SIST EN 62555:2014

SLOVENSKI STANDARD
SIST EN 62555:2014
01-junij-2014
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Ultrasonics - Power measurement - Output power measurement for high intensity
therapeutic ultrasound (HITU) transducers and systems
/
Ultrasons - Mesurage de puissance - Transducteurs et systèmes ultrasonores
thérapeutiques de haute intensité (HITU)
Ta slovenski standard je istoveten z: EN 62555:2014
ICS:
17.140.50 Elektroakustika Electroacoustics
SIST EN 62555:2014 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN 62555:2014

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SIST EN 62555:2014

EUROPEAN STANDARD
EN 62555

NORME EUROPÉENNE
April 2014
EUROPÄISCHE NORM

ICS 17.140.50


English version


Ultrasonics -
Power measurement -
High intensity therapeutic ultrasound (HITU) transducers and systems
(IEC 62555:2013)


Ultrasons -  Ultraschall -
Mesurage de puissance - Leistungsmessung -
Transducteurs et systèmes ultrasonores Messung der Ausgangsleistung für
thérapeutiques de haute intensité (HITU) hochintensive, therapeutische
(CEI 62555:2013) Ultraschallwandler und -systeme
(IEC 62555:2013)



This European Standard was approved by CENELEC on 2013-12-24. CENELEC members are bound to comply
with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard
the status of a national standard without any alteration.

Up-to-date lists and bibliographical references concerning such national standards may be obtained on
application to the CEN-CENELEC Management Centre or to any CENELEC member.

This European Standard exists in three official versions (English, French, German). A version in any other
language made by translation under the responsibility of a CENELEC member into its own language and notified
to the CEN-CENELEC Management Centre has the same status as the official versions.

CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus,
the Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany,
Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland,
Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom.

CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung

CEN-CENELEC Management Centre: Avenue Marnix 17, B - 1000 Brussels


© 2014 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 62555:2014 E

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SIST EN 62555:2014
EN 62555:2014 - 2 -

Foreword
The text of document 87/538/FDIS, future edition 1 of IEC 62555, prepared by IEC TC 87 "Ultrasonics"
was submitted to the IEC-CENELEC parallel vote and approved by CENELEC as EN 62555:2014.
The following dates are fixed:
• latest date by which the document has (dop) 2014-10-25
to be implemented at national level by
publication of an identical national
standard or by endorsement
• latest date by which the national (dow) 2016-12-24
standards conflicting with the
document have to be withdrawn

Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CENELEC [and/or CEN] shall not be held responsible for identifying any or all such patent
rights.
Endorsement notice
The text of the International Standard IEC 62555:2013 was approved by CENELEC as a European
Standard without any modification.
In the official version, for Bibliography, the following notes have to be added for the standards indicated:
IEC 62127-2 NOTE  Harmonized as EN 62127-2
IEC 60601-2-62 NOTE  Harmonized as EN 60601-2-62

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SIST EN 62555:2014
- 3 - EN 62555:2014
Annex ZA
(normative)

Normative references to international publications
with their corresponding European publications

The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.

NOTE  When an international publication has been modified by common modifications, indicated by (mod), the relevant EN/HD
applies.

Publication Year Title EN/HD Year

IEC 61161 2013 Ultrasonics - Power measurement - Radiation EN 61161 2013
force balances and performance requirements


IEC/TR 62781 Ultrasonics - Conditioning of water for - -
ultrasonic measurements

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SIST EN 62555:2014

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SIST EN 62555:2014



IEC 62555

®


Edition 1.0 2013-11




INTERNATIONAL



STANDARD




NORME



INTERNATIONALE











Ultrasonics – Power measurement – High intensity therapeutic ultrasound (HITU)

transducers and systems




Ultrasons – Mesurage de puissance – Transducteurs et systèmes ultrasonores

thérapeutiques de haute intensité (HITU)
















INTERNATIONAL

ELECTROTECHNICAL

COMMISSION


COMMISSION

ELECTROTECHNIQUE

PRICE CODE
INTERNATIONALE

CODE PRIX XA


ICS 17.140.50 ISBN 978-2-8322-1163-2



Warning! Make sure that you obtained this publication from an authorized distributor.

Attention! Veuillez vous assurer que vous avez obtenu cette publication via un distributeur agréé.

® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale

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SIST EN 62555:2014
– 2 – 62555 © IEC:2013
CONTENTS
FOREWORD . 5
INTRODUCTION . 7
1 Scope . 8
2 Normative references . 8
3 Terms and definitions . 8
4 List of symbols . 11
5 Power measurement for HITU equipment. 12
6 Radiation force on a target . 13
6.1 General . 13
6.2 Requirements for equipment . 14
6.2.1 Target type . 14
6.2.2 Target diameter . 15
6.2.3 Balance / force measuring system . 15
6.2.4 System tank . 15
6.2.5 Target support structures . 15
6.2.6 Transducer positioning . 15
6.2.7 Anti-streaming foils . 15
6.2.8 Transducer coupling . 16
6.2.9 Calibration and stability . 16
6.3 Requirements for measuring conditions . 16
6.3.1 Lateral target position . 16
6.3.2 Transducer/target separation . 16
6.3.3 Water . 16
6.3.4 Water contact . 17
6.3.5 Environmental conditions . 17
6.3.6 Thermal drifts . 17
6.4 Measurement uncertainty . 17
6.4.1 General . 17
6.4.2 Non-planar ultrasound field . 17
6.4.3 Balance system with target suspension. 17
6.4.4 Linearity and resolution of the balance system . 17
6.4.5 Extrapolation to the moment of switching the ultrasonic
transducer . 18
6.4.6 Target imperfections . 18
6.4.7 Reflecting target geometry . 18
6.4.8 Lateral absorbers in the case of reflecting target
measurements . 18
6.4.9 Target misalignment . 18
6.4.10 Ultrasonic transducer misalignment . 18
6.4.11 Water temperature . 18
6.4.12 Ultrasonic attenuation and acoustic streaming . 19
6.4.13 Foil properties . 19
6.4.14 Finite target size . 19
6.4.15 Environmental influences . 19
6.4.16 Excitation voltage measurement . 19
6.4.17 Ultrasonic transducer temperature . 19
6.4.18 Nonlinearity . 19

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SIST EN 62555:2014
62555 © IEC:2013 – 3 –
6.4.19 Other sources . 19
6.5 Calculation of output power . 20
7 Buoyancy change of a target . 20
7.1 General . 20
7.2 Requirements for equipment . 21
7.2.1 Target type . 21
7.2.2 Entry window diameter . 22
7.2.3 Balance / force measuring system . 22
7.2.4 System tank . 22
7.2.5 Target support structures . 22
7.2.6 Transducer positioning . 22
7.2.7 Anti-streaming foils . 22
7.2.8 Transducer coupling . 23
7.2.9 Calibration . 23
7.3 Requirements for measuring conditions . 23
7.3.1 Lateral target position . 23
7.3.2 Transducer/Target separation . 23
7.3.3 Water . 23
7.3.4 Water contact . 24
7.3.5 Environmental conditions . 24
7.3.6 Thermal drifts . 24
7.4 Measurement uncertainty . 24
7.4.1 General . 24
7.4.2 Buoyancy sensitivity . 24
7.4.3 Non-planar ultrasound field . 24
7.4.4 Balance system including target suspension . 24
7.4.5 Linearity and resolution of the balance system . 24
7.4.6 Curve-fitting and extrapolation . 25
7.4.7 Water temperature . 25
7.4.8 Ultrasonic attenuation and acoustic streaming . 25
7.4.9 Foil properties . 25
7.4.10 Finite target size . 25
7.4.11 Environmental influences . 25
7.4.12 Excitation voltage measurement . 25
7.4.13 Ultrasonic transducer temperature . 26
7.4.14 Nonlinearity . 26
7.4.15 Other sources . 26
7.5 Calculation of output power . 26
8 Electrical characteristics . 26
8.1 Electrical impedance . 26
8.2 Radiation conductance . 26
8.3 Efficiency . 27
Annex A (informative) Other measurement methods . 28
Annex B (informative) Target size . 29
Annex C (informative) Formulae for radiation force . 31
Annex D (informative) Expansion method . 36
Annex E (informative) Influence of attenuation and acoustic streaming on determining
incident and output powers . 42

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SIST EN 62555:2014
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Annex F (informative) Avoidance of cavitation . 45
Annex G (informative) Transducer efficiency . 46
Bibliography . 54

Figure 1 – Linearity check: balance readout as a function of the input quantity . 20
Figure C.1 – Correction factor of plane wave for the acoustic field of a circular plane
piston ultrasonic transducer as a function of the product of the circular wavenumber
and transducer radius . 33
Figure D.1 – Schematic diagram of an expansion target. . 36
Figure D.2 – Example of weight vs time sequence . 37
Figure D.3 – Time history of the apparent mass of the castor oil target at different
frequencies following an insonation of approximately 1 W acoustic power for a period
of 10 s . 40
Figure G.1 – Electrical voltage source under different loading conditions . 52
Figure G.2 – Electrical voltage source and electrical matching network and transducer
equivalent circuit . 52
Figure G.3 – Diagram illustrating electrical loss. . 53

Table D.1 – Selected properties of Acros® Organics castor oil in the range 10 °C to
60 °C . 39
Table D.2 – Absorption coefficient of castor oil as a function of temperature . 41

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SIST EN 62555:2014
62555 © IEC:2013 – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________

ULTRASONICS – POWER MEASUREMENT –
HIGH INTENSITY THERAPEUTIC ULTRASOUND (HITU)
TRANSDUCERS AND SYSTEMS

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
in the subject dealt with may participate in this preparatory work. International, governmental and non-
governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely
with the International Organization for Standardization (ISO) in accordance with conditions determined by
agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 62555 has been prepared by IEC technical committee
87: Ultrasonics
The text of this standard is based on the following documents:
FDIS Report on voting
87/538/FDIS 87/543/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.
NOTE The following print types are used:
• Requirements: roman type
• Notes: in small roman type

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SIST EN 62555:2014
– 6 – 62555 © IEC:2013
• Words in bold in the text are defined in Clause 3.
• The numbers in square brackets refer to references given in the Bibliography which follows Annex G.
The committee has decided that the contents of this 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.

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SIST EN 62555:2014
62555 © IEC:2013 – 7 –
INTRODUCTION
In ultrasound fields at megahertz frequencies, output power is typically determined by
measuring the force on a target using a radiation force balance [1],[2],[3]. However, the
relationship between the radiation force and the output power is affected by the focusing or
other geometrical aspects of the field, by the type and shape of the target, by the distance of
the target from the transducer, by absorption (including ‘shock-loss’) in the water path, and by
acoustic streaming currents. Whilst many of these effects are small for typical diagnostic or
physiotherapy ultrasound fields, they cannot generally be ignored for HITU fields (particularly
for those often referred to as high intensity focused ultrasound HIFU) [4]. Furthermore, in
HITU, the quantity of interest is the power incident on the patient rather than the output power
at the transducer face. Since it is common to have a water stand-off between the transducer
and the patient, attenuation and shock-loss in the water path may be significant and will vary
depending upon the chosen distance.
The purpose of this International Standard is to establish standard methods of measurement
of ultrasonic power of HITU devices in liquids in the lower megahertz frequency range based
on the measurement of the radiation force using a gravimetric balance, and calorimetry
(based on the measurement of thermal expansion). This standard identifies the sources of
errors and describes a systematic step-by-step procedure to assess overall measurement
uncertainty as well as the precautions that should be undertaken and uncertainties that should
be taken into account while performing power measurements. Practical guidance is given for
the determination of acoustic power from the very wide range of transducer geometries used
for HITU. Unlike radiation force approaches in IEC 61161 that deal with “time average power,”
other power measurement methods are described in this document.
The structure and content of parts of this International Standard are largely based on
IEC 61161:2013 but there are differences that are summarised below. In this standard the
prime measurand is considered to be the incident power, and not the output power. Output
power is always the quantity of interest in IEC 61161, which specifies that measurements are
made with the target placed close to the transducer. However, this may not always be
possible for strongly convergent transducers and there are cases where it is more relevant to
measure the incident power which reaches a specified surface at some substantial distance
from the transducer (this surface may represent the skin surface of the patient, for instance).
This extra distance may result in significant nonlinear loss in the water path even at low
megahertz frequencies. Consequently, in this International Standard the prime measurand is
considered to be the incident power, and not the output power. The incident power may of
course be the basis for determining the output power using an appropriate model with its own
uncertainties.

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SIST EN 62555:2014
– 8 – 62555 © IEC:2013
ULTRASONICS – POWER MEASUREMENT –
HIGH INTENSITY THERAPEUTIC ULTRASOUND (HITU)
TRANSDUCERS AND SYSTEMS



1 Scope
This International Standard
• establishes general principles relevant to HITU fields for the use of radiation force
balances in which an obstacle (target) intercepts the sound field to be measured;
• specifies a calorimetric method of determining the total emitted acoustic power of
ultrasonic transducers based on the measurement of thermal expansion of a fluid-filled
target;
• specifies requirements related to the statement of electrical power characteristics of
ultrasonic transducers;
• provides guidance related to the avoidance of acoustic cavitation during measurement;
• provides guidance related to the measurement of HITU transducers of different
construction and geometry, including collimated, diverging and convergent transducers,
and multi-element transducers;
• provides guidance on the choice of the most appropriate measurement method;
• provides information on assessment of overall measurement uncertainties.
This International Standard is applicable to the measurement of ultrasonic power generated
by HITU equipment up to 500 W in the frequency range from 0,5 MHz to 5 MHz. HITU
equipment may generate convergent, collimated or divergent fields.
For frequencies less than 500 kHz, no validations exist and the user should assess the
uncertainties of the power measurement and measurement system at the frequencies of
operation.
This International Standard does not apply to:
• ultrasound equipment used for physiotherapy, for lithotripsy for general pain relief.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and
are indispensable for its application. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any
amendments) applies.
IEC 61161:2013, Ultrasonics – Power measurement – Radiation force balances and
performance requirements
IEC/TR 62781, Ultrasonics – Conditioning of water for ultrasonic measurements
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.

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SIST EN 62555:2014
62555 © IEC:2013 – 9 –
3.1
acoustical efficiency
η
a
ratio of the acoustic output power from an ultrasonic transducer to the transducer
electrical power
Note 1 to entry: Acoustical efficiency is unitless.
3.2
acoustic streaming
bulk fluid motion initiated by a sound field
[SOURCE: IEC 61161:2013, 3.1]
3.3
buoyancy sensitivity
S
ratio of the increase in the buoyancy force on an expansion target to the amount of absorbed
energy in the absence of thermal losses
Note 1 to entry: This ratio may be temperature dependent.
Note 2 to entry: The buoyancy sensitivity for a fluid filled expansion target immersed in water is most
conveniently and most accurately determined by calibration using electrical heating (see 7.2.9). It can also be
calculated from the product of the expansion ratio, the density of the water and the acceleration due to gravity
but, in practice, this leads to higher uncertainties.
Note 3 to entry: Since most sensitive balances display weight in grams or millig
...