTICULAR STANDARD WHICH HAVE BEEN DEFINED IN CLAUSE 2
–
AND IEC 60601-1: IN SMALL CAPITALS.

The committee has decided that the contents of the base publication and its amendments will

remain unchanged until the maintenance result 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.
A bilingual version of this standard may be issued at a later date.

– 6 – 60601-2-37  IEC:2001+A1:2004(E)

INTRODUCTION
In this Particular Standard, safety requirements additional to those in the General Standard

are specified for ULTRASONIC DIAGNOSTIC EQUIPMENT.

Guidance and a rationale for the requirements of this Particular Standard are given below.

Knowledge of the reasons for these requirements will not only facilitate the proper application

of this Particular Standard but will, in due course, expedite any revision necessitated by

changes in clinical practice or as a result of developments in technology.

General guidance and rationale
The approach and philosophy used in drafting this particular standard for safety of
ULTRASONIC DIAGNOSTIC EQUIPMENT are consistent with those in current standards in the
IEC 60601-2 series that apply to other diagnostic modalities, such as X-ray equipment and
magnetic resonance systems.
In each case, the safety standard is intended to require increasing sophistication of output
display indicators and/or controls with increasing energy levels in the interrogating field of
diagnosis. Thus, for all such diagnostic modalities, it is the responsibility of the OPERATOR to
understand the risk of the output of the equipment, and to act appropriately in order to obtain
the needed diagnostic information with the minimum risk to the PATIENT.
It should be noted that although UD-3 Rev.1, 1998 was developed as a national standard, it
has since been referenced by numerous countries worldwide and by all internationally
operating manufacturers and test houses; regulatory authorities also follow the standard, as it
has become a de facto international standard. The material taken from UD-3 Rev.1, 1998
forms only a part of this Particular Standard.
This standard contains normative measurement methodologies. These clauses may be
replaced in a future revision by reference to an appropriate future measurement standard.
This standard does not cover ultrasonic therapeutic equipment. Equipment used for the
imaging and diagnosis of body structures by ultrasound in conjunction with other medical
procedure is covered.
________
See reference [19] in the Bibliography.

60601-2-37 © IEC:2001+A1:2004 (E) – 7 –

MEDICAL ELECTRICAL EQUIPMENT –

Part 2-37: Particular requirements for the safety

of ultrasonic medical diagnostic and monitoring equipment

SECTION ONE: GENERAL
The clauses and subclauses of this section of the General Standard apply except as follows:

1 Scope and object
This clause of the General Standard applies except as follows:
*1.1 Scope
Addition:
This Particular Standard specifies particular safety requirements for ULTRASONIC DIAGNOSTIC
EQUIPMENT as defined in 2.1.145.
This standard does not cover ultrasonic therapeutic equipment; however, equipment used for
the imaging of body structures by ultrasound in conjunction with therapeutic modalities is
covered.
1.2 Object
Replacement:
The object of this Particular Standard is to establish particular requirements for the safety of
ULTRASONIC DIAGNOSTIC EQUIPMENT and those aspects thereof which are directly related to
safety.
1.3 Particular Standards
Addition:
This Particular Standard amends and supplements a set of IEC publications, hereinafter

referred to as the “General Standard”, consisting of
IEC 60601-1:1988, Medical electrical equipment – Part 1: General requirements for safety and
its Amendments 1 (1991) and 2 (1995)
IEC 60601-1-2:2001, Medical electrical equipment – Part 1-2: General requirements for
safety – Collateral standard: Electromagnetic compatibility – Requirements and tests
IEC 60601-1-4:1996, Medical electrical equipment – Part 1-4: General requirements for
safety – 4. Collateral Standard: Programmable electrical medical systems and its Amendment 1
(1999)
The numbering of sections, clauses and subclauses of this Particular Standard corresponds to
that of the General Standard. The changes to the text of the General Standard are specified
by the use of the following words:

– 8 – 60601-2-37  IEC:2001+A1:2004(E)

“Replacement” means that the clause or subclause of the General 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.
“Amendment” means that the clause or subclause of the General Standard is amended as

indicated by the text of this Particular Standard.

Subclauses or figures which are additional to those of the General Standard are numbered

starting from 101, additional annexes are lettered AA, BB, etc., and additional items aa), bb), etc.

Clauses and subclauses to which there is a rationale are marked with an asterisk (*). These
rationales can be found in an informative annex BB. Annex BB should be used in determining
the relevance of the requirements addressed, but should never be used to establish additional
test requirements.
Where there is no corresponding section, clause or subclause in this Particular Standard, the
section, clause or subclause of the General Standard applies without modification.
Where it is intended that any part of the General Standard, although possibly relevant, is not
to be applied, a statement to that effect is given in this Particular Standard.
A requirement of this Particular Standard replacing or modifying requirements of the General
Standard or of a Collateral Standard takes precedence over the corresponding general
requirement(s).
1.3.101 Related international standards
IEC 60529:1989, Degrees of protection provided by enclosures (IP Code)
IEC 60788:1984, Medical radiology – Terminology
IEC 61102:1991, Measurement and characterisation of ultrasonic fields using hydrophones in
the frequency range 0,5 MHz to 15 MHz
IEC 61157:1992, Requirements for the declaration of the acoustic output of medical
diagnostic ultrasonic equipment
IEC 61161:1992, Ultrasonic power measurement in liquids in the frequency range 0,5 MHz to
25 MHz
Amendment 1 (1998)
2 Terminology and definitions
This clause of the General Standard applies except as follows:
Additional definitions:
2.1.101
ACOUSTIC ATTENUATION COEFFICIENT
coefficient intended to account for ultrasonic attenuation of tissue between the source and a
specified point
Symbol: α
–1 –1
Unit: decibels per centimetre per megahertz, dB cm MHz

60601-2-37 © IEC:2001+A1:2004 (E) – 9 –

2.1.102
ACOUSTIC WORKING FREQUENCY
arithmetic mean of the most widely separated frequencies f and f at which the amplitude of
1 2
the pressure spectrum of the acoustic signal is 3 dB lower than the peak amplitude

[3.4.2 of IEC 61102, modified]

Symbol: f
awf
Unit: megahertz, MHz
2.1.103
ATTENUATED OUTPUT POWER
value of the acoustic OUTPUT POWER after attenuation and at a specified distance from the
transducer, and given by
(-α z f /10)
awf
P = P 10
α
where
α is the ACOUSTIC ATTENUATION COEFFICIENT in decibels per centimetre per megahertz;
z is the distance from the source to the point of interest in centimetres;
f is the ACOUSTIC WORKING FREQUENCY in megahertz;
awf
P is the ATTENUATED OUTPUT POWER in milliwatts;
α
P is the OUTPUT POWER in milliwatts measured in water.
Symbol: P
α
Unit: milliwatts, mW
2.1.104
ATTENUATED PEAK-RAREFACTIONAL ACOUSTIC PRESSURE
value of the PEAK-RAREFACTIONAL ACOUSTIC PRESSURE after attenuation and at a specified
point, and given by
(-α z f /20)
awf
p (z) = p (z) 10
ra r
where
α is the ACOUSTIC ATTENUATION COEFFICIENT in decibels per centimetre per megahertz;
z is the distance from the source to the point of interest, in centimetres;
f is the ACOUSTIC WORKING FREQUENCY in megahertz;
awf
p (z) is the PEAK-RAREFACTIONAL ACOUSTIC PRESSURE measured in water.

r
Symbol: p
ra
Unit: megapascals, MPa
– 10 – 60601-2-37  IEC:2001+A1:2004(E)

2.1.105
ATTENUATED PULSE-AVERAGE INTENSITY

value of the acoustic PULSE-AVERAGE INTENSITY after attenuation and at a specified point, and

given by
(-α z f /10)
awf
I = I (z) 10
pa,α pa
where
α is the ACOUSTIC ATTENUATION COEFFICIENT in decibels per centimetre per megahertz;

z is the distance from the source to the point of interest in centimetres;

f is the ACOUSTIC WORKING FREQUENCY, at distance z in megahertz;
awf
I (z) is the PULSE-AVERAGE INTENSITY measured in water, in milliwatts per centimetre
pa
squared.
Symbol: I
pa,α
–2
Unit: watts per centimetre squared, W cm
2.1.106
ATTENUATED PULSE-INTENSITY INTEGRAL
value of the PULSE-INTENSITY INTEGRAL after attenuation and at a specified point, and given by
(-α z f /10)
awf
I = I 10
pi,α pi
where
α is the ACOUSTIC ATTENUATION COEFFICIENT in decibels per centimetre per megahertz;
z is the distance from the source to the point of interest in centimetres;
f is the ACOUSTIC WORKING FREQUENCY in megahertz;
awf
I is the ATTENUATED PULSE-INTENSITY INTEGRAL in millijoules per centimetre squared;
pi,α
I is the PULSE-INTENSITY INTEGRAL measured in water in millijoules per centimetre
pi
squared.
Symbol: I
pi,α
–2
Unit: millijoules per centimetre squared, mJ cm
2.1.107
ATTENUATED SPATIAL-PEAK TEMPORAL-AVERAGE INTENSITY
value of the SPATIAL-PEAK TEMPORAL AVERAGE INTENSITY after attenuation and at a specified

distance z, and given by
(-α z f /10)
awf
I (z) = I (z) 10
zpta,α zpta
where
α is the ACOUSTIC ATTENUATION COEFFICIENT in decibels per centimetre per megahertz;
z is the distance from the source to the point of interest in centimetres;
f is the ACOUSTIC WORKING FREQUENCY in megahertz;
awf
I (z) is the SPATIAL-PEAK TEMPORAL-AVERAGE INTENSITY, at a specified distance z in milliwatts
zpta
per centimetre squared measured in water.
Symbol: I (z)
zpta,α
–2
Unit: milliwatts per centimetre squared, mW cm

60601-2-37 © IEC:2001+A1:2004 (E) – 11 –

2.1.108
ATTENUATED TEMPORAL-AVERAGE INTENSITY

value of the TEMPORAL-AVERAGE INTENSITY after attenuation and at a specified point, and given by

( -α z f /10)
awf
I (z) = I (z) 10
ta,α ta
where
α is the ACOUSTIC ATTENUATION COEFFICIENT in decibels per centimetre per megahertz;

z is the distance from the source to the point of interest in centimetres;

f is the ACOUSTIC WORKING FREQUENCY in megahertz;
awf
I (z) is the ATTENUATED TEMPORAL-AVERAGE INTENSITY in milliwatts per centimetre squared;
ta,α
I (z) is the TEMPORAL-AVERAGE INTENSITY measured in water in milliwatts per centimetre
ta
squared.
Symbol: I (z)
ta,α
–2
Unit: milliwatts per centimetre squared, mW cm
2.1.109
BEAM AREA
area in a specified plane perpendicular to the BEAM-ALIGNMENT AXIS consisting of all points at
which the PULSE-INTENSITY INTEGRAL is greater than a specified fraction of the maximum
PULSE-INTENSITY INTEGRAL in that plane
[3.6 of IEC 61102, modified]
NOTE For measurement purposes the PULSE INTENSITY INTEGRAL can be taken as being proportional to the PULSE
PRESSURE-SQUARED INTEGRAL
2.1.110
BEAM ALIGNMENT AXIS
straight line joining the points of maximum PULSE INTENSITY INTEGRAL measured at several
different distances in the far field. For the purposes of alignment, this line may be projected to
the face of the ULTRASONIC TRANSDUCER
[3.5 of IEC 61102, modified]
2.1.111
BONE THERMAL INDEX
THERMAL INDEX for applications, such as foetal (second and third trimester) or neonatal
cephalic (through the fontanelle), in which the ultrasound beam passes through soft tissue
and a focal region is in the immediate vicinity of bone
Symbol: TIB
Unit: None
NOTE See annex DD.4.2 and DD.5.2 for methods of determining the BONE THERMAL INDEX.
2.1.112
BOUNDED OUTPUT POWER
OUTPUT POWER emitted in SCANNING MODE from a region of the active area of the transducer
whose width in the scan plane is limited to 1 cm
Symbol: P
Unit: milliwatts, mW
– 12 – 60601-2-37  IEC:2001+A1:2004(E)

2.1.113
BREAK-POINT DEPTH
value equal to 1,5 times the EQUIVALENT APERTURE DIAMETER, and given by

z = 1,5 D
bp eq
where
D is the EQUIVALENT APERTURE DIAMETER.
eq
Symbol: z
bp
Unit: centimetres, cm
2.1.114
COMBINED-OPERATING MODE
mode of operation of an EQUIPMENT which combines more than one DISCRETE-OPERATING MODE
[3.6 of IEC 61157]
2.1.115
CRANIAL-BONE THERMAL INDEX
THERMAL INDEX for applications, such as paediatric and adult cranial applications, in which the
ultrasound beam passes through bone near the beam entrance into the body
Symbol: TIC
Unit: None
NOTE See annex DD.4.3 for methods of determining the CRANIAL BONE THERMAL INDEX.
2.1.116
DEFAULT SETTING
specific state of control, the ULTRASONIC DIAGNOSTIC EQUIPMENT will enter upon power-up, new
PATIENT select or change from non-foetal to foetal applications
2.1.117
DEPTH FOR BONE THERMAL INDEX
distance from the plane where the –12 dB OUTPUT BEAM DIMENSIONS are determined along the
BEAM ALIGNMENT AXIS to the plane where the product of ATTENUATED OUTPUT POWER and
ATTENUATED PULSE-INTENSITY INTEGRAL is maximum
Symbol: z
b
Unit: centimetres, cm
2.1.118
DEPTH FOR SOFT-TISSUE THERMAL INDEX

distance from the plane where the –12 dB OUTPUT BEAM DIMENSIONS are determined along the
BEAM ALIGNMENT AXIS to the plane at which the lower value of the ATTENUATED OUTPUT POWER
and the product of the ATTENUATED SPATIAL-PEAK TEMPORAL-AVERAGE INTENSITY and 1 cm is
maximized over the distance range equal to, or more than, 1,5 times the EQUIVALENT
APERTURE DIAMETER
Symbol: z
s
Unit: centimetres, cm
NOTE In this Particular Standard, the restricted definition of SPATIAL-PEAK TEMPORAL-AVERAGE INTENSITY from 3.49
of IEC 61102 relating to a specified plane is used where SPATIAL-PEAK TEMPORAL-AVERAGE INTENSITY is replaced by
ATTENUATED SPATIAL-PEAK TEMPORAL-AVERAGE INTENSITY.
2.1.119
DISCRETE-OPERATING MODE
mode of operation of ULTRASONIC DIAGNOSTIC EQUIPMENT in which the purpose of the excitation
of the ULTRASONIC TRANSDUCER or ULTRASONIC TRANSDUCER element group is to utilize only
one diagnostic methodology
[3.7 of IEC 61157]
60601-2-37 © IEC:2001+A1:2004 (E) – 13 –

2.1.120
EQUIVALENT APERTURE DIAMETER
diameter of a circle whose area is the –12 dB OUTPUT BEAM AREA and given by

D ≡ A
eq aprt
π
where
is the –12 dB OUTPUT BEAM AREA.
A
aprt
Symbol: D
eq
Unit: centimetres, cm
NOTE This formula gives the diameter of a circle whose area is the –12 dB OUTPUT BEAM AREA. It is used in the
calculation of the CRANIAL-BONE THERMAL INDEX and the SOFT TISSUE THERMAL INDEX.
2.1.121
EQUIVALENT BEAM AREA
value of the area of the acoustic beam at the distance z in terms of power and intensity, and given by
P
P
α
A (z) ≡ =
eq
I (z) I (z)
zpta,α zpta
where
P (z) is the ATTENUATED OUTPUT POWER, at the distance z, in milliwatts;
α
I (z) is the ATTENUATED SPATIAL-PEAK TEMPORAL-AVERAGE INTENSITY, at the distance z,
zpta,α
in milliwatts per square centimetre;
P is the OUTPUT POWER in milliwatts;
I (z) is the SPATIAL-PEAK TEMPORAL-AVERAGE INTENSITY, at the distance z, in milliwatts per
zpta
square centimetre; and
z is the distance from the source to the specified point in centimetres.
Symbol: A (z)
eq
Unit: centimetres squared, cm
2.1.122
EQUIVALENT BEAM DIAMETER
value of the diameter of the acoustic beam at the distance z in terms of the EQUIVALENT BEAM
AREA, and given by
d (z) = A (z)
eq eq
π
where
A (z) is the EQUIVALENT BEAM AREA;
eq
z is the distance from the source to the specified point.
Symbol: d (z)
eq
Unit: centimetres, cm
2.1.123
FULL SOFTWARE CONTROL OF ACOUSTIC OUTPUT
means by which the EQUIPMENT establishes values of the acoustic output quantities
independent of direct OPERATOR control

– 14 – 60601-2-37  IEC:2001+A1:2004(E)

2.1.124
MECHANICAL INDEX
the displayed parameter representing potential cavitation bio-effects

NOTE See DD.2.2 for methods of determining the MECHANICAL INDEX.

2.1.125
MULTI-PURPOSE ULTRASONIC EQUIPMENT

ultrasonic equipment which is intended for more than one clinical application

2.1.126
NON-SCANNING MODE
mode of operation of ULTRASONIC DIAGNOSTIC EQUIPMENT that involves a sequence of
ultrasonic pulses which give rise to ultrasonic scan lines that follow the same acoustic path
[3.12 of IEC 61157, modified]
2.1.127
–12 dB OUTPUT BEAM AREA
area of the ultrasonic beam derived from the –12 dB OUTPUT BEAM DIMENSIONS
[3.13 of IEC 61157, modified]
Symbol: A
aprt
Unit: centimetre squared, cm
2.1.128
–12 dB OUTPUT BEAM DIMENSIONS
dimensions of the ultrasonic beam (–12 dB PULSE BEAM WIDTH) in specified directions normal
to the BEAM ALIGNMENT AXIS and at the transducer output face
[3.14 of IEC 61157, modified]
NOTE 1 For reasons of measurement accuracy the –12 dB OUTPUT BEAM DIMENSIONS can be derived from
measurements at a distance chosen to be as close as possible to the face of the transducer, and if possible no
more than 1 mm from the face (3.14 of IEC 61157, modified).
NOTE 2 For contact transducers, these dimensions can be taken as the dimensions of the radiating element.
Symbol: X, Y
Unit: centimetres, cm
2.1.129
OUTPUT POWER
time-average power radiated by an ULTRASONIC TRANSDUCER into an approximately free field under
specified conditions in a specified medium, preferably water
[3.5 of IEC 61161, modified]
Symbol: P
Unit: milliwatts, mW
2.1.130
PEAK-RAREFACTIONAL ACOUSTIC PRESSURE
maximum of the modulus of the negative instantaneous acoustic pressure in an acoustic field
during an acoustic repetition period
[3.34 of IEC 61157, modified]
Symbol: p
r
Unit: megapascals, MPa
2.1.131
PRUDENT-USE STATEMENT
affirmation of the principle advising avoidance of primarily high exposure levels and
secondarily long exposure times while acquiring necessary clinical information

60601-2-37 © IEC:2001+A1:2004 (E) – 15 –

2.1.132
PULSE-AVERAGE INTENSITY
ratio of the PULSE INTENSITY INTEGRAL I to the PULSE DURATION t
pi d
Symbol: I
pa
–2
Unit: watts per square centimetre, W cm

2.1.133
PULSE BEAM-WIDTH
distance between two points, on a specified surface in a specified direction passing through the

point of maximum PULSE-PRESSURE-SQUARED INTEGRAL (p) in that surface, at which the PULSE-
i
PRESSURE-SQUARED INTEGRAL is a specified fraction of the maximum value in that surface
[3.18 of IEC 61157, modified]
Symbol: d (for PULSE BEAM-WIDTH defined at –6dB)
–6
Unit: centimetres, cm
2.1.134
PULSE DURATION
1,25 times the interval between the time when the time integral of intensity in an acoustic
pulse at a point reaches 10 % and when it reaches 90 % of the PULSE INTENSITY INTEGRAL
[3.30 of IEC 61102, modified]
Symbol: t
d
Unit: seconds, s
2.1.135
PULSE-INTENSITY INTEGRAL
time integral of the instantaneous intensity at a particular point in an acoustic field integrated
over the acoustic pulse waveform
[3.31 of IEC 61102]
Symbol: I
pi
–2
Unit: millijoules per centimetre squared, mJ cm
2.1.136
PULSE-PRESSURE-SQUARED INTEGRAL
time integral of the square of the instantaneous acoustic pressure at a particular point in an
acoustic field integrated over the acoustic pulse waveform

[3.33 of IEC 61102]
Symbol: p
i
Unit: Pascal squared seconds, Pa s

2.1.137
PULSE REPETITION RATE
inverse of the time interval between two successive acoustic pulses
[3.35 of IEC 61102, modified]
Symbol: prr
Unit: hertz, Hz
2.1.138
SCANNING MODE
mode of operation of an ULTRASONIC DIAGNOSTIC EQUIPMENT that involves a sequence of
ultrasonic pulses which give rise to scan lines that do not follow the same acoustic path
[3.21 of IEC 61157, modified]
– 16 – 60601-2-37  IEC:2001+A1:2004(E)

2.1.139
SOFT TISSUE THERMAL INDEX
THERMAL INDEX related to soft tissues

Symbol: TIS
Unit: None
NOTE 1 See annex DD.5.1 and the following for methods of determination of the SOFT-TISSUE THERMAL INDEX.

NOTE 2 For the purposes of this document, soft tissue includes all body tissues and fluids but excludes skeletal

tissues
2.1.140
SPATIAL-PEAK TEMPORAL-AVERAGE INTENSITY
maximum value of the TEMPORAL-AVERAGE INTENSITY in a specified plane at a specified
distance z from the transducer
[3.49 of IEC 61102, modified]
Symbol: I (z)
zpta
–2
Unit: milliwatts per centimetre squared, mW cm
NOTE In this standard the restricted definition from 3.49 of IEC 61102 relating to a specified plane is used.
2.1.141
TEMPORAL-AVERAGE INTENSITY
time-average of the instantaneous intensity at a particular point in an acoustic field
[3.53 of IEC 61102, modified]
Symbol: I (z)
ta
–2
Unit: milliwatts per centimetre squared, mW cm
2.1.142
THERMAL INDEX
ratio of attenuated acoustic power at a specified point to the attenuated acoustic power
required to raise the temperature at that point in a specific tissue model by 1 °C
Symbol: TI
Unit: None
2.1.143
TRANSDUCER ASSEMBLY
transducer housing (probe), any associated electronic circuitry and any liquids contained in the
housing and the integral cable which connects the transducer probe to an ultrasound console
[see 3.22 of IEC 61157]
2.1.144
TRANSMIT PATTERN
combination of a specific set of transducer beam-forming characteristics (determined by the
transmit aperture size, apodization shape and relative timing/phase delay pattern across the
aperture, resulting in a specific focal length and direction), and an electrical drive waveform of
a specific fixed shape but variable amplitude
2.1.145
ULTRASONIC DIAGNOSTIC EQUIPMENT
MEDICAL ELECTRICAL EQUIPMENT which is intended for in vivo ultrasonic and monitoring
examination for obtaining a medical diagnosis
NOTE See also definition 3.11 of IEC 61157: medical diagnostic ultrasonic equipment (or system) – combination
of the ultrasound instrument console and the TRANSDUCER ASSEMBLY making up a complete diagnostic system.

60601-2-37 © IEC:2001+A1:2004 (E) – 17 –

2.1.146
ULTRASONIC TRANSDUCER
device capable of converting electrical energy to mechanical energy and/or mechanical

energy to electrical energy, both within the ultrasonic frequency range

2.1.147
ESSENTIAL PERFORMANCE
performance characteristics necessary to maintain the RESIDUAL RISK within acceptable limits

[IEC 60601-1-2, definition 2.210]

NOTE See also 3.201.2 of IEC 60601-1-2.

2.101 List of symbols
ACOUSTIC ATTENUATION COEFFICIENT
α
A –12dB OUTPUT BEAM AREA
aprt
C NORMALIZING COEFFICIENT
MI
D EQUIVALENT APERTURE DIAMETER
eq
d PULSE BEAM WIDTH
–6
d EQUIVALENT BEAM DIAMETER
eq
f ACOUSTIC WORKING FREQUENCY
awf
I PULSE-AVERAGE INTENSITY
pa
I ATTENUATED PULSE-AVERAGE INTENSITY
pa,α
I PULSE-INTENSITY INTEGRAL
pi
I ATTENUATED PULSE-INTENSITY INTEGRAL
pi,α
(z)
I TEMPORAL-AVERAGE INTENSITY
ta
I (z) ATTENUATED TEMPORAL-AVERAGE INTENSITY
ta,α
I (z) SPATIAL-PEAK TEMPORAL-AVERAGE INTENSITY
zpta
I (z) ATTENUATED SPATIAL-PEAK TEMPORAL-AVERAGE INTENSITY
zpta,α
MI MECHANICAL INDEX
P OUTPUT POWER
P ATTENUATED OUTPUT POWER
α
P BOUNDED OUTPUT POWER
p PULSE PRESSURE SQUARED INTEGRAL
i
p PEAK-RAREFACTIONAL ACOUSTIC PRESSURE
r
p ATTENUATED PEAK-RAREFACTIONAL ACOUSTIC PRESSURE
ra
prr PULSE REPETITION RATE
TI THERMAL INDEX
TIB BONE THERMAL INDEX
TIC CRANIAL-BONE THERMAL INDEX
TIS SOFT-TISSUE THERMAL INDEX
t PULSE DURATION
d
X, Y –12 dB OUTPUT BEAM DIMENSIONS
z DISTANCE FROM THE SOURCE TO A SPECIFIED POINT
z DEPTH FOR TIB
b
z BREAK-POINT DEPTH
bp
z DEPTH FOR TIS
s
– 18 – 60601-2-37  IEC:2001+A1:2004(E)

3 General requirements
This clause of the General Standard applies except as follows:

*3.101 ESSENTIAL PERFORMANCE
NOTE See 2.1.145 for intended use definition of ULTRASONIC DIAGNOSTIC EQUIPMENT.

The following are the potential sources of harm identified as characterizing the ESSENTIAL

PERFORMANCE of ULTRASONIC DIAGNOSTIC EQUIPMENT:

– noise on a waveform, artefacts, distortion in an image or error of a displayed numerical
value which cannot be attributed to a physiological effect and which may alter the
diagnosis;
– the display of inaccurate numerical values associated with the diagnosis to be performed;
– the display of inaccurate safety-related indications;
– the production of unintended or excessive ultrasound output;
– the production of unintended or excessive TRANSDUCER ASSEMBLY surface temperature;
– the production of unintended or uncontrolled motion of TRANSDUCER ASSEMBLIES intended
for intra-corporeal use.
In some circumstances the need for the repetition of an ultrasound examination should be
evaluated as a potential hazard, for example, intra-corporeal investigation and stress testing
for cardiopathic PATIENTS.
6 Identification, marking and documents
This clause of the General Standard applies except as follows:
6.1 Marking on the outside of EQUIPMENT or EQUIPMENT parts
Addition:
aa) Compliance with EMC requirements
Intra-corporal TRANSDUCER ASSEMBLIES that do not comply with the electromagnetic
compliance requirements of clause 36 shall have applied the following IEC symbol to the
TRANSDUCER ASSEMBLY: symbol 14 of table DI in annex D of the General Standard.
Replacement:
*p) Output
For ULTRASONIC DIAGNOSTIC EQUIPMENT capable of generating output levels subject to 51.2
bb), cc) or dd), and which allows the OPERATOR to directly vary the output levels, the
action needed to increase or decrease the output levels shall be clear to the OPERATOR.
This marking shall be of the nature of an active DISPLAY.
Replacement:
q) Physiological effects, symbols and warning statements
MULTI-PURPOSE ULTRASONIC EQUIPMENT capable of ultrasound output levels subject to 51.2
bb) or dd) should carry the marking described as symbol 14 in table DI of annex D of the
General Standard, affixed to the CONTROL PANEL or other readily visible location. The
purpose of this marking is to alert the OPERATOR to consult the INSTRUCTIONS FOR USE
before operation of the ULTRASONIC DIAGNOSTIC EQUIPMENT.

60601-2-37 © IEC:2001+A1:2004 (E) – 19 –

6.3 Marking of controls and instruments

Additional items:
aa) A display of THERMAL INDEX and MECHANICAL INDEX shall be provided in accordance with

the requirements of 51.2, together with the declaration of accuracy described in 6.8.2

and 50.2.
bb) A display of the surface temperature of ULTRASONIC TRANSDUCERS intended for trans-

oesophageal use shall be provided in accordance with 42.3, 50.2, and 51.2.

cc) A display relevant to ultrasound output levels (see 51.2) shall be clearly visible from the

OPERATOR’S position, with the full name(s) or abbreviation(s) of the index (indices)

displayed.
6.8.2 INSTRUCTIONS FOR USE
Additional items:
aa) INSTRUCTIONS FOR USE shall contain the following:
1) the procedures necessary for safe operation, drawing attention to the safety hazards
which may occur as a result of an inadequate electrical installation when the APPLIED
PART of the ULTRASONIC DIAGNOSTIC EQUIPMENT is of TYPE B;
2) the type of electrical installation to which the ULTRASONIC DIAGNOSTIC EQUIPMENT may
be safely connected, including the connection of any POTENTIAL EQUALIZATION
CONDUCTOR;
3) the safe use of internal and external TRANSDUCER ASSEMBLIES, and in particular that
the ULTRASONIC DIAGNOSTIC EQUIPMENT is of the correct type for its intended applic-
ation; for TRANSDUCER ASSEMBLIES intended for intra-corporeal use, a warning in the
instructions not to activate the TRANSDUCER ASSEMBLY outside the PATIENT’s body if
the TRANSDUCER ASSEMBLY, when so activated, would not comply with
electromagnetic compliance requirements and may cause harmful interference with
other equipment in the environment. The identification of interference with other
equipment and mitigation techniques shall be included in the INSTRUCTIONS FOR USE if
a reduction in test levels is claimed by the MANUFACTURER;
4) a description of those parts of the TRANSDUCER ASSEMBLY which may be immersed in
water or other liquids either for NORMAL USE or performance assessment purposes;
5) a notice if the ULTRASONIC DIAGNOSTIC EQUIPMENT or parts thereof are provided with
protective means against burns to the PATIENT when used with HF surgical
equipment. If no such means are incorporated, notice shall be given in the
ACCOMPANYING DOCUMENTS and advice shall be given regarding the location and use
of the TRANSDUCER ASSEMBLY to reduce the hazard of burns in the event of a defect in

the HF surgical neutral electrode con
...