Ultrasonics - Field characterization - Test methods for the determination of thermal and mechanical indices related to medical diagnostic ultrasonic fields

IEC 62359:2010 is applicable to medical diagnostic ultrasound fields. It establishes: - parameters related to thermal and non-thermal exposure aspects of diagnostic ultrasonic fields; - methods for the determination of an exposure parameter relating to temperature rise in theoretical tissue-equivalent models, resulting from absorption of ultrasound; - methods for the determination of an exposure parameter appropriate to certain non-thermal effects. This second edition cancels and replaces the first edition, published in 2005. It constitutes a technical revision. Major changes with respect to the previous edition include the following: - The methods of determination set out in the first edition of this standard were based on those contained in the American standard for Real-Time Display of Thermal and Mechanical Acoustic Output Indices on Diagnostic Ultrasound Equipment (ODS) and were intended to yield identical results. While this second edition also follows the ODS in principal and uses the same basic formulae and assumptions (see Annex A), it contains a few significant modifications which deviate from the ODS. - One of the primary issues dealt with in preparing this second edition of IEC 62359 was 'missing' TI equations. In Edition 1 there were not enough equations to make complete 'at-surface' and 'below-surface' summations for TIS and TIB in combined-operating modes. Thus major changes with respect to the previous edition are related to the introduction of new calculations of thermal indices to take into account both 'at-surface' and 'below-surface' thermal effects.

Ultraschall - Charakterisierung von Feldern - Prüfverfahren für die Ermittlung des thermischen und des mechanischen Indexes bezogen auf medizinische Ultraschalldiagnostikfelder

Ultrasons – Caractérisation du champ – Méthodes d'essai pour la détermination d'indices thermique et mécanique des champs d'ultrasons utilisés pour le diagnostic médical

La CEI 62359:2010 est applicable aux champs d'ultrasons utilisés pour le diagnostic médical. Elle définit: - des paramètres relatifs aux aspects thermiques et non thermiques des champs ultrasonores de diagnostic; - des méthodes de détermination d'un paramètre d'exposition relatif à l'échauffement dans les modèles théoriques équivalents aux tissus, résultant de l'absorption d'ultrasons; - des méthodes de détermination d'un paramètre d'exposition approprié pour certains effets non thermiques. Cette deuxième édition annule et remplace la première édition publiée en 2005. Elle constitue une révision technique. Les modifications majeures par rapport à l'édition précédente incluent ce qui suit: - Les méthodes de détermination présentées dans la première de la présente norme étaient basées sur celles contenues dans la Norme américaine relative à l'affichage en temps réel des Indices d'émission acoustiques thermique et mécanique des appareils de diagnostics à ultrasons (ODS) et devaient fournir des résultats identiques. Bien que l'édition seconde suive également l'ODS dans le principe et utilise les mêmes formules et hypothèses fondamentales (voir Annexe A), elle comporte quelques modifications significatives s'écartant de l'ODS. - L'une des principales questions traitées lors de l'élaboration de l'édition seconde de la CEI 62359 norme faisait référence aux équations de TI 'manquantes'. Elles n'étaient pas suffisantes dans l'édition 1 afin d'effectuer des sommations 'à la surface' et 'sous la surface' complètes pour TIS et TIB en modes de fonctionnement combinés. Ainsi, les modifications majeures par rapport à l'édition précédente sont liées à l'introduction de nouveaux calculs d'indices thermiques pour prendre en compte les effets thermiques 'à la surface' et 'sous la surface'.

Ultrazvok - Karakterizacija polj - Preskusne metode za ugotavljanje termičnih in mehanskih znakov glede medicinskih diagnostičnih ultrazvočnih polj (IEC 62359:2010)

Ta mednarodni standard velja za medicinska diagnostična ultrazvočna polja. Ta standard vzpostavlja: – parametre, povezane z vidiki toplotne izpostavljenosti ali izpostavljenosti, ki ni toplotna, diagnostičnim ultrazvočnim poljem, – metode za določanje parametrov izpostavljanja, povezanih z dvigom temperature v teoretičnih tkivu enakih modelov, ki nastanejo zaradi vpijanja ultrazvoka, – metode za določanje parametrov izpostavljanja do določenih učinkov, ki niso toplotni.

General Information

Status
Withdrawn
Publication Date
30-Apr-2011
Withdrawal Date
31-Jan-2014
Technical Committee
Drafting Committee
Parallel Committee
Current Stage
6060 - Document made available - Publishing
Start Date
11-Feb-2011
Completion Date
11-Feb-2011

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SLOVENSKI STANDARD
SIST EN 62359:2011
01-april-2011
1DGRPHãþD
SIST EN 62359:2007
8OWUD]YRN.DUDNWHUL]DFLMDSROM3UHVNXVQHPHWRGH]DXJRWDYOMDQMHWHUPLþQLKLQ
PHKDQVNLK]QDNRYJOHGHPHGLFLQVNLKGLDJQRVWLþQLKXOWUD]YRþQLKSROM ,(&


Ultrasonics - Field characterization - Test methods for the determination of thermal and

mechanical indices related to medical diagnostic ultrasonic fields (IEC 62359:2010)

Ultraschall - Charakterisierung von Feldern - Prüfverfahren für die Ermittlung des

thermischen und des mechanischen Indexes bezogen auf medizinische
Ultraschalldiagnostikfelder (IEC 62359:2010)

Ultrasons - Caractérisation du champ - Méthodes d'essai pour la détermination d'indices

thermique et mécanique des champs d'ultrasons utilisés pour le diagnostic médical (CEI

62359:2010)
Ta slovenski standard je istoveten z: EN 62359:2011
ICS:
11.040.55 'LDJQRVWLþQDRSUHPD Diagnostic equipment
SIST EN 62359:2011 en

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------
SIST EN 62359:2011
---------------------- Page: 2 ----------------------
SIST EN 62359:2011
EUROPEAN STANDARD
EN 62359
NORME EUROPÉENNE
February 2011
EUROPÄISCHE NORM
ICS 17.140.50 Supersedes EN 62359:2005
English version
Ultrasonics -
Field characterization -
Test methods for the determination of thermal and mechanical indices
related to medical diagnostic ultrasonic fields
(IEC 62359:2010)
Ultrasons – Caractérisation du champ – Ultraschall -
Méthodes d'essai pour la détermination Charakterisierung von Feldern -
d'indices thermique et mécanique des Prüfverfahren für die Ermittlung des
champs d'ultrasons utilisés pour le thermischen und des mechanischen
diagnostic médical Indexes bezogen auf medizinische
(CEI 62359:2010) Ultraschalldiagnostikfelder
(IEC 62359:2010)

This European Standard was approved by CENELEC on 2011-02-01. 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 Central Secretariat 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 Central Secretariat 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, Romania, Slovakia, Slovenia,

Spain, Sweden, Switzerland and the United Kingdom.
CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
Management Centre: Avenue Marnix 17, B - 1000 Brussels

© 2011 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.

Ref. No. EN 62359:2011 E
---------------------- Page: 3 ----------------------
SIST EN 62359:2011
EN 62359:2011 - 2 -
Foreword

The text of document 87/445/FDIS, future edition 2 of IEC 62359, prepared by IEC TC 87, Ultrasonics,

was submitted to the IEC-CENELEC parallel vote and was approved by CENELEC as EN 62359 on

2011-02-01.
This European Standard supersedes EN 62359:2005.
Major changes with respect to EN 62359:2005 include the following:

– The methods of determination set out in EN 62359:2005 were based on those contained in the

American standard for Real-Time Display of Thermal and Mechanical Acoustic Output Indices on

Diagnostic Ultrasound Equipment (ODS) and were intended to yield identical results. While

EN 62359:2010 also follows the ODS in principal and uses the same basic formulae and assumptions

(see Annex A), it contains a few significant modifications which deviate from the ODS.

– One of the primary issues dealt with in preparing EN 62359:2010 was “missing” TI equations. In

EN 62359:2005 there were not enough equations to make complete “at-surface” and “below-surface”

summations for TIS and TIB in combined-operating modes. Thus major changes with respect to

EN 62359:2005 are related to the introduction of new calculations of thermal indices to take into account

both "at-surface" and "below-surface" thermal effects.
For the specific technical changes involved please see Annex E.

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. CEN and CENELEC shall not be held responsible for identifying any or all such patent

rights.
The following dates were fixed:
– latest date by which the EN has to be implemented
at national level by publication of an identical
national standard or by endorsement (dop) 2011-11-01
– latest date by which the national standards conflicting
with the EN have to be withdrawn (dow) 2014-02-01
Annex ZA has been added by CENELEC.
__________
Endorsement notice

The text of the International Standard IEC 62359:2010 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 61689 NOTE Harmonized as EN 61689.
__________
---------------------- Page: 4 ----------------------
SIST EN 62359:2011
- 3 - EN 62359:2011
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications

The following referenced documents are indispensable for the application of this document. For dated

references, only the edition cited applies. For undated references, the latest edition of the referenced

document (including any amendments) applies.

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 60601-2-37 - Medical electrical equipment - EN 60601-2-37 -
Part 2-37: Particular requirements for the
basic safety and essential performance of
ultrasonic medical diagnostic and monitoring
equipment
IEC 61157 2007 Standard means for the reporting of the EN 61157 2007
acoustic output of medical diagnostic
ultrasonic equipment
IEC 61161 2006 Ultrasonics - Power measurement - Radiation EN 61161 2007
force balances and performance requirements
IEC 61828 2001 Ultrasonics - Focusing transducers - EN 61828 2001
Definitions and measurement methods for the
transmitted fields
IEC 62127-1 2007 Ultrasonics - Hydrophones - EN 62127-1 2007
Part 1: Measurement and characterization of
medical ultrasonic fields up to 40 MHz
IEC 62127-2 2007 Ultrasonics - Hydrophones - EN 62127-2 2007
Part 2: Calibration of hydrophones to be used
in ultrasonic fields up to 40 MHz
IEC 62127-3 2007 Ultrasonics - Hydrophones - EN 62127-3 2007
Part 3: Properties of hydrophones for
ultrasonic fields up to 40 MHz
---------------------- Page: 5 ----------------------
SIST EN 62359:2011
---------------------- Page: 6 ----------------------
SIST EN 62359:2011
IEC 62359
Edition 2.0 2010-10
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Ultrasonics – Field characterization – Test methods for the determination of
thermal and mechanical indices related to medical diagnostic ultrasonic fields
Ultrasons – Caractérisation du champ – Méthodes d'essai pour la détermination
d'indices thermique et mécanique des champs d'ultrasons utilisés pour le
diagnostic médical
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX
ICS 17.140.50 ISBN 978-2-88912-181-6
® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale
---------------------- Page: 7 ----------------------
SIST EN 62359:2011
– 2 – 62359 © IEC:2010
CONTENTS

FOREWORD...........................................................................................................................4

INTRODUCTION.....................................................................................................................6

1 Scope...............................................................................................................................7

2 Normative references .......................................................................................................7

3 Terms and definitions .......................................................................................................8

4 List of symbols ...............................................................................................................21

5 Test methods for determining the mechanical index and the thermal index .....................23

5.1 General .................................................................................................................23

5.2 Determination of mechanical index ........................................................................23

5.2.1 Determination of attenuated peak-rarefactional acoustic pressure .............23

5.2.2 Calculation of mechanical index ................................................................23

5.3 Determination of thermal index – general ..............................................................24

5.4 Determination of thermal index in non-scanning mode...........................................24

5.4.1 Determination of soft tissue thermal index for non-scanning modes ...........24

5.4.2 Determination of bone thermal index, TIB, for non-scanning modes ...........25

5.5 Determination of thermal index in scanning modes ................................................26

5.5.1 Determination of soft tissue thermal index for scanning modes ..................26

5.5.2 Determination of bone thermal index for scanning modes ..........................27

5.6 Calculations for combined-operating mode ............................................................28

5.6.1 Acoustic working frequency .......................................................................28

5.6.2 Thermal index............................................................................................28

5.6.3 Mechanical index.......................................................................................29

5.7 Summary of measured quantities for index determination ......................................29

Annex A (informative) Rationale and derivation of index models .........................................30

Annex B (informative) Guidance notes for measurement of output power in combined

modes, scanning modes and in 1 cm × 1 cm windows...........................................................51

Annex C (informative) The contribution of transducer self-heating to the temperature

rise occurring during ultrasound exposure.............................................................................58

Annex D (informative) Guidance on the interpretation of TI and MI ......................................59

Annex E (informative) Differences from IEC 62359 Edition 1................................................61

Bibliography..........................................................................................................................64

Figure 1 – Schematic diagram of the different planes and lines in an ultrasonic field

(modified from IEC 61828 and IEC 62127-1)........................................................................12

Figure A.1 – Focusing transducer with a f-number of about 7................................................37

Figure A.2 – Strongly focusing transducer with a low f-number of about 1.............................37

Figure A.3 – Focusing transducer (f-number ≈ 10) with severe undulations close to the

transducer ............................................................................................................................38

Figure A.4 – Focusing transducer .........................................................................................44

Figure A.5 – Focusing transducer with smaller aperture than that of Figure A.4 ....................44

Figure A.6 – Focusing transducer with a weak focus near z ................................................45

Figure A.7 – Weakly focusing transducer ..............................................................................45

Figure B.1 – Example of curved linear array in scanning mode .............................................53

Figure B.2 – Suggested 1 cm × 1 cm square-aperture mask..................................................56

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SIST EN 62359:2011
62359 © IEC:2010 – 3 –

Figure B.3 – Suggested orientation of transducer, mask aperture and RFB target.................56

Figure B.4 – Suggested orientation of transducer and 1 cm-square RFB target.....................57

Table 1 – Summary of combination formulae for each of the THERMAL INDEX categories.........28

Table 2 – Summary of the acoustic quantities required for the determination of the

indices ..................................................................................................................................29

Table A.1 – Thermal index categories and models ................................................................36

Table A.2 – Consolidated thermal index formulae .................................................................41

Table E.1 – Summary of differences .....................................................................................63

---------------------- Page: 9 ----------------------
SIST EN 62359:2011
– 4 – 62359 © IEC:2010
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ULTRASONICS –
FIELD CHARACTERIZATION –
TEST METHODS FOR THE DETERMINATION OF THERMAL
AND MECHANICAL INDICES RELATED TO
MEDICAL DIAGNOSTIC ULTRASONIC 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 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 requirements 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 62359 has been prepared by IEC technical committee 87:

Ultrasonics.

This second edition cancels and replaces the first edition, published in 2005. It constitutes a

technical revision.
Major changes with respect to the previous edition include the following:

• The methods of determination set out in the first edition of this standard were based on

those contained in the American standard for Real–Time Display of Thermal and

Mechanical Acoustic Output Indices on Diagnostic Ultrasound Equipment (ODS) and were

intended to yield identical results. While this second edition also follows the ODS in

principal and uses the same basic formulae and assumptions (see Annex A), it contains a

few significant modifications which deviate from the ODS.
---------------------- Page: 10 ----------------------
SIST EN 62359:2011
62359 © IEC:2010 – 5 –

• One of the primary issues dealt with in preparing this second edition of IEC 62359 was

“missing” TI equations. In Edition 1 there were not enough equations to make complete

“at-surface” and “below-surface” summations for TIS and TIB in combined-operating

modes. Thus major changes with respect to the previous edition are related to the

introduction of new calculations of thermal indices to take into account both "at-surface"

and "below-surface" thermal effects.
For the specific technical changes involved please see Annex E.
The text of this standard is based on the following documents:
FDIS Report on voting
87/445/FDIS 87/453/RVD

Full information on the voting for the approval of this standard can be found in the report on

voting indicated in the above table.

This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.

This standard may be used to support the requirements of IEC 60601-2-37.
In this particular standard, the following print types are used:

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

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

– test specifications: in italic type
– words in bold are defined terms in Clause 3

The committee has decided that the contents of this amendment and the base 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.

IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates

that it contains colours which are considered to be useful for the correct

understanding of its contents. Users should therefore print this document using a

colour printer.
---------------------- Page: 11 ----------------------
SIST EN 62359:2011
– 6 – 62359 © IEC:2010
INTRODUCTION

Medical diagnostic ultrasonic equipment is widely used in clinical practice for imaging and

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

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

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

current clinical practice.

The ultrasound entering the patient interacts with the patient's tissue, and this interaction can

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

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

indices that can be used to help in assessing the hazard caused by exposure to a particular

ultrasonic field used for medical diagnosis or monitoring. It is recognised that these indices

have limitations, and knowledge of the indices at the time of an examination is not sufficient in

itself to make an informed clinical risk assessment. It is intended that these limitations will be

addressed in future revisions of this standard and as scientific understanding increases. While

such increases remain pending, several organizations have published prudent-use
statements.

Under certain conditions specified in IEC 60601-2-37, these indices are displayed on medical

ultrasonic equipment intended for these purposes.
---------------------- Page: 12 ----------------------
SIST EN 62359:2011
62359 © IEC:2010 – 7 –
ULTRASONICS –
FIELD CHARACTERIZATION –
TEST METHODS FOR THE DETERMINATION OF THERMAL
AND MECHANICAL INDICES RELATED TO
MEDICAL DIAGNOSTIC ULTRASONIC FIELDS
1 Scope

This International standard is applicable to medical diagnostic ultrasound fields.

This standard establishes

– parameters related to thermal and non-thermal exposure aspects of diagnostic ultrasonic

fields;

– methods for the determination of an exposure parameter relating to temperature rise in

theoretical tissue-equivalent models, resulting from absorption of ultrasound;

– methods for the determination of an exposure parameter appropriate to certain non-

thermal effects.

NOTE 1 In Clause 3 of this standard, SI units are used (per ISO/IEC Directives, Part 2, ed. 5, Annex I b) in the

Notes below definitions of certain parameters, such as beam areas and intensities; it may be convenient to use

decimal multiples or submultiples in practice. Users must take care of decimal prefixes used in combination with

the units when using and calculating numerical data. For example, beam area may be specified in cm and

2 2
intensities in W/cm or mW/cm .

NOTE 2 Underlying calculations have been done from 0,25 MHz to 15 MHz for MI and 0,5 MHz to 15 MHz for TI.

NOTE 3 The thermal indices are steady state estimates based on the acoustic output power required to produce

-1 -1

a 1°C temperature rise in tissue conforming to the “homogeneous tissue 0,3 dBcm MHz attenuation model” [1 ]

and may not be appropriate for radiation force imaging, or similar techniques that employ pulses or pulse bursts of

sufficient duration to create a significant transient temperature rise. [2]
2 Normative references

The following referenced documents are indispensable for the application of this document.

For dated references, only the edition cited applies. For undated references, the latest edition

of the referenced document (including any amendments) applies.

IEC 60601-2-37, Medical electrical equipment – Part 2-37: Particular requirements for the

basic safety and essential performance of ultrasonic medical diagnostic and monitoring

equipment

IEC 61157:2007, Standard means for the reporting of the acoustic output of medical

diagnostic ultrasonic equipment
IEC 61161:2006, Ultrasonics – Power measurement – Radiation force balances and
performance requirements

IEC 61828:2001, Ultrasonics – Focusing transducers – Definitions and measurement methods

for the transmitted fields

IEC 62127-1:2007, Ultrasonics – Hydrophones – Part 1: Measurement and characterization of

medical ultrasonic fields up to 40 MHz
___________
Figures in square brackets refer to Bibliography.
---------------------- Page: 13 ----------------------
SIST EN 62359:2011
– 8 – 62359 © IEC:2010

IEC 62127-2:2007, Ultrasonics – Hydrophones – Part 2: Calibration for ultrasonic fields up to

40 MHz

IEC 62127-3:2007, Ultrasonics – Hydrophones – Part 3: Properties of hydrophones for

ultrasonic fields up to 40 MHz
3 Terms and definitions

For the purposes of this document, the terms and definitions given in IEC 62127-1:2007,

IEC 62127-2:2007, IEC 62127-3:2007, IEC 61157:2007 and IEC 61161:2006 (several of which

are repeated below for convenience) apply.

NOTE Units below definitions are given is SI units as per ISO/IEC Directives, Part 2, ed. 5, Annex I b). Users

must be alert to possible need to convert units when using this standard in situations where data are received in

units that are different from those used in the SI system.
3.1
acoustic attenuation coefficient

coefficient intended to account for ultrasonic attenuation of tissue between the external

transducer aperture and a specified point
NOTE 1 A linear dependence on frequency is assumed.
-1 1

NOTE 2 Acoustic attenuation coefficient is expressed in neper per metre per hertz (Np m Hz ).

3.2
acoustic absorption coefficient

coefficient intended to account for ultrasonic absorption of tissue in the region of interest

NOTE 1 A linear dependence on frequency is assumed.
-1 1

NOTE 2 Acoustic absorption coefficient is expressed in decibels per metre per hertz (dB m Hz ).

3.3
acoustic repetition period
arp

time interval between corresponding points of consecutive cycles for continuous wave

systems

NOTE 1 The acoustic repetition period is equal to the pulse repetition period for non-automatic scanning

systems and to the scan repetition period for automatic scanning systems.
NOTE 2 The acoustic repetition period is expressed in seconds (s).
[IEC 62127-1:2007, definition 3.2, modified]
3.4
acoustic working frequency

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 The signal is analysed using either the zero-crossing acoustic-working frequency technique or a

spectrum analysis method. Specific acoustic-working frequencies are defined in 3.4.1 and 3.4.2.

NOTE 2 For pulsed waveforms the acoustic-working frequency shall be measured at the position of maximum

pulse-pressure-squared integral.
NOTE 3 Acoustic frequency is expressed in hertz (Hz).
[IEC 62127-1:2007, definition 3.3, modified]
---------------------- Page: 14 ----------------------
SIST EN 62359:2011
62359 © IEC:2010 – 9 –
3.4.1
zero-crossing acoustic-working frequency
awf

number 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 Any half-cycle in which the waveform shows evidence of phase change shall not be counted.

NOTE 2 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 This frequency is determined according to the procedure specified in IEC/TR 60854 [3].

NOTE 4 This frequency is intended for continuous-wave systems only.
3.4.2
arithmetic-mean acoustic-working frequency
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 This frequency is intended for pulse-wave systems only.
NOTE 2 It is assumed that f < f .
1 2
3.5
attenuated bounded-square output power
P (z)
1x1,α
The maximum value of the attenuated output power passing through any one square
centimeter of the plane perpendicular to the beam axis at depth z

NOTE 1 At z = 0 (the transducer surface) P (z) becomes the bounded-square output power, that is, at z = 0,

1x1,α
P = P .
1x1,α 1x1
NOTE 2 Attenuated bounded-square output power is expressed in watts (W).
3.6
attenuated output power
P (z)

value of the acoustic output power after attenuation, at a specified distance from the

external transducer aperture, and given by
(-α z f /10dB)
awf
P (z) = P 10 (1)
where
α is the acoustic attenuation coefficient;

z is the distance from the external transducer aperture to the point of interest;

f is the acoustic working frequency;
awf
P is the output power measured in water.
NOTE 1 Attenuated output power is expressed in watts (W).

NOTE 2 In the case of stand-offs the P should represent the output power emanating from the stand-off.

3.7
attenuated peak-rarefactional acoustic pressure
p (z)
r,α

value of the peak-rarefactional acoustic pressure after attenuation, at a specified distance

from the external transducer aperture, and given by
---------------------- Page: 15 ----------------------
SIST EN 62359:2011
– 10 – 62359 © IEC:2010
(-α z f /20dB)
awf
p (z) = p ()z 10 (2)
r ,α r
where
α is the acoustic attenuation
...

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