SIST EN IEC 61689:2022

SLOVENSKI STANDARD
01-junij-2022
Nadomešča:
SIST EN 61689:2013
Ultrazvok - Fizioterapevtski sistemi - Specifikacije polja in merilne metode v
frekvenčnem območju od 0,5 MHz do 5 MHz (IEC 61689:2022)
Ultrasonics - Physiotherapy systems - Field specifications and methods of measurement
in the frequency range 0,5 MHz to 5 MHz (IEC 61689:2022)
Ultraschall - Physiotherapiesysteme - Feldspezifikation und Messverfahren im
Frequenzbereich von 0,5 MHz bis 5 MHz (IEC 61689:2022)
Ultrasons - Systèmes de physiothérapie - Spécifications des champs et méthodes de
mesure dans la gamme de fréquences de 0,5 MHz à 5 MHz (IEC 61689:2022)
Ta slovenski standard je istoveten z: EN IEC 61689:2022
ICS:
11.040.60 Terapevtska oprema Therapy equipment
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD EN IEC 61689

NORME EUROPÉENNE
EUROPÄISCHE NORM April 2022
ICS 11.040.60 Supersedes EN 61689:2013
English Version
Ultrasonics - Physiotherapy systems - Field specifications and
methods of measurement in the frequency range 0,5 MHz to 5
MHz
(IEC 61689:2022)
Ultrasons - Systèmes de physiothérapie - Spécifications Ultraschall - Physiotherapiesysteme - Feldspezifikation und
des champs et méthodes de mesure dans la plage de Messverfahren im Frequenzbereich von 0,5 MHz bis 5 MHz
fréquences de 0,5 MHz à 5 MHz (IEC 61689:2022)
(IEC 61689:2022)
This European Standard was approved by CENELEC on 2022-04-12. CENELEC members are bound to comply with the CEN/CENELEC
Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.
Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC
Management Centre or to any CENELEC member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CENELEC member into its own language and notified to the CEN-CENELEC Management Centre has the
same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic,
Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the
Netherlands, Norway, Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.

European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2022 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN IEC 61689:2022 E
European foreword
The text of document 87/784/FDIS, future edition 4 of IEC 61689, prepared by IEC/TC 87 "Ultrasonics"
was submitted to the IEC-CENELEC parallel vote and approved by CENELEC as
The following dates are fixed:
• latest date by which the document has to be implemented at national (dop) 2023-01-12
level by publication of an identical national standard or by endorsement
• latest date by which the national standards conflicting with the (dow) 2025-04-12
document have to be withdrawn
This document supersedes EN 61689:2013 and all of its amendments and corrigenda (if any).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CENELEC shall not be held responsible for identifying any or all such patent rights.
Any feedback and questions on this document should be directed to the users’ national committee. A
complete listing of these bodies can be found on the CENELEC website.
Endorsement notice
The text of the International Standard IEC 61689:2022 was approved by CENELEC as a European
Standard without any modification.
In the official version, for Bibliography, the following notes have to be added for the standards
indicated:
IEC 61828 NOTE Harmonized as EN IEC 61828
IEC 62127-2 NOTE Harmonized as EN 62127-2
IEC 62127-3 NOTE Harmonized as EN 62127-3
IEC 62555 NOTE Harmonized as EN 62555
IEC 63009 NOTE Harmonized as EN IEC 63009
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments)
applies.
NOTE 1  Where an International Publication has been modified by common modifications, indicated by (mod),
the relevant EN/HD applies.
NOTE 2  Up-to-date information on the latest versions of the European Standards listed in this annex is available
here: www.cenelec.eu.
Publication Year Title EN/HD Year
IEC 60601-1 - Medical electrical equipment - Part 1: General EN 60601-1 -
requirements for basic safety and essential
performance
IEC 60601-2-5 - Medical electrical equipment - Part 2-5: EN 60601-2-5 -
Particular requirements for the basic safety
and essential performance of ultrasonic
physiotherapy equipment
IEC 61161 - Ultrasonics - Power measurement - Radiation EN 61161 -
force balances and performance requirements
IEC 62127-1 - Ultrasonics - Hydrophones - Part 1: - -
Measurement and characterization of medical
ultrasonic fields
IEC 61689 ®
Edition 4.0 2022-03
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Ultrasonics – Physiotherapy systems – Field specifications and methods

of measurement in the frequency range 0,5 MHz to 5 MHz

Ultrasons – Systèmes de physiothérapie – Spécifications des champs

et méthodes de mesure dans la plage de fréquences de 0,5 MHz à 5 MHz

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 11.040.60 ISBN 978-2-8322-1080-0

– 2 – IEC 61689:2022 © IEC 2022
CONTENTS
FOREWORD . 5
INTRODUCTION . 7
1 Scope . 8
2 Normative references . 8
3 Terms and definitions . 9
4 Symbols . 18
5 Ultrasonic field specifications . 19
6 Conditions of measurement and test equipment used . 20
6.1 General . 20
6.2 Test vessel . 20
6.3 Hydrophone . 21
6.4 RMS peak signal measurement . 22
7 Type testing reference procedures and measurements . 22
7.1 General . 22
7.2 Rated output power . 23
7.3 Hydrophone measurements . 23
7.4 Effective radiating area . 24
7.4.1 Effective radiating area measurements . 24
7.4.2 Hydrophone positioning . 24
7.4.3 Beam cross-sectional area determination . 24
7.4.4 Active area gradient determination . 24
7.4.5 Beam type determination . 25
7.4.6 Effective radiating area calculation . 25
7.4.7 Beam non-uniformity ratio calculation . 25
7.4.8 Testing requirements . 25
7.5 Reference type testing parameters. 26
7.6 Acceptance criteria for reference type testing . 26
8 Routine measurement procedure . 27
8.1 General . 27
8.2 Rated output power . 27
8.3 Effective radiating area . 27
8.4 Beam non-uniformity ratio . 27
8.5 Effective intensity. 28
8.6 Acceptance criteria for routine testing . 28
9 Sampling and uncertainty determination . 28
9.1 Reference type testing measurements . 28
9.2 Routine measurements . 28
9.3 Uncertainty determination . 29
Annex A (normative) Guidance for performance and safety . 30
A.1 General . 30
A.2 Rated output power . 30
A.3 Effective intensity. 30
A.4 Beam non-uniformity ratio . 30
A.4.1 General . 30

IEC 61689:2022 © IEC 2022 – 3 –
A.4.2 Rationale behind using a limiting value for the beam non-uniformity ratio
(R ) . 30
BN
Annex B (normative) Raster scan measurement and analysis procedures . 35
B.1 General . 35
B.2 Requirements for raster scans . 35
B.3 Requirements for analysis of raster scan data . 36
B.3.1 General . 36
B.3.2 Total mean square acoustic pressure . 36
B.3.3 Calculation of the beam cross-sectional area, A . 36
BCS
Annex C (normative) Diametrical or line scan measurement and analysis procedures . 37
C.1 General . 37
C.2 Requirements for line scans . 37
C.3 Analysis of scans . 37
Annex D (informative) Rationale concerning the beam cross-sectional area definition . 41
Annex E (informative) Factor used to convert the beam cross-sectional area (A ) at
BCS
the face of the treatment head to the effective radiating area (A ) . 42
ER
Annex F (informative) Determining acoustic power through radiation force
measurements . 44
Annex G (informative) Validity of low-power measurements of the beam cross-
sectional area (A ) . 46
BCS
Annex H (informative) Influence of hydrophone effective diameter . 47
Annex I (informative) Effective radiating area measurements using a radiation force
balance and absorbing apertures . 49
I.1 General . 49
I.2 Concept of aperture method . 49
I.3 Requirements for the aperture method . 50
I.3.1 Radiation force balance . 50
I.3.2 Apertures . 50
I.4 Measurement procedure for determining the effective radiating area . 51
I.5 Analysis of raw data to derive the effective radiating area . 52
I.6 Implementation of the aperture technique . 58
I.7 Relationship of results to reference testing method . 59
Annex J (informative) Guidance on uncertainty determination . 60
Annex K (informative) Examples of pulse duration and pulse repetition period of
amplitude modulated waves . 62
Bibliography . 64

Figure A.1 – Normalized, time-averaged values of acoustic intensity (solid line) and of
one of its plane-wave approximations (broken line), existing on the axis of a circular
piston source of ka = 30, plotted against the normalized distance s , where s = λz/a . 33
n n
Figure A.2 – Histogram of R values for 37 treatment heads of various diameters and
BN
frequencies . 34
Figure E.1 – Conversion factor F as a function of the ka product for ka product
ac
between 40 and 160 . 43
Figure I.1 – Schematic representation of aperture measurement set-up . 50
Figure I.2 – Measured power as a function of aperture diameter for commercially
available 1 MHz physiotherapy treatment heads . 54

– 4 – IEC 61689:2022 © IEC 2022
Figure I.3 – Cumulative sum of annular power contributions, previously sorted in
descending order of intensity contributions, plotted against the cumulative sum of their
respective annular areas . 58
Figure K.1 – Example 1: Tone-burst (i.e. rectangular modulation waveform) . 62
Figure K.2 – Example 2: Half-wave modulation with no filtering of the AC mains voltage. 62
Figure K.3 – Example 3: Full-wave modulation with no filtering of the AC mains voltage . 62
Figure K.4 – Example 4: Half-wave modulation with filtering of the AC mains voltage;
filtering insufficient to define the wave as continuous wave (3.17) . 63
Figure K.5 – Example 5: Full-wave modulation with filtering of the AC mains voltage;
filtering insufficient to define the wave as continuous wave (3.17) . 63

Table C.1 – Constitution of the transformed array [B] used for the analysis of half-line
scans . 39
Table F.1 – Necessary target size, expressed as the minimum target radius b, as a
function of the ultrasonic frequency, f, the effective radius of the treatment head, a ,
and the target distance, z, calculated in accordance with A.5.3.1 of IEC 61161:2013
(see [8]) . 45
Table G.1 – Variation of the beam cross-sectional area A (z) with the indicated
BCS
output power from two transducers . 46
Table H.1 – Comparison of measurements of the beam cross-sectional area A (z)
BCS
made using hydrophones of geometrical active element radii 0,3 mm, 0,5 mm and
2,0 mm . 48
Table I.1 – Aperture measurement check sheet . 53
Table I.2 – Annular power contributions . 55
Table I.3 – Annular intensity contributions. 55
Table I.4 – Annular intensity contributions, sorted in descending order . 56
Table I.5 – Annular power contributions, sorted in descending order of intensity
contribution . 56
Table I.6 – Cumulative sum of annular power contributions, previously sorted in
descending order of intensity contribution, and the cumulative sum of their respective
annular areas . 57

IEC 61689:2022 © IEC 2022 – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ULTRASONICS – PHYSIOTHERAPY SYSTEMS –
FIELD SPECIFICATIONS AND METHODS OF MEASUREMENT
IN THE FREQUENCY RANGE 0,5 MHz TO 5 MHz

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,
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preparation is entrusted to technical committees; any IEC National Committee interested in the subject dealt with
may participate in this preparatory work. International, governmental and non-governmental organizations liaising
with the IEC also participate in this preparation. IEC collaborates closely with the International Organization for
Standardization (ISO) in accordance with conditions determined by agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence between
any IEC Publication and the corresponding national or regional publication shall be clearly indicated in the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of patent
rights. IEC shall not be held responsible for identifying any or all such patent rights.
IEC 61689 has been prepared by IEC technical committee 87: Ultrasonics. It is an International
Standard.
This fourth edition cancels and replaces the third edition published in 2013. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition.
a) The requirement on water oxygen content is specified in 6.1.
b) Former recommendations in 6.2 have been changed to become requirements.
c) Several definitions in Clause 3 have been updated in line with other TC 87 documents.
d) The formerly informative Annex A has been changed to become normative, and now
contains details on how conformance with IEC 60601-2-5 requirements is checked.
e) Annex D has been considerably shortened and reference to a now withdrawn regulatory
document has been removed.
– 6 – IEC 61689:2022 © IEC 2022
The text of this International Standard is based on the following documents:
Draft Report on voting
87/784/FDIS 87/789/RVD
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this International Standard is English.
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/standardsdev/publications.
NOTE The following print types are used:
• Requirements: in Arial 10 point
• Notes: in Arial 8 point
• Words in bold in the text are defined in Clause 3
• Symbols and formulae: Times New Roman + Italic
• Compliance clauses: in Arial Italic
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under webstore.iec.ch in the data related to the
specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
IEC 61689:2022 © IEC 2022 – 7 –
INTRODUCTION
Ultrasound at low megahertz frequencies is widely used in medicine for the purposes of
physiotherapy. Such equipment consists of a generator of high frequency electrical energy
and usually a hand-held treatment head, often referred to as an applicator. The treatment
head contains a transducer, usually a disc of piezoelectric material, for converting the electrical
energy to ultrasound and is often designed for contact with the human body.

– 8 – IEC 61689:2022 © IEC 2022
ULTRASONICS – PHYSIOTHERAPY SYSTEMS –
FIELD SPECIFICATIONS AND METHODS OF MEASUREMENT
IN THE FREQUENCY RANGE 0,5 MHz TO 5 MHz

1 Scope
This document is applicable to ultrasonic equipment designed for physiotherapy containing an
ultrasonic transducer generating continuous or quasi-continuous (e.g. tone burst) wave
ultrasound in the frequency range 0,5 MHz to 5 MHz. This document only relates to ultrasonic
physiotherapy equipment employing a single plane non-focusing circular transducer per
treatment head, producing static beams perpendicular to the face of the treatment head.
This document specifies:
• methods of measurement and characterization of the output of ultrasonic physiotherapy
equipment based on reference testing methods;
• characteristics to be specified by manufacturers of ultrasonic physiotherapy equipment
based on reference testing methods;
• guidelines for safety of the ultrasonic field generated by ultrasonic physiotherapy
equipment;
• methods of measurement and characterization of the output of ultrasonic physiotherapy
equipment based on routine testing methods;
• acceptance criteria for aspects of the output of ultrasonic physiotherapy equipment
based on routine testing methods.
Therapeutic value and methods of use of ultrasonic physiotherapy equipment are not within
the scope of this document.
Ultrasonic physiotherapy equipment using ultrasound in the frequency range from 20 kHz
to 500 kHz is dealt with in IEC 63009.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies.
For undated references, the latest edition of the referenced document (including any
amendments) applies.
IEC 60601-1, Medical electrical equipment – Part 1: General requirements for basic safety and
essential performance
IEC 60601-2-5, Medical electrical equipment – Part 2-5: Particular requirements for the basic
safety and essential performance of ultrasonic physiotherapy equipment
IEC 61161, Ultrasonics – Power measurement – Radiation force balances and performance
requirements
IEC 62127-1, Ultrasonics – Hydrophones – Part 1: Measurement and characterization of
medical ultrasonic fields
IEC 61689:2022 © IEC 2022 – 9 –
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1
absolute maximum rated output power
sum of the rated output power, the 95 % confidence overall uncertainty in the rated output
power, and the maximum increase in the rated output power for a ±10 % variation in the rated
value of the mains voltage
Note 1 to entry: The possibility of variation in the rated output power resulting from ±10 % variation in the rated
value of the mains voltage should be checked by using a variable output transformer between the mains voltage
supply and the ultrasonic physiotherapy equipment. See Clause A.2 for further guidance.
Note 2 to entry: Absolute maximum rated output power is expressed in watts (W).
3.2
active area coefficient
Q
quotient of the active area gradient, m, and the beam cross-sectional area at 0,3 cm from
the face of the treatment head, A (0,3 cm)
BCS
−1
Note 1 to entry: Active area coefficient is expressed in units of one per metre (m ).
3.3
active area gradient
m
ratio of the difference of the beam cross-sectional area at z , A (z ), and the beam cross-
N BCS N
sectional area at 0,3 cm from the face of the treatment head, A (0,3 cm), divided by the
BCS
difference of the respective distances
A zA− 0,3 cm
( ) ( )
BCS N BCS
m= (1)
z − 0,3 cm
N
where
A is the beam cross-sectional area;
BCS
z is the distance from the face of the treatment head to the last maximum of the RMS
N
acoustic pressure on the beam alignment axis
Note 1 to entry: Active area gradient is expressed in metres (m).
[SOURCE: IEC 61689:2013, 3.3, modified – The calculation scheme of the gradient was added
to the definition, and the formula was added.]
3.4
absolute maximum beam non-uniformity ratio
beam non-uniformity ratio plus the 95 % confidence overall uncertainty in the beam non-
uniformity ratio
– 10 – IEC 61689:2022 © IEC 2022
3.5
absolute maximum effective intensity
value of the effective intensity corresponding to the absolute maximum rated output power
and the absolute minimum effective radiating area from the equipment
3.6
absolute minimum effective radiating area
effective radiating area minus the 95 % confidence overall uncertainty in the effective
radiating area
3.7
acoustic-working frequency
acoustic frequency
f
awf
frequency of an acoustic signal based on the observation of the output of a hydrophone placed
in an acoustic field at the position corresponding to the spatial-peak temporal-peak acoustic
pressure
Note 1 to entry: The signal is analysed using either the zero-crossing acoustic-working frequency technique or
a spectrum analysis method. Acoustic-working frequencies are defined in 3.7.1 and 3.7.2.
Note 2 to entry: In a number of cases the present definition is not very helpful or convenient, especially for
broadband transducers. In that case a full description of the frequency spectrum should be given in order to enable
any frequency-dependent correction to the signal.
Note 3 to entry: Acoustic frequency is expressed in hertz (Hz).
[SOURCE: IEC 62127-1:2007, 3.3]
3.7.1
arithmetic-mean acoustic-working frequency
f
awf
arithmetic mean of the most widely separated frequencies f and f , within the range of three
1 2
times f , at which the magnitude of the acoustic pressure spectrum is 3 dB below the peak
magnitude
Note 1 to entry: This frequency definition usually is intended for systems that produce short pulses containing only
a few cycles, but it could be used for tone bursts.
Note 2 to entry: It is assumed that f < f .
1 2
Note 3 to entry: If f is not found within the range < 3f , f is to be understood as the lowest frequency above this
2 1 2
range at which the spectrum magnitude is 3 dB below the peak magnitude.
[SOURCE: IEC 62127-1:2007 and IEC 62127-1:2007/AMD1:2013, 3.3.2, modified – Note 1 to
entry has been modified.]
3.7.2
zero-crossing acoustic-working frequency
f
awf
number, n, of consecutive half-cycles (irrespective of polarity) divided by twice the time between
the commencement of the first half-cycle and the end of the n-th half-cycle
Note 1 to entry: None of the n consecutive half-cycles should show evidence of phase change.
Note 2 to entry: The measurement should be performed at terminals in the receiver that are as close as possible to
the receiving transducer (hydrophone) and, in all cases, before rectification.
Note 3 to entry: This frequency is determined in accordance with the procedure specified in IEC TR 60854.
Note 4 to entry: This frequency is intended for continuous wave or quasi-continuous-wave (e.g. tone-burst)
systems only.
IEC 61689:2022 © IEC 2022 – 11 –
[SOURCE: IEC 62127-1:2007/AMD1:2013, 3.3.1, modified – In Note 4 to entry, "or quasi-
continuous-wave (e.g. tone-burst)" has been added.]
3.8
acoustic pulse waveform
temporal waveform of the instantaneous acoustic pressure at a specified position in an
acoustic field and displayed over a period sufficiently long to include all significant acoustic
information in a single pulse or tone-burst, or one or more cycles in a continuous wave
Note 1 to entry: Temporal waveform is a representation (e.g. oscilloscope presentation or equation) of the
instantaneous acoustic pressure.
[SOURCE: IEC 62127-1:2007 and IEC 62127-1:2007/AMD1:2013, 3.1]
3.9
acoustic repetition period
arp
pulse repetition period equal to the time interval between corresponding points of consecutive
cycles for continuous wave systems
Note 1 to entry: Acoustic repetition period is expressed in seconds (s).
[SOURCE: IEC 62127-1:2007, 3.2, modified – The definition has been made more specific for
non-scanning systems.]
3.10
amplitude modulated wave
wave in which the ratio p /(√2p ) at any point in the far field on the beam alignment axis
tp RMS
is greater than 1,05, where p is the temporal-peak acoustic pressure and p is the RMS
tp RMS
acoustic pressure
3.11
attachment head
accessory intended to be attached to the treatment head for the purpose of modifying the
ultrasonic beam characteristics
[SOURCE: IEC 60601-2-5:2009, 201-3-202]
3.12
beam alignment axis
straight line joining two points of maximum RMS acoustic pressure on two plane surfaces
parallel to the faces of the treatment head at specific distances
Note 1 to entry: One plane is at a distance of approximately a /λ where a is the geometrical radius of the active
2 2
element of the treatment head. The second plane surface is at a distance of either 2a /λ or a /(3λ), whichever is the
more appropriate. For the purposes of alignment, this line may be projected to the face of the treatment head.
Note 2 to entry: As the beam alignment axis is used purely for the purposes of alignment, the definitions of specific
distances may be relaxed slightly to reflect the constraints of the measurement system employed. For example, some
treatment heads will have a /λ considerably greater than 12 cm, in which case a maximum distance of 12 cm may
be used to define the first plane. General guidelines for determining the beam alignment axis are given in 7.3.

– 12 – IEC 61689:2022 © IEC 2022
3.13
beam cross-sectional area
A
BCS
minimum area in a specified plane perpendicular to the beam alignment axis for which the
sum of the mean square acoustic pressure is 75 % of the total mean square acoustic
pressure
Note 1 to entry: Beam cross-sectional area is expressed in units of square metre (m ).
Note 2 to entry: The rationale supporting the definition is described in Annex D.
3.14
beam maximum intensity
product of the beam non-uniformity ratio and effective intensity
Note 1 to entry: Beam maximum intensity is expressed in units of watt per square metre (W/m ).
3.15
beam non-uniformity ratio
R
BN
ratio of the square of the maximum RMS acoustic pressure to the spatial average of the
square of the RMS acoustic pressure, where the spatial average is taken over the effective
radiating area
pA
max,RMS ER
R = (2)
BN
pms A
t 0
where
p is the maximum RMS acoustic pressure;
max,RMS
is the effective radiating area;
A
ER
pms is the total mean square acoustic pressure;
t
A is the unit area for the raster scan.
3.16
beam type
descriptive classification of the ultrasonic beam
Note 1 to entry: There are three beam types: collimated (3.18), convergent (3.19) and divergent (3.20).
3.17
continuous wave
wave in which the ratio p /(√2 p ), at any point in the far field on the beam alignment axis,
tp RMS
is less than or equal to 1,05, where p is the temporal-peak acoustic pressure and p is
tp RMS
the RMS acoustic pressure
3.18
collimated
having an active area coefficient, Q, that obeys the following inequality
−1 −1
−0,05 cm ≤ Q ≤ 0,1 cm
IEC 61689:2022 © IEC 2022 – 13 –
3.19
convergent
having an active area coefficient, Q, that obeys the following inequality
−1
Q < −0,05 cm
3.20
divergent
having an active area coefficient, Q, that obeys the following inequality
−1
Q > 0,1 cm
3.21
duty factor
ratio of the pulse duration to the pulse repetition period
3.22
effective intensity
I
e
intensity given by I = P/A where P is the output power and A is the effective radiating
e ER ER
area
Note 1 to entry: Effective intensity is expressed in units of watt per square metre (W/m ).
3.23
effective radiating area
A
ER
beam cross-sectional area determined at a distance of 0,3 cm from the front of the treatment
head, A (0,3 cm), multiplied by a dimensionless factor F equal to 1,333
BCS ac
Note 1 to entry: The conversion factor F is used here in order to derive the area close to the treatment head
ac
which contains 100 % of the total mean square acoustic pressure. The origin of the value of F is described in
ac
Annex E.
Note 2 to entry: Effective radiating area is expressed in units of square metre (m ).
3.24
end-of-cable loaded sensitivity
M (f)
L
quotient of the Fourier transformed hydrophone
voltage-time signal (u (t)) at the end of any integral cable or output connector of a
L
hydrophone or hydrophone assembly, when connected to a specified electric load impedance,
to the Fourier transformed acoustic pulse waveform (p(t)) in the undisturbed free field of a
plane wave in the position of the reference centre of the hydrophone if the hydrophone were
removed
 ut()
( )
L
Mf( )=
(3)
L
 pt
( ())
Note 1 to entry: The end-of-cable loaded sensitivity is a complex-valued parameter. Its modulus is expressed in
units of volt per pascal (V/Pa), its phase angle is expressed in degrees, and represents the phase difference between
the electrical voltage and the sound pressure.
[SOURCE: IEC 61828:2020, 3.50]

– 14 – IEC 61689:2022 © IEC 2022
3.25
far field
region of the field where z > z aligned along the beam axis for planar non-focusing transducers
T
where z is the distance from the face of the treatment head to a specified point on the beam
alignment axis
Note 1 to entry: In the far field, the sound pressure appears to be spherically divergent from a point on or near
the radiating surface. Hence the pressure produced by the sound source is approximately inversely proportional to
the distance from the source.
Note 2 to entry: The term "far field" is used in this document only in connection with non-focusing source
transducers. For focusing transducers a different terminology for the various parts of the transmitted field applies
(see IEC 61828).
Note 3 to entry: For the purposes of this document, the far field starts at a distance where z = A /(πλ), where
T ERN
A is the nominal value of the effective radiating area of the treatment head and λ is the wavelength of the
ERN
ultrasound corresponding to the acoustic working frequency.
[SOURCE: IEC 62127-1:2007/AMD1:2013, 3.28, modified – In the definition, specification of z
has been added and Note 3 to entry has been replaced to provide specific information on z ]
T
3.26
hydrophone
transducer that produces electrical signals in response to pressure fluctuations in water
Note 1 to entry: A hydrophone is principally a passive device designed and built to respond to sound pressure.
Note 2 to entry: In some applications, a hydrophone is used as an active device to transmit sound.
[SOURCE: IEC 60050-801:2021, 801-32-26]
3.27
instantaneous acoustic pressure
p(t)
pressure at a particular instant in time and at a particular point in an acoustic field, minus the
ambient pressure
Note 1 to entry: Instantaneous acoustic pressure is expressed in pascals (Pa).
[SOURCE: IEC 60050-802:2011, 802-01-03]
3.28
maximum RMS acoustic pressure
p
max,RMS
maximum value over the entire acoustic field of the RMS acoustic pressure
Note 1 to entry: Maximum RMS acoustic pressure is expressed in pascals (Pa).
3.29
mean square acoustic pressure
mean square of the instantaneous acoustic pressure at a particular point in the acoustic field,
taken over an integral number of acoustic repetition periods
Note 1 to entry: In practice, the mean value is often derived from RMS measurements.
Note 2 to entry: Mean square acoustic pressure is expressed in units of pascal squared (Pa ).

IEC 61689:2022 © IEC 2022 – 15 –
3.30
modulation waveform
temporal envelope waveform of the amplitude modulated wave at the point of peak RMS
acoustic pressure on the beam alignment axis and displayed over a period sufficiently long
to include all significant acoustic information in the amplitude modulated wave
Note 1 to entry: See Annex K for examples.
3.31
output power
P
time-average ultrasonic power emitted by a treatment head of ultrasonic physiotherapy
equipment into an approximately free field under specified conditions in a specified medium,
preferably in water
Note 1 to entry: Output power is expressed in watts (W).
[SOURCE: IEC 61161:2013, 3.3, modified – In the definition, "ultrasonic transducer" has been
replaced by "treatment head of ultrasonic physiotherapy equipment".]
3.32
peak RMS acoustic pressure
maximum value of the RMS acoustic pressure over a specified region, line or plane in an
acoustic field
Note 1 to entry: Peak RMS acoustic pressure is expressed in pa
...