IEC 62359:2005

INTERNATIONAL IEC
STANDARD 62359
First edition
2005-04
Ultrasonics –
Field characterization –
Test methods for the determination of
thermal and mechanical indices related
to medical diagnostic ultrasonic fields

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INTERNATIONAL IEC
STANDARD 62359
First edition
2005-04
Ultrasonics –
Field characterization –
Test methods for the determination of
thermal and mechanical indices related
to medical diagnostic ultrasonic fields

 IEC 2005  Copyright - all rights reserved
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– 2 – 62359  IEC:2005(E)
CONTENTS
FOREWORD.3

INTRODUCTION.5

1 Scope.6

2 Normative references .6

3 Terms and definitions .6

4 List of symbols .15

5 Test methods for determining the mechanical index and the thermal index .16
5.1 General .16
5.2 Determination of mechanical index .17
5.3 Determination of thermal index – general .17
5.4 Determination of thermal index in non-scanning mode.17
5.5 Determination of thermal index in scanning mode.19
5.6 Calculations for combined-operating mode .19
5.7 Summary of measured quantities for index determination .20

Annex A (informative) Relationships with other standards .22
Annex B (informative) Guidance notes for measurement of output power
in scanning mode.23
Annex C (informative) Rationale and derivation of index models .27
Annex D (informative) Guidance on the interpretation of TI and MI .40

Bibliography.41

Figure B.1 – Suggested 1 cm-wide aperture mask .25
Figure B.2 – Suggested orientation of transducer, mask slit and RFB target .25
Figure B.3 – Suggested orientation of transducer and 1 cm RFB target .25
Figure C.1 – Focused transducer with a large aperture .35
Figure C.2 – Focused transducer with smaller aperture (≥1 cm ).35
Figure C.3 – Focused transducer with a weak focus (A > 1 cm ).36

eq
Figure C.4 – Weakly focused transducer.36

Table 1 – Summary of combination formulae for each of the THERMAL INDEX categories.20
Table 2 – Summary of the acoustic quantities required for the determination of the indices .21
Table C.1 – THERMAL INDEX categories and models .29
Table C.2 – Thermal index formulae .33

62359  IEC:2005(E) – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION

____________
ULTRASONICS –
FIELD CHARACTERIZATION –
TEST METHODS FOR THE DETERMINATION OF THERMAL

AND MECHANICAL INDICES RELATED TO

MEDICAL DIAGNOSTIC ULTRASONIC FIELDS

FOREWORD
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International Standard IEC 62359 has been prepared by IEC technical committee 87:
Ultrasonics
The text of this standard is based on the following documents:
FDIS Report on voting
87/300/FDIS 87/305/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 2.
This standard may be used to support the requirements of IEC 60601-2-37.

– 4 – 62359  IEC:2005(E)
The committee has decided that the contents of this publication 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.

62359  IEC:2005(E) – 5 –
INTRODUCTION
Medical diagnostic ultrasonic equipment is widely used in clinical practice for imaging and

monitoring purposes. Equipment normally operates at frequencies in the low megahertz

frequency range and comprises an ultrasonic transducer acoustically coupled to the patient

and associated electronics. There is an extremely wide range of different types of systems in

current clinical practice.
The ultrasound entering the patient interacts with the patient's tissue and this interaction can

be considered in terms of both thermal and non-thermal effects. The purpose of this

International Standard is to specify methods of determining thermal and non-thermal exposure

indices which can be used to help in assessing the hazard caused by exposure to a particular
ultrasonic field used for medical diagnosis or monitoring. It is recognised that these indices
have limitations and a knowledge of the indices at the time of an examination is not sufficient
in itself to make an informed clinical risk assessment. It is intended that these limitations will
be addressed in future revisions of this standard and as scientific understanding increases.
Under certain conditions specified in IEC 60601-2-37 these indices are displayed on medical
ultrasonic equipment intended for these purposes.

– 6 – 62359  IEC:2005(E)
ULTRASONICS –
FIELD CHARACTERIZATION –
TEST METHODS FOR THE DETERMINATION OF THERMAL

AND MECHANICAL INDICES RELATED TO

MEDICAL DIAGNOSTIC ULTRASONIC FIELDS

1 Scope
This International Standard is applicable to medical diagnostic ultrasound fields.

This standard establishes
– parameters related to thermal and non-thermal aspects of diagnostic ultrasonic fields;
– methods for the determination of an exposure parameter relating to temperature rise in
theoretical tissue-equivalent models, resulting from absorption of ultrasound;
– methods for the determination of an exposure parameter appropriate to certain non-
thermal effects.
NOTE In this standard where multiples or submultiples of SI units are used this is clearly stated and the usage is
self-consistent.
2 Normative references
The following referenced documents are indispensable for the application of this document.
For dated references, only the edition cited applies. For undated references, the latest edition
of the referenced document (including any amendments) applies.
IEC 60601-2-37, Medical electrical equipment – Part 2-37: Particular requirements for the
safety of ultrasonic medical diagnostic and monitoring equipment
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
1)
25 MHz
Amendment 1 (1998)
3 Terms and definitions
For the purposes of this International standard, the terms and definitions given in
IEC 61102:1991, IEC 61157:1992 and IEC 61161:1998 (several of which are repeated below
for convenience) and the following apply.
3.1
acoustic attenuation coefficient
coefficient intended to account for ultrasonic attenuation of tissue between the source and a
specified point
Symbol: α
–1
...