EN IEC 61846:2025

Ultrasonics - Therapeutic focused short pressure pulse sources - Characteristics of fields

IEC 61846:2025 is applicable to: – therapy equipment using extracorporeally induced focused pressure pulse waves; – therapy equipment producing focused mechanical energy excluding thermal energy. This document does not apply to percutaneous and laser lithotripsy equipment. This document does not apply to: – histotripsy or other therapeutic ultrasound bursts of longer time duration than that of the pressure pulse; – non-focused pressure pulse equipment. This document specifies: – measurable parameters which could be used in the declaration of the acoustic output of extracorporeal focused pressure pulse equipment; – methods of measurement and characterization of the pressure field generated by focused pressure pulse equipment. While this document has been developed for equipment intended for use in lithotripsy, it has been developed such that, as long as no other specific standards are available to be used for other medical applications of therapeutic extracorporeal focused pressure pulse equipment, this document can be used as a guideline. IEC 61846:2025 cancels and replaces the first edition published in 1998. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition: a) Change of title: "pressure pulse lithotripters" in the previous edition is changed to "therapeutic focused short pressure pulse sources" in order to take into account the development in the relevant technical and biomedical applications of such sources, which were originally used only for (kidney) lithotripsy, while recent applications include a wide range for the treatment of, for example, stone diseases, orthopaedic pain, tissue, cardiac and brain diseases. The term "focused" was added to differentiate IEC 61846 from IEC 63045. The term "short" was added to align the nomenclature to IEC 63045 and to differentiate IEC 61846 from standards in the HIFU and HITU fields. b) Clause 1 and elsewhere in the document: The term "lithotripsy" is changed to "therapy" in order to account for the wide range of applications beyond stone diseases. c) Clause 3: The "−6 dB" parameter definitions are replaced by "−n dB" to avoid misconceptions in the significance and use of these parameters and to account for newer findings in literature. Additional "n MPa" parameters are introduced for the same reasons. The definitions of "derived" parameters are aligned to those in recently published standards, for example IEC 62127-1. New definitions were added which describe parameters appearing in newer relevant literature, for example "momentum", "average positive acoustic pressure", "cavitation induction index", "pulse to pulse variability", "total pressure pulse energy dose". d) Clause 6: The terms "focus hydrophone" and "field hydrophone" were removed to account for newer technical developments. New terms distinguish between "hydrophones for pressure pulse measurements" and "hydrophones for quality assurance". e) Annexes: Descriptions, tables and figures were edited to account for newer literature and standards as well as technical developments.

Ultraschall - Therapeutisch fokussierte Kurzdruckimpulsquellen - Feldeigenschaften

Ultrasons - Sources d'impulsions de pression courtes focalisées thérapeutiques - Caractéristiques des champs

L'IEC 61846:2025 s'applique: – aux appareils de traitement qui utilisent des ondes d'impulsions de pression focalisées générées de manière extracorporelle; – aux appareils de traitement qui produisent une énergie mécanique focalisée, à l'exclusion de l'énergie thermique. Le présent document ne s'applique pas aux appareils de lithotritie percutanée et laser. Le présent document ne s'applique pas: – à l'histotripsie ou autres salves d'ultrasons thérapeutiques d'une durée plus longue que celle de l'impulsion de pression; – aux appareils à impulsions de pression non focalisées. Le présent document spécifie: – les paramètres mesurables qui peuvent être utilisés dans la déclaration des émissions acoustiques des appareils à impulsions de pression focalisées générées de manière extracorporelle; – les méthodes de mesure et de caractérisation du champ de pression généré par les appareils à impulsions de pression focalisées. Le présent document a été élaboré pour des appareils destinés à être utilisés en lithotritie. Il peut être utilisé comme ligne directrice pour d'autres applications médicales concernant des appareils thérapeutiques à impulsions de pression focalisées générées de manière extracorporelle, tant qu'aucune autre norme spécifique n'est disponible. L'IEC 61846:2025 annule et remplace la première édition parue en 1998. Cette édition constitue une révision technique. Cette édition inclut les modifications techniques majeures suivantes par rapport à l'édition précédente: a) Modification du titre: Le terme "lithotriteurs à impulsion de pression" utilisé dans l'édition précédente a été modifié en "sources d'impulsions de pression courtes focalisées thérapeutiques" afin de prendre en compte le développement des applications techniques et biomédicales pertinentes de ces types de sources, qui n'étaient à l'origine utilisées que pour la lithotritie (rénale), tandis que les applications récentes couvrent un large éventail de traitements, par exemple, des maladies des calculs, des douleurs orthopédiques, ainsi que des maladies tissulaires, cardiaques et cérébrales. L'adjectif "focalisées" a été ajouté pour distinguer l'IEC 61846 de l'IEC 63045. L'adjectif "courtes" a été ajouté afin d'aligner la nomenclature sur l'IEC 63045 et de distinguer l'IEC 61846 des normes relatives aux champs à ultrasons focalisés de haute intensité (HIFU, High Intensity Focalised Ultrasound) et aux champs à ultrasons thérapeutiques de haute intensité (HITU, High Intensity Therapeutic Ultrasound). b) Article 1 et ailleurs dans le document: Le terme "lithotritie" a été modifié en "thérapie" afin de tenir compte du large éventail d'applications qui dépassent le cadre des maladies des calculs. c) Article 3: Les définitions des paramètres "−6 dB" ont été remplacées par "−n dB" afin d'éviter des malentendus concernant la signification et l'utilisation de ces paramètres, mais également pour refléter les dernières découvertes exposées dans les ouvrages de référence. Des paramètres "n MPa" supplémentaires ont été ajoutés pour les mêmes raisons. Les définitions des paramètres "dérivés" ont été alignées sur celles des normes récemment publiées, par exemple l'IEC 62127-1. De nouvelles définitions ont été ajoutées pour décrire les paramètres qu

Ultrazvok - Terapevtsko usmerjeni viri kratkih tlačnih impulzov - Karakteristike polj (IEC 61846:2025)

Ta dokument se uporablja za:
– terapevtsko opremo, ki uporablja zunajtelesno inducirane usmerjene tlačne impulzne valove; – terapevtsko opremo, ki proizvaja usmerjeno mehansko energijo, razen toplotne energije.
Ta dokument se ne uporablja za opremo za perkutano in lasersko litotripsijo.
Ta dokument se ne uporablja za:
– histotripsijo ali druge terapevtske ultrazvočne sunke, ki trajajo dlje kot tlačni impulz; – opremo za ustvarjanje neusmerjenih tlačnih impulzov.
Ta dokument določa:
– izmerljive parametre, ki bi jih bilo mogoče uporabiti pri navedbi akustičnega izhoda opreme za ustvarjanje zunajtelesnih usmerjenih tlačnih impulzov; – metode merjenja in karakterizacije tlačnega polja, ki ga ustvarja oprema za ustvarjanje usmerjenih tlačnih impulzov.
OPOMBA: Parametri, opredeljeni v tem dokumentu, trenutno ne omogočajo kvantitativnih trditev o učinkovitosti in morebitnih nevarnostih. Še posebej ni mogoče podati natančnih omejitev teh učinkov.
Čeprav je bil ta dokument oblikovan za opremo, namenjeno uporabi pri litotripsiji, ga je mogoče uporabljati kot vodilo tudi za druge medicinske namene v zvezi z uporabo terapevtske opreme za ustvarjanje zunajtelesnih usmerjenih tlačnih impulzov, dokler ne bodo razviti ustrezni specifični standardi.

General Information

• Status: Published
• Publication Date: 13-Mar-2025
• ICS: 11.040.50 - Radiographic equipment
• Technical Committee: CLC/SR 87 - CLC/SR 87
• Drafting Committee: IEC/TC 87 - IEC_TC_87
• Current Stage: 6060 - Document made available - Publishing
• Start Date: 14-Mar-2025
• Due Date: 31-Oct-2024
• Completion Date: 14-Mar-2025
• Ref Project: SIST EN IEC 61846:2025 - Ultrasonics - Therapeutic focused short pressure pulse sources - Characteristics of fields (IEC 61846:2025)

Relations

• Replaces: EN 61846:1998 - Ultrasonics - Pressure pulse lithotripters - Characteristics of fields
• Effective Date: 26-Jan-2023

Standards Content (Sample)

SLOVENSKI STANDARD
01-maj-2025
Ultrazvok - Terapevtsko usmerjeni viri kratkih tlačnih impulzov - Karakteristike polj
(IEC 61846:2025)
Ultrasonics - Therapeutic focused short pressure pulse sources - Characteristics of fields
(IEC 61846:2025)
Ultraschall - Druckpuls-Lithotripter - Feldcharakterisierung (IEC 61846:2025)
Ultrasons - Lithotripteurs à ondes de pression - Caractérisation des champs (IEC
61846:2025)
Ta slovenski standard je istoveten z: EN IEC 61846:2025
ICS:
11.040.50 Radiografska oprema Radiographic equipment
17.140.50 Elektroakustika Electroacoustics
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD EN IEC 61846

NORME EUROPÉENNE
EUROPÄISCHE NORM March 2025
ICS 11.040.50 Supersedes EN 61846:1998
English Version
Ultrasonics - Therapeutic focused short pressure pulse sources -
Characteristics of fields
(IEC 61846:2025)
Ultrasons - Sources d'impulsions de pression courtes Ultraschall - Therapeutisch fokussierte
focalisées thérapeutiques - Caractéristiques des champs Kurzdruckimpulsquellen - Feldeigenschaften
(IEC 61846:2025) (IEC 61846:2025)
This European Standard was approved by CENELEC on 2025-03-06. 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,
Türkiye 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
© 2025 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN IEC 61846:2025 E
European foreword
The text of document 87/879/FDIS, future edition 2 of IEC 61846, prepared by 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) 2026-03-31
level by publication of an identical national standard or by endorsement
• latest date by which the national standards conflicting with the (dow) 2028-03-31
document have to be withdrawn
This document supersedes EN 61846:1998 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 61846:2025 was approved by CENELEC as a European
Standard without any modification.
In the official version, for Bibliography, the following note has to be added for the standard indicated:
IEC 61828:2020 NOTE Approved as EN IEC 61828:2021 (not modified)
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.cencenelec.eu.
Publication Year Title EN/HD Year
IEC 60050-113 2011 International Electrotechnical Vocabulary - - -
Part 113: Physics for electrotechnology
IEC/TR 62781 - Ultrasonics - Conditioning of water for - -
ultrasonic measurements
IEC 60565-1 - Underwater acoustics - Hydrophones - EN IEC 60565-1 -
Calibration of hydrophones - Part 1:
Procedures for free-field calibration of
hydrophones
IEC 60565-2 - Underwater acoustics - Hydrophones - EN IEC 60565-2 -
Calibration of hydrophones - Part 2:
Procedures for low frequency pressure
calibration
IEC 62127-1 2022 Ultrasonics - Hydrophones - Part 1: EN IEC 62127-1 2022
Measurement and characterization of
medical ultrasonic fields
IEC 62127-2 2025 Ultrasonics - Hydrophones - Part 2: EN IEC 62127-2 2025
Calibration for ultrasonic fields
IEC 62127-3 - Ultrasonics - Hydrophones - Part 3: EN IEC 62127-3 -
Properties of hydrophones for ultrasonic
fields
IEC 63045 2020 Ultrasonics - Non-focusing short pressure EN IEC 63045 2020
pulse sources including ballistic pressure
pulse sources - Characteristics of fields

IEC 61846 ®
Edition 2.0 2025-01
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Ultrasonics – Therapeutic focused short pressure pulse sources –

Characteristics of fields
Ultrasons – Sources d'impulsions de pression courtes focalisées thérapeutiques –

Caractéristiques des champs
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 11.040.50  ISBN 978-2-8327-0132-4

– 2 – IEC 61846:2025 © IEC 2025
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 7
2 Normative references . 7
3 Terms and definitions . 8
3.1 Acoustic pulse energy . 8
4 List of symbols . 17
5 Conditions of measurement . 18
6 Test equipment . 18
6.1 Test chamber . 18
6.2 Hydrophone . 18
6.2.1 General . 18
6.2.2 Hydrophone for pressure pulse measurements . 19
6.2.3 Hydrophones for quality assurance . 19
6.3 Voltage measurement . 20
6.3.1 Oscilloscope or transient recorder . 20
6.3.2 Pressure-pulse-waveform recording . 20
7 Measurement procedure . 21
7.1 General . 21
7.2 Spatial measurements . 21
7.2.1 General . 21
7.2.2 Beam plots of peak-compressional acoustic pressure . 21
7.2.3 Beam plots of peak-rarefactional acoustic pressure . 22
7.2.4 Focus position . 22
7.2.5 Focal −n dB width . 22
7.2.6 Focal −n dB extent . 22
7.2.7 Focal −n dB cross sectional area . 22
7.2.8 Focal −n dB volume . 22
7.3 Temporal measurements . 22
7.4 Acoustic energy measurements . 23
7.4.1 Pulse-pressure-squared integral . 23
7.4.2 Derived pulse-intensity integral . 23
7.4.3 Derived focal acoustic pulse energy . 23
7.4.4 Derived acoustic pulse energy . 23
7.4.5 Average positive pressure . 24
7.4.6 Momentum . 24
Annex A (informative) Short pressure pulse therapy. 25
A.1 Background. 25
A.2 Percutaneous continuous wave systems and alternative burst wave
applications . 25
A.3 Exclusions . 25
A.4 Extracorporeally induced lithotripsy . 26
Annex B (informative) Types of pressure wave transducers . 27
B.1 Overview. 27
B.1.1 General . 27
B.1.2 Spark discharge . 27

IEC 61846:2025 © IEC 2025 – 3 –
B.1.3 Piezoelectric . 27
B.1.4 Electromagnetic . 27
B.2 Positioning systems . 28
Annex C (informative) Field measurement . 29
C.1 Measurement probes and hydrophones . 29
C.2 Test chamber . 31
C.3 Degassing procedures . 31
C.4 Acoustic pulse energy . 32
Bibliography . 36

Figure C.1 – Typical measured pressure pulse waveform and parameters at the focus . 33
Figure C.2 – Typical spatial pressure distribution measurements in three orthogonal
coordinates of a focused pressure pulse source . 34
Figure C.3 – Schematic of focusing and focal geometry of a high amplitude pulsed
focused acoustic pressure field produced by an electrohydraulic type shock wave
generator commonly used in ESWT . 35
Figure C.4 – Examples of the different focal regions according to −6 dB and 5 MPa

contour in the focal peak-compressional pressure axial and lateral distribution . 35

Table C.1 – Hydrophones for focus and field measurements . 30
Table C.2 – Measurement techniques and probes for quality assurance purposes . 31

– 4 – IEC 61846:2025 © IEC 2025
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ULTRASONICS – THERAPEUTIC FOCUSED SHORT PRESSURE PULSE
SOURCES – CHARACTERISTICS OF FIELDS

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
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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
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any IEC Publication and the corresponding national or regional publication shall be clearly indicated in the latter.
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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
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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) IEC draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). IEC takes no position concerning the evidence, validity or applicability of any claimed patent rights in
respect thereof. As of the date of publication of this document, IEC had not received notice of (a) patent(s), which
may be required to implement this document. However, implementers are cautioned that this may not represent
the latest information, which may be obtained from the patent database available at https://patents.iec.ch. IEC
shall not be held responsible for identifying any or all such patent rights.
IEC 61846 has been prepared by IEC technical committee 87: Ultrasonics. It is an International
Standard.
This second edition cancels and replaces the first edition published in 1998. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) Change of title:
"pressure pulse lithotripters" in the previous edition is changed to "therapeutic focused short
pressure pulse sources" in order to take into account the development in the relevant
technical and biomedical applications of such sources, which were originally used only for
(kidney) lithotripsy, while recent applications include a wide range for the treatment of, for
example, stone diseases, orthopaedic pain, tissue, cardiac and brain diseases.
The term "focused" was added to differentiate IEC 61846 from IEC 63045.

IEC 61846:2025 © IEC 2025 – 5 –
The term "short" was added to align the nomenclature to IEC 63045 and to differentiate
IEC 61846 from standards in the HIFU and HITU fields.
b) Clause 1 and elsewhere in the document: The term "lithotripsy" is changed to "therapy" in
order to account for the wide range of applications beyond stone diseases.
c) Clause 3: The "−6 dB" parameter definitions are replaced by "−n dB" to avoid
misconceptions in the significance and use of these parameters and to account for newer
findings in literature.
Additional "n MPa" parameters are introduced for the same reasons.
The definitions of "derived" parameters are aligned to those in recently published standards,
for example IEC 62127-1.
New definitions were added which describe parameters appearing in newer relevant
literature, for example "momentum", "average positive acoustic pressure", "cavitation
induction index", "pulse to pulse variability", "total pressure pulse energy dose".
d) Clause 6: The terms "focus hydrophone" and "field hydrophone" were removed to account
for newer technical developments. New terms distinguish between "hydrophones for
pressure pulse measurements" and "hydrophones for quality assurance".
e) Annexes: Descriptions, tables and figures were edited to account for newer literature and
standards as well as technical developments.
The text of this International Standard is based on the following documents:
Draft Report on voting
87/879/FDIS 87/887/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.
Words in bold in the text are defined in Clause 3.
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/publications.
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, or
• revised.
– 6 – IEC 61846:2025 © IEC 2025
INTRODUCTION
Focused short pressure pulses were initially (since February 1980) applied clinically in
lithotripsy, to break up and disrupt calcific deposits within the body, in particular, stones within
the renal, biliary and salivary glands tracts. Extracorporeal pressure pulse lithotripsy has up to
now been regarded as the most applied therapeutic option for treating most renal calculi [18],
[23], [24].
The use of pressure pulses has been evolved to a more general use, often called
"extracorporeal shock wave therapy (ESWT)" which expands its application to a broad range of
musculoskeletal conditions, including plantar fasciitis, calcific tendinitis of the shoulder, lateral
or medial epicondylitis of the elbow, pain treatment, non-union and delayed union of fractures
[25]. Some of these are also treated using unfocused pressure pulse sources, which are
specified in IEC 63045.
Several different forms of equipment for lithotripsy and for ESWT are commercially available
from a number of manufacturers.
This document specifies methods of measuring and characterizing the acoustic pressure field
generated by focusing pressure pulse equipment.

IEC 61846:2025 © IEC 2025 – 7 –
ULTRASONICS – THERAPEUTIC FOCUSED SHORT PRESSURE PULSE
SOURCES – CHARACTERISTICS OF FIELDS

1 Scope
This document is applicable to:
– therapy equipment using extracorporeally induced focused pressure pulse waves;
– therapy equipment producing focused mechanical energy excluding thermal energy.
This document does not apply to percutaneous and laser lithotripsy equipment.
This document does not apply to:
– histotripsy or other therapeutic ultrasound bursts of longer time duration than that of the
pressure pulse;
– non-focused pressure pulse equipment.
This document specifies:
– measurable parameters which could be used in the declaration of the acoustic output of
extracorporeal focused pressure pulse equipment;
– methods of measurement and characterization of the pressure field generated by focused
pressure pulse equipment.
NOTE The parameters defined in this document do not – at the present time – allow quantitative statements to be
made about effectiveness and possible hazard. In particular, it is not possible to make a statement about the limits
for these effects.
While this document has been developed for equipment intended for use in lithotripsy, it has
been developed such that, as long as no other specific standards are available to be used for
other medical applications of therapeutic extracorporeal focused pressure pulse equipment,
this document can be used as a guideline.
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 60050-113:2011, International Electrotechnical Vocabulary – Part. 113: Physics for
electrotechnology,
IEC TR 62781, Ultrasonics – Conditioning water for ultrasonic measurements
IEC 60565-1, Underwater acoustics – Hydrophones – Calibration of hydrophones –Part 1:
Procedures for free field calibration of hydrophones
IEC 60565-2, Underwater acoustics – Hydrophones – Calibration of hydrophones – Part 2:
Procedures for low frequency pressure calibration
IEC 62127-1:2022, Ultrasonics – Hydrophones – Part 1: Measurement and characterization of
medical ultrasonic fields
– 8 – IEC 61846:2025 © IEC 2025
IEC 62127-2:2025, Ultrasonics – Hydrophones – Part 2: Calibration for ultrasonic fields
IEC 62127-3, Ultrasonics – Hydrophones – Part 3: Properties of hydrophones for ultrasonic
fields
IEC 63045:2020, Ultrasonics – Non-focusing short pressure pulse sources including ballistic
pressure pulse sources – Characteristics of fields
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 60050-13 and the
following apply.
ISO and IEC maintain terminology databases for use in standardization at the following
addresses:
• IEC Electropedia: available at https://www.electropedia.org/
• ISO Online browsing platform: available at https://www.iso.org/obp
3.1 Acoustic pulse energy
3.1.1
derived acoustic pulse energy
E
R
spatial integral of the derived pulse-intensity integral over a circular cross-sectional area of
radius R in the x-y plane which contains the focus
Note 1 to entry: The radius R is derived either from the largest size of a threshold value of pressure, derived pulse
intensity integral, or any other quantity. This quantity is stated as a second index. The manufacturer chooses the
appropriate quantity and threshold value based on their clinical significance, based on one or more of clinical
significance, literature and risk analysis.
Note 2 to entry: The derived acoustic pulse energy is expressed in joules (J).
3.1.2
derived focal acoustic pulse energy
E
f
spatial integral of the derived pulse-intensity integral over the focal cross-sectional area
Note 1 to entry: The derived focal acoustic pulse energy is expressed in joules (J).
3.2
beam axis
line passing through the geometric centre of the aperture of the pressure pulse generator and
the focus
Note 1 to entry: This line is taken as the z axis. See 6.1 and Clause 7.
3.3
compressional pulse duration
t
FWHM,pc
time interval beginning at the first time the instantaneous acoustic pressure exceeds 50 %
of the peak-compressional acoustic pressure and ending at the next time the instantaneous
acoustic pressure has that value
SEE: Figure C.1.
Note 1 to entry: The compressional pulse duration is expressed in seconds (s).
Note 2 to entry: The subscript "FWHM" stands for "full width, half maximum".

IEC 61846:2025 © IEC 2025 – 9 –
3.4
rarefactional pulse duration
t
pr
time interval beginning at the first time the instantaneous acoustic pressure is less than 10 %
of the peak-rarefactional acoustic pressure after the decay of the peak-compressional
acoustic pressure and ending at the next time the instantaneous acoustic pressure has that
value
SEE: Figure C.1.
Note 1 to entry: The rarefactional pulse duration is expressed in seconds (s).
3.5
derived pulse-intensity integral
PΠ(x,y,z)
time integral of the instantaneous intensity at a particular point in a pressure pulse field over
the pressure pulse waveform
Note 1 to entry: This parameter is often called "energy flux density".
Note 2 to entry: The derived pulse-intensity integral is expressed in units of joule per metre squared (J/m ).
Note 3 to entry: The temporal limits for the calculation of the derived pulse-intensity integral are specified in the
temporal integration limits definitions.
3.6
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 =
( )
L
 pt()
( )
Note 1 to entry: The end-of-cable loaded sensitivity is a complex-valued parameter. Its modulus is expressed in
−1
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 62127-1:2022, 3.25].
3.7
focal −n dB cross-sectional area
A
f,ndB
area of the peak-compressional acoustic pressure contour which is in the plane,
perpendicular to the beam axis and containing the focus, where all points on the contour have
a pressure of −n dB relative to the value at the focus
Note 1 to entry: The value of n is stated as subscript.
Note 2 to entry: Typical values of −n dB are: −3 dB, −6 dB, −10 dB, −12 dB, −20 dB. Reasonable values of n for
clinical approval and communication to the users can be identified by a risk analysis process, by applicable safety
standards, by consulting notified bodies, expert communities (e.g. ISMST – International Society for Medical
Shockwave Treatment) or through literature.
Note 3 to entry: The focal −n dB cross-sectional area is expressed in units of metre squared (m ).

– 10 – IEC 61846:2025 © IEC 2025
3.8
focal −n dB extent
L
fz,ndB
shortest distance along the z axis that connects points on the contour of peak-compressional
acoustic pressure which have a value of −n dB relative to the acoustic pressure at the focus
Note 1 to entry: The value of n and the axial distance z from the measurement centre point are stated as subscript.
Note 2 to entry: Typical values of −n dB are: −3 dB, −6 dB, −10 dB, −12 dB, −20 dB. Reasonable values of n for
clinical approval and communication to the users can be identified by a risk analysis process, by applicable safety
standards, by consulting notified bodies, expert communities (e.g. ISMST – International Society for Medical
Shockwave Treatment) or through literature.
Note 3 to entry: The focal −n dB extent is expressed in metres (m).
3.9
focal −n dB volume
V
f,ndB
volume in space contained within the surface defined by the −n dB (relative to the focal
pressure maximum value) peak-compressional acoustic pressure contours measured
around the focus
Note 1 to entry: It can be difficult to measure −n dB points throughout the volume around the focus. It is reasonable
in practice to approximate the focal −n dB volume from measurements taken in three orthogonal directions: the
beam axis (z axis); the direction of maximum beam diameter (x axis); the axis perpendicular to the x axis (y axis),
which are also orthogonal to the beam axis.
Note 2 to entry: Typical values of −n dB are: −3 dB, −6 dB, −10 dB, −12 dB, −20 dB. Reasonable values of n for
clinical approval and communication to the users can be identified by a risk analysis process, by applicable safety
standards, by consulting notified bodies, expert communities (e.g. ISMST – International Society for Medical
Shockwave Treatment) or through literature.
Note 3 to entry: The focal −n dB volume is expressed in units of metre cubed (m ).
Note 4 to entry: The value of n is stated as a subscript.
Note 5 to entry: See IEC 61828.
3.10
focal −n dB width, maximum
L
fx,ndB
maximum width of the −n dB (relative to the focal pressure maximum value) contour of p
c
around the focus in the x-y plane which contains the focus
Note 1 to entry: Typical values of −n dB are: −3 dB, −6 dB, −10 dB, −12 dB, −20 dB. Reasonable values of n for
clinical approval and communication to the users can be identified by a risk analysis process, by applicable safety
standards, by consulting notified bodies, expert communities (e.g. ISMST – International Society for Medical
Shockwave Treatment) or through literature.
Note 2 to entry: The focal width, maximum is expressed in metres (m).
3.11
focal −n dB width, orthogonal
L
fy,ndB
width of the −n dB (relative to the focal pressure maximum value) contour of p around the
c
focus, in the x-y plane which contains the focus, in the direction perpendicular to fx
Note 1 to entry: Typical values of −n dB are: −3 dB, −6 dB, −10 dB, −12 dB, −20 dB. Reasonable values of n for
clinical approval and communication to the users can be identified by a risk analysis process, by applicable safety
standards, by consulting notified bodies, expert communities (e.g. ISMST – International Society for Medical
Shockwave Treatment) or through literature.
Note 2 to entry: The focal width, orthogonal is expressed in metres (m).

IEC 61846:2025 © IEC 2025 – 11 –
3.12
focal n MPa cross-sectional area
A
f,nMPa
area of the peak-compressional acoustic pressure contour which is in the plane,
perpendicular to the beam axis and containing the focus, where all points on the contour have
a pressure of n MPa
Note 1 to entry: The value of n is stated as subscript.
Note 2 to entry: a typical values of n is 5 MPa. Reasonable values of n for clinical approval and communication to
the users can be identified by a risk analysis process, by applicable safety standards, by consulting notified bodies,
expert communities (e.g. ISMST – International Society for Medical Shockwave Treatment) or through literature.
Note 3 to entry: The focal n MPa cross-sectional area is expressed in units of metre squared (m ).
3.13
focal n MPa extent
L
fz,nMPa
shortest distance along the z axis that connects points on the contour of peak-compressional
acoustic pressure which have a value of n MPa
Note 1 to entry: The value of n and the axial distance z from the measurement centre point are stated as subscript.
Note 2 to entry: a typical values of n is 5 MPa. Reasonable values of n for clinical approval and communication to
the users can be identified by a risk analysis process, by applicable safety standards, by consulting notified bodies,
expert communities (e.g. ISMST – International Society for Medical Shockwave Treatment) or through literature.
Note 3 to entry: The focal n MPa extent is expressed in metres (m).
3.14
focal n MPa volume
V
f,nMPa
volume in space contained within the surface defined by the −n dB (relative to the focal
pressure maximum value) peak-compressional acoustic pressure contours measured
around the focus
Note 1 to entry: It is reasonable in practice to approximate the focal n MPa volume from measurements taken in
three orthogonal directions: the beam axis (z axis); the direction of maximum beam diameter (x axis); the axis
perpendicular to the x axis (y axis), which are also orthogonal to the beam axis.
Note 2 to entry: A typical values of n is: 5 MPa. Reasonable values of n for clinical approval and communication to
the users can be identified by a risk analysis process, by applicable safety standards, by consulting notified bodies,
expert communities (e.g. ISMST – International Society for Medical Shockwave Treatment) or through literature.
Note 3 to entry: The focal n MPa volume is expressed in units of metre cubed (m ).
Note 4 to entry: The value of n is stated as a subscript.
Note 5 to entry: See IEC 61828 [37].
3.15
focal n MPa width, maximum
L
fx,nMPa
maximum width of the n MPa contour of p around the focus in the x-y plane which contains the
c
focus
Note 1 to entry: A typical values of n is: 5 MPa. Reasonable values of n for clinical approval and communication to
the users can be identified by a risk analysis process, by applicable safety standards, by consulting notified bodies,
expert communities (e.g. ISMST – International Society for Medical Shockwave Treatment) or through literature.
Note 2 to entry: The focal width, maximum is expressed in metres (m)

– 12 – IEC 61846:2025 © IEC 2025
3.16
focal n MPa width, orthogonal
L
fy,nMPa
width of the n MPa contour of p around the focus, in the x-y plane which contains the focus,
c+
in the direction perpendicular to fx
Note 1 to entry: A typical values of n is: 5 MPa. Reasonable values of n for clinical approval and communication to
the users can be identified by a risk analysis process, by applicable safety standards, by consulting notified bodies,
expert communities (e.g. ISMST – International Society for Medical Shockwave Treatment) or through literature.
Note 2 to entry: The focal width, orthogonal is expressed metres (m).
3.17
focus
location in the pressure pulse field of the maximum peak-compressional acoustic pressure
Note 1 to entry: Additional, the geometric focus can be given as point location to which all the pressure pulses are
converged according to ray theory valid as frequency goes to infinite.
3.18
hydrophone
transducer that produces electrical signals in response to pressure fluctuations in water
[SOURCE: IEC 60050-801:2021, 801-32-26, modified – The notes to entry have been removed.]
3.19
instantaneous acoustic pressure
p
pressure minus the ambient pressure at a particular instant in time and at a particular point in
an acoustic field
Note 1 to entry: In order to clarify that this parameter usually varies in time, (t) can be added in the formulae, for
example p(t).
Note 2 to entry: The instantaneous acoustic pressure is expressed in pascals (Pa).
[SOURCE: IEC 60050-802:2011, 802-01-03, modified – The definition has been rephrased, and
the notes to entry added.]
3.20
derived instantaneous intensity
I
quotient of squared instantaneous acoustic pressure and characteristic acoustic impedance
of the medium at a particular instant in time at a particular point in an acoustic field
pt()
It() = (1)
ρc
where
p(t) is the instantaneous acoustic pressure;
ρ is the density of the medium;
c is the speed of sound in the medium
Note 1 to entry: Derived instantaneous intensity is an approximation of the instantaneous intensity.
Note 2 to entry: Derived instantaneous intensity is expressed in units of watt per metre squared (W/m ).

IEC 61846:2025 © IEC 2025 – 13 –
Note 3 to entry: Increased uncertainty is expected to be taken into account for measurements very close to the
transducer.
[SOURCE: IEC 62127-1:2022, 3.14, modified – The notes have been rephrased.]
3.21
lithotripsy equipment
device for disintegrating calculi and other concretions within the body
Note 1 to entry: Known applications include renal stones, gallstones, pancreatic duct stones, salivary stones,
orthopaedic pain and calcification in tendons.
Note 2 to entry: Equipment for other known clinical applications such as pseudoarthrosis, cardiac applications, etc.
can be termed ESWT equipment.
3.22
peak-rarefactional acoustic pressure
p
r
maximum of the modulus of the rarefactional acoustic pressure at any spatial location in the
pressure pulse field
Note 1 to entry: The peak-rarefactional acoustic pressure is expressed in pascals (Pa).
Note 2 to entry: The peak-rarefactional acoustic pressure is also called "peak-negative acoustic pressure".
3.23
peak-compressional acoustic pressure
p
c
maximum compressional acoustic pressure at any spatial location in the pressure pulse field
Note 1 to entry: The peak-compressional acoustic pressure is expressed in pascals (Pa).
Note 2 to entry: The peak-compressional acoustic pressure is also called "peak-positive acoustic pressure".
3.24
average positive acoustic pressure

p
c,AVG
value calculated by averaging the peak-compressional acoustic pressure values over a
circular cross-sectional area of radius R in the x-y plane which contains the focus
Note 1 to entry: The radius R is derived from the typical size of the area to be treated. This can be the typical size
of a target like a kidney stone or a targeted tissue area, or the largest size of a threshold value of pressure, derived
pulse intensity integral, or any other quantity. This quantity is stated as a second index. The manufacturer chooses
the appropriate quantity and threshold value based on their clinical significance, based on literature or risk analysis
or both.
Note 2 to entry: The average positive acoustic pressure is expressed in pascals (Pa).
3.25
momentum
vector quantity equal to the product of the mass m of a body and the velocity v of its centre of
mass
Note 1 to entry: For a continuous body in a domain D, momentum is equal to the integral ρVvvd = d m , where
∫∫
DD
ρ is the mass density in a domain having quasi-infinitesimal volume dV and mass dm, and velocity v. For a system
of bodies, it is equal to the sum of their momentums.
Note 2 to entry: If the sum of external forces is equal to zero, momentum of a body follows a law of conservation.
-1
Note 3 to entry: The coherent SI unit of momentum is kilogram metre per second kg⋅ m⋅ s .
Note 4 to entry: The temporal limits for the calculation of the momentum are specified in the temporal integration
limits definitions.
– 14 – IEC 61846:2025 © IEC 2025
[SOURCE: IEC 60050-113:2001, 113-03-13, modified – The original NOTE 3 is left out, an
additional Note 4 to entry was added, and the symbol p was removed.]
3.26
pressure pulse
acoustic wave emitted by the pressure pulse equipment, which consists of two significant wave
components: one positive or negative half-cycle and one negative or positive trailing half cycle
SEE: Figure C.1.
Note 1 to entry: Pressure pulse sources or combinations of pressure pulse sources emitting signals composed of
two or more pressure pulses which are emitted with pulse-to-pulse intervals longer than the total duration of each
single pressure pulse as specified in the temporal integration limits definitions are characterized by separately
documenting the parameters of each pressure pulse
Note 2 to entry: Depending on the properties of the pressure pulse source, spurious additional signals of smaller
amplitude can follow the significant wave components. Only signal parts adding more than 5 % to the energy content
of the wave are considered as significant. Wave components, which are for example caused by inertial motions of a
mechanical applicator which is specified in IEC 63045, can appear several hundred microseconds to some
milliseconds after the pressure pulse. These signals are outside the scope of this document. See [39] and [40].
Note 3 to entry: Typical applications of pressure pulses are given in Annex A.
3.27
pressure pulse waveform
temporal waveform of the instantaneous acoustic pressure at a specified position in a
pressure pulse field and displayed over a period sufficiently long to include all significant
acoustic information in the pressure pulse
Note 1 to entry: The time durations
...