SIST EN 60601-2-37:2008/A1:2015

Medical electrical equipment - Part 2-37: Particular requirements for the basic safety and essential performance of ultrasonic medical diagnostic and monitoring equipment

Medizinische elektrische Geräte - Teil 2-37: Besondere Festlegungen für die Sicherheit einschließlich der wesentlichen Leistungsmerkmale von Ultraschallgeräten für die medizinische Diagnose und Überwachung

Appareils électromédicaux - Partie 2-37: Exigences particulières pour la sécurité de base et les performances essentielles des appareils de diagnostic et de surveillance médicaux à ultrasons

Medicinska električna oprema - 2-37. del: Posebne zahteve za osnovno varnost in bistvene lastnosti ultrazvočne medicinske diagnostične in nadzorovalne opreme - Dopolnilo A1

General Information

• Status: Published
• Publication Date: 09-Nov-2015
• ICS: 11.040.55 - Diagnostic equipment
• Technical Committee: IEMO - Electrical equipment in medical practice
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 01-Sep-2015
• Due Date: 06-Nov-2015
• Completion Date: 10-Nov-2015
• Directive: 93/42/EEC - Council Directive 93/42/EEC of 14 June 1993 concerning medical devices
• Mandate: M/432 - Standardisation Mandate addressed to CEN and CENELEC within the framework of Directive 2007/47/EC amending Directive 90/385/EEC and Directive 93/42/EEC relating to Medical Devices
• Ref Project: EN 60601-2-37:2008/A1:2015 - Medical electrical equipment - Part 2-37: Particular requirements for the basic safety and essential performance of ultrasonic medical diagnostic and monitoring equipment

Relations

• Replaced By: SIST EN IEC 60601-2-37:2025 - Medical electrical equipment - Part 2-37: Particular requirements for the basic safety and essential performance of ultrasonic medical diagnostic and monitoring equipment (IEC 60601-2-37:2024)
• Effective Date: 01-Jan-2025
• Amends: SIST EN 60601-2-37:2008 - Medical electrical equipment -- Part 2-37: Particular requirements for the basic safety and essential performance of ultrasonic medical diagnostic and monitoring equipment
• Effective Date: 01-Dec-2015

Overview

EN 60601-2-37:2008/A1:2015 (adopted from IEC 60601-2-37:2007/A1:2015) is the European particular standard that specifies basic safety and essential performance requirements for ultrasonic medical diagnostic and monitoring equipment. Published as an amendment in 2015 by CENELEC, it updates the 2008 edition to align with maintenance changes to the general medical electrical safety standard (IEC 60601-1) and to incorporate field-characterization and measurement practice references. The standard is intended to be used alongside the general standard EN/IEC 60601-1 and supports compliance with applicable EU directives.

Key Topics and Requirements

This amendment concentrates on technical and editorial updates; major topics covered include:

• Safety and essential performance requirements specific to ultrasonic diagnostic and monitoring equipment, to be applied in conjunction with EN/IEC 60601-1.
• Terminology and definitions: clarified and added definitions (e.g., Thermal Index (TI), Bone Thermal Index (TIB), Cranial-Bone Thermal Index (TIC), Soft Tissue Thermal Index (TIS), Prudent Use Statement, Transducer Assembly, Ultrasonic Transducer).
• Acoustic exposure metrics and measurement concepts, including new/updated terms such as Attenuated Pulse-Average Intensity, Pulse-Intensity Integral, Depth for Peak metrics (e.g., z_pii), Mechanical Index depth, and Number of Pulses per Ultrasonic Scan Line.
• Normative measurement references: formal linkage to hydrophone and field-characterization standards (notably IEC 62127-1 for hydrophones and IEC 62359 for ultrasonic field characterization and thermal/mechanical indices).
• Editorial and alignment changes to reflect amendments in the parent standard IEC 60601-1 and collateral standards (ensuring consistency in test methods, symbols and units).

Practical Applications and Users

EN 60601-2-37:2008/A1:2015 is used by:

• Ultrasound equipment manufacturers - to design, test and document safety and acoustic performance for diagnostic and monitoring systems.
• Test laboratories and conformity assessment bodies - to perform hydrophone and field-characterization measurements referenced by the standard.
• Regulatory and compliance teams - to demonstrate conformity with European medical device requirements and relevant EU Directives (see informative Annex ZZ).
• Clinical engineers and procurement officers - to evaluate device safety characteristics and performance claims, particularly regarding thermal and mechanical indices.
• Standards writers and R&D teams - when developing product specifications, safety labels and user instructions (e.g., prudent use statements).

Related Standards

Key normative and related standards referenced include:

• IEC/EN 60601-1 (general requirements for basic safety and essential performance)
• IEC 62127-1 (hydrophones - measurement of medical ultrasonic fields)
• IEC 62359 (ultrasonic field characterization - test methods for thermal and mechanical indices)
• IEC 60601-2-18 (endoscopic equipment) - where applicable for ultrasound endoscopes

By combining EN 60601-2-37:2008/A1:2015 with these references, stakeholders can establish robust, measurement-based compliance for ultrasonic medical diagnostic and monitoring equipment.

Standards Content (Sample)

SLOVENSKI STANDARD
01-december-2015
0HGLFLQVNDHOHNWULþQDRSUHPDGHO3RVHEQH]DKWHYH]DRVQRYQRYDUQRVWLQ
ELVWYHQHODVWQRVWLXOWUD]YRþQHPHGLFLQVNHGLDJQRVWLþQHLQQDG]RURYDOQHRSUHPH
'RSROQLOR$
Medical electrical equipment - Part 2-37: Particular requirements for the basic safety and
essential performance of ultrasonic medical diagnostic and monitoring equipment
Medizinische elektrische Geräte - Teil 2-37: Besondere Festlegungen für die Sicherheit
einschließlich der wesentlichen Leistungsmerkmale von Ultraschallgeräten für die
medizinische Diagnose und Überwachung
Appareils électromédicaux - Partie 2-37: Exigences particulières pour la sécurité de base
et les performances essentielles des appareils de diagnostic et de surveillance médicaux
à ultrasons
Ta slovenski standard je istoveten z: EN 60601-2-37:2008/A1:2015
ICS:
11.040.55 'LDJQRVWLþQDRSUHPD Diagnostic equipment
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD EN 60601-2-37:2008/A1

NORME EUROPÉENNE
EUROPÄISCHE NORM
August 2015
ICS 11.040.55; 17.140.50
English Version
Medical electrical equipment - Part 2-37: Particular requirements
for the basic safety and essential performance of ultrasonic
medical diagnostic and monitoring equipment
(IEC 60601-2-37:2007/A1:2015)
Appareils électromédicaux - Partie 2-37: Exigences Medizinische elektrische Geräte - Teil 2-37: Besondere
particulières pour la sécurité de base et les performances Festlegungen für die Sicherheit einschließlich der
essentielles des appareils de diagnostic et de surveillance wesentlichen Leistungsmerkmale von Ultraschallgeräten für
médicaux à ultrasons die medizinische Diagnose und Überwachung
(IEC 60601-2-37:2007/A1:2015) (IEC 60601-2-37:2007/A1:2015)
This amendment A1 modifies the European Standard EN 60601-2-37:2008; it was approved by CENELEC on 2015-07-13. CENELEC
members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this amendment 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 amendment exists in three official versions (English, French, German). A version in any other language made by translation under the
responsibility of a CENELEC member into its own language and notified to the CEN-CENELEC Management Centre has the same status as
the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic,
Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.

European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2015 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN 60601-2-37:2008/A1:2015 E

European foreword
The text of document 62B/978/FDIS, future IEC 60601-2-37:2008/A1, prepared by SC 62B "Diagnostic
imaging equipment" of IEC/TC 62 "Electrical equipment in medical practice" was submitted to the
IEC-CENELEC parallel vote and approved by CENELEC as EN 60601-2-37:2008/A1:2015.

The following dates are fixed:
(dop) 2016-04-13
• latest date by which the document has to be
implemented at national level by
publication of an identical national
standard or by endorsement
• latest date by which the national (dow) 2018-07-13
standards conflicting with the
document have to be withdrawn
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CENELEC [and/or CEN] shall not be held responsible for identifying any or all such
patent rights.
This document has been prepared under a mandate given to CENELEC by the European Commission
and the European Free Trade Association, and supports essential requirements of EU Directive.

For the relationship with EU Directive 93/42/EEC, see informative Annex ZZ, included in EN 60601-2-
37:2008/A11:2011.
Endorsement notice
The text of the International Standard IEC 60601-2-37:2007/A1:2015 was approved by CENELEC as
a European Standard without any modification.
In the Bibliography of EN 60601-2-37:2008, the following note has to be added for the standard
indicated:
IEC 61157:2007 NOTE Harmonized as EN 61157:2007.
IEC 60601-1-11:2015 NOTE Harmonized as EN 60601-1-11:2015.
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
NOTE 1 When 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.
Addition:
Publication Year Title EN/HD Year
IEC 60601-1 2005 Medical electrical equipment -- Part 1: EN 60601-1 2006
General requirements for basic safety and
essential performance
- -  + corrigendum Mar. 2010
+ A1 2012  + A1 2013
- -  + A12 2014
IEC 60601-2-18 2009 Medical electrical equipment -- Part 2-18: - -
Particular requirements for basic safety and
essential performance of endoscopic
equipment
IEC 62127-1 2007 Ultrasonics - Hydrophones -- Part 1: EN 62127-1 2007
Measurement and characterization of
medical ultrasonic fields up to 40 MHz
+ A1 2013  + A1 2013
IEC 62359 2010 Ultrasonics - Field characterization - Test EN 62359 2011
methods for the determination of thermal
and mechanical indices related to medical
diagnostic ultrasonic fields
IEC 60601-2-37 ®
Edition 2.0 2015-06
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
A MENDMENT 1
AM ENDEMENT 1
Medical electrical equipment –

Part 2-37: Particular requirements for the basic safety and essential performance

of ultrasonic medical diagnostic and monitoring equipment

Appareils électromédicaux –
Partie 2-37: Exigences particulières pour la sécurité de base et les performances

essentielles des appareils de diagnostic et de surveillance médicaux à ultrasons

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 11.040.55; 17.140.50 ISBN 978-2-8322-2699-5

– 2 – IEC 60601-2-37:2007/AMD1:2015
© IEC 2015
FOREWORD
This amendment has been prepared by subcommittee 62B: Diagnostic imaging equipment, of
IEC technical committee 62: Electrical equipment in medical practice.
The text of this amendment is based on the following documents:
FDIS Report on voting
62B/978/FDIS 62B/988/RVD
Full information on the voting for the approval of this amendment can be found in the report
on voting indicated in the above table.
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.
_____________
INTRODUCTION TO AMENDMENT 1
The second edition of IEC 60601-2-37 was published in 2007. Since that publication, the
parent standard, IEC 60601-1:2005, entered maintenance, under which an amendment
(IEC 60601-1:2005/AMD1:2012) and a consolidated edition 3.1 (IEC 60601-1:2005 and
IEC 60601-1:2005/AMD1:2012) were published. This amendment to IEC 60601-2-37:2007
addresses three issues:
1) technical changes proposed by National Committees as a result of 4 years of practical
usage,
2) technical and editorial changes resulting from the amended general standard
IEC 60601-1:2005 and IEC 60601-1:2005/AMD1:2012 and its collateral standards
IEC 60601-1-xx, and
3) technical changes as a result of maintenance to normative references.

IEC 60601-2-37:2007/AMD1:2015 – 3 –
© IEC 2015
201.1.1 *Scope
Replace “Addition:” with “Replacement:”
201.2 Normative references
Replace the existing text of this subclause by the following:
Clause 2 of the general standard applies except as follows:
Addition:
IEC 60601-1:2005, Medical electrical equipment – Part 1: General requirements for basic
safety and essential performance
IEC 60601-1:2005/AMD1:2012
IEC 60601-2-18:2009, Medical electrical equipment – Part 2-18: Particular requirements for
the basic safety and essential performance of endoscopic equipment
IEC 62127-1:2007, Ultrasonics – Hydrophones – Part 1: Measurement and characterization of
medical ultrasonic fields up to 40 MHz
IEC 62127-1:2007/AMD1:2013
IEC 62359:2010, Ultrasonics – Field characterization – Test methods for the determination of
thermal and mechanical indices related to medical diagnostic ultrasonic fields
201.3 Terminology and definitions
Replace the existing title of this clause with the following:
201.3 Terms and definitions
201.3.201
Replace the existing text of the term and definition by the following:
BONE THERMAL INDEX
TIB
THERMAL INDEX for applications such as foetal (second and third trimester), in which the
ultrasound beam passes through soft tissue and a focal region is in the immediate vicinity of
bone
Unit: None
[SOURCE: IEC 62359:2010, 3.17, modified – The definition no longer refers to neonatal
cephalic applications, and the original notes have been deleted]
_____________
There exists a consolidated edition (3.1) including IEC 60601-1:2005 and its Amendment 1 (2012).
There exists a consolidated edition (1.1) including IEC 62127-1:2007 and its Amendment 1 (2013).

– 4 – IEC 60601-2-37:2007/AMD1:2015
© IEC 2015
201.3.203
Replace the existing text of the term and definition by the following:
CRANIAL-BONE THERMAL INDEX
TIC
THERMAL INDEX for applications in which the ultrasound beam passes through bone near the
beam entrance into the body, such as paediatric and adult cranial or neonatal cephalic
applications
Unit: None
[SOURCE: IEC 62359:2010, 3.21, modified – The definition now includes a reference to
neonatal cephalic applications, and the original notes have been deleted.]
201.3.211
PRUDENT USE STATEMENT
Replace the existing text of the definition by the following:
affirmation of the principle that only necessary clinical information should be acquired and
that high exposure levels and long exposure times should be avoided
[SOURCE: IEC 62359:2010, 3.40, modified – The definition has been reworded.]
201.3.213
Replace the existing text of the term and definition by the following:
SOFT TISSUE THERMAL INDEX
TIS
THERMAL INDEX related to soft tissues
Unit: None.
[SOURCE: IEC 62359:2010, 3.52, modified – The original notes have been deleted.]
201.3.214
Replace the existing text of the term and definition by the following:
THERMAL INDEX
TI
ratio of ATTENUATED OUTPUT POWER at a specified point to the ATTENUATED OUTPUT POWER
required to raise the temperature at that point in a specific tissue model by 1 °C
Unit: None
[SOURCE: IEC 62359:2010, 3.56, modified – The term "ATTENUATED ACOUSTIC POWER" has
been replaced twice by the term "ATTENUATED OUTPUT POWER", and the original note has been
deleted.]
201.3.215
TRANSDUCER ASSEMBLY
Replace the existing text of the definition by the following:
those parts of ULTRASONIC DIAGNOSTIC EQUIPMENT comprising the ULTRASONIC TRANSDUCER
and/or ULTRASONIC TRANSDUCER ELEMENT GROUP, together with any integral components, such
as an acoustic lens or integral stand-off
Note 1 to entry: The TRANSDUCER ASSEMBLY is usually separable from the ultrasound instrument console.

IEC 60601-2-37:2007/AMD1:2015 – 5 –
© IEC 2015
[SOURCE: IEC 62127-1:2007, 3.69, modified – the original term "medical diagnostic
ultrasound equipment" has been replaced by "ULTRASONIC DIAGNOSTIC EQUIPMENT" in the
definition.]
201.3.216
TRANSMIT PATTERN
Add, at the end of the term and definition, the following source reference:
[SOURCE: IEC 62359:2010, 3.58]
201.3.218
ULTRASONIC TRANSDUCER
Replace the existing text of the term and definition by the following:
device capable of converting electrical energy to mechanical energy within the ultrasonic
frequency range and/or reciprocally of converting mechanical energy to electrical energy
[SOURCE: IEC 62127-1:2007/AMD1:2013, 3.73]
Add the following new definitions:
201.3.219
ATTENUATED PULSE-AVERAGE INTENSITY
I
pa,a
value of the acoustic PULSE-AVERAGE INTENSITY after attenuation and at a specified point, and
given by
(−azf /10 dB)
awf
I = I (z)10
pa,a pa
where
a is the ACOUSTIC ATTENUATION COEFFICIENT as defined in IEC 62359:2010, definition 3.1;
z is the distance from the EXTERNAL TRANSDUCER APERTURE to the point of interest;
f is the ACOUSTIC WORKING FREQUENCY as defined in IEC 62359:2010, definition 3.4;
awf
I (z) is the PULSE-AVERAGE INTENSITY measured in water as defined in IEC 62127-1:2007
pa
and IEC 62127-1:2007/AMD1:2013, definition 3.47.
–2
Unit: W m
201.3.220
NUMBER OF PULSES PER ULTRASONIC SCAN LINE
the number of acoustic pulses travelling along a particular ULTRASONIC SCAN LINE
Note 1 to entry: Here ULTRASONIC SCAN LINE refers to the path of acoustic pulses on a particular BEAM AXIS in
SCANNING and NON-SCANNING MODES.
Note 2 to entry: This number can be used in the calculation of any ultrasound temporal average value from
HYDROPHONE measurements.
Note 3 to entry: The following shows an example of the NUMBER OF PULSES PER ULTRASONIC SCAN LINE and the
NUMBER OF ULTRASONIC SCAN LINES (“;” indicates the end of a frame):
1 2 3 4; 1 2 3 4; 1 2 3 4… n =1; n = 4
pps sl
1 1 2 2 3 3 4 4; 1 1 2 2 3 3 4 4; … n =2; n = 4
pps sl
1 1 1 1 2 2 2 2 3 3 3 3 4 4 4 4; 1 1 1 1 2 2 2 2 3 3 3 3 4 4 4 4; … n = 4; n = 4
pps sl
1 1 2 2 3 3 4 4 1 1 1 2 2 2 3 3 3 4 4 4; 1 1 2 2 3 3 4 4 1 1 1 2 2 2 3 3 3 4 4 4; … n = 5; n = 4 (within one frame
pps sl
the pulses down each line may not occur contiguously).

– 6 – IEC 60601-2-37:2007/AMD1:2015
© IEC 2015
Within one frame, all scan lines may not have the same n value. An example is: 1 2 2 3 3 4; 1 2 2 3 3 4; … avg
pps
n =1,5; max n = 2; n = 4
pps pps sl
[SOURCE: IEC 61157: 2007/AMD1:2013, 3.45, modified – The fourth example in the Note 3 to
entry has been corrected.]
201.3.221
ULTRASOUND ENDOSCOPE
ENDOSCOPE with built-in ULTRASOUND TRANSDUCERS.
201.3.222
ENDOSCOPE
medical instrument having viewing means, with or without optics, introduced into a body
cavity through a natural or surgically created body opening for examination, diagnosis or
therapy
Note 1 to entry: ENDOSCOPES may be of rigid, flexible or capsule type, each of which may have different image
pick-up systems (e.g. via lenses or electronic/ultrasonic sensors) and different image transmission systems (e.g.
optical (via lenses or fibre bundles), or electrical/electronic).
Note 2 to entry: Note 1 to entry differs from NOTE 1 of definition 3.1 in ISO 8600-1 in order to include 'capsule'
endoscopes.
[SOURCE: IEC 60601-2-18:2009, 201.3.203]
201.3.223
DEPTH FOR PEAK PULSE-INTENSITY INTEGRAL
z
pii
position of maximum SPATIAL-PEAK TEMPORAL-AVERAGE INTENSITY for NON-SCANNING MODE
components, determined beyond the BREAK-POINT DEPTH, z , on the BEAM-AXIS
bp
201.3.224
DEPTH FOR PEAK ATTENUATED PULSE-INTENSITY INTEGRAL
z
pii, a
position of maximum ATTENUATED SPATIAL-PEAK TEMPORAL-AVERAGE INTENSITY for NON-
SCANNING MODE components, determined beyond the BREAK-POINT DEPTH, z , on the BEAM-
bp
AXIS
Unit: m
Note 1 to entry: BEAM-AXIS and BREAK-POINT DEPTH are defined in IEC 62359.
201.3.225
DEPTH FOR PEAK SUM OF PULSE-INTENSITY INTEGRALS
z
sii
position of maximum SPATIAL-PEAK TEMPORAL-AVERAGE INTENSITY for SCANNING MODE
components, determined beyond the BREAK-POINT DEPTH, z , on the BEAM-AXIS
bp
Unit: m
Note 1 to entry: BEAM-AXIS and BREAK-POINT DEPTH are defined in IEC 62359.
Note 2 to entry: The subscript ‘sii’ indicates the scan intensity integral (sii). The sii for SCANNING MODE
components at a particular point is determined from the sum over a complete scan frame of the PULSE-INTENSITY
INTEGRALS of the ULTRASONIC SCAN LINES that make up the scanning components of a combined mode. Non-
scanned components are excluded from the sum. See IEC 62359 and IEC 62127-1 for more details.
201.3.226
DEPTH FOR PEAK SUM OF ATTENUATED PULSE-INTENSITY INTEGRALS
z
sii,α
position of maximum ATTENUATED SPATIAL-PEAK TEMPORAL-AVERAGE INTENSITY for SCANNING
MODE components, determined beyond the BREAK-POINT DEPTH, z , on THE BEAM-AXIS
bp
Unit: m
IEC 60601-2-37:2007/AMD1:2015 – 7 –
© IEC 2015
Note 1 to entry: BEAM-AXIS and BREAK-POINT DEPTH are defined in IEC 62359.
Note 2 to entry: The subscript “sii” indicates the “Scan Intensity Integral” that is the sum at a particular point of
the PULSE-INTENSITY INTEGRALS of the ULTRASONIC SCAN LINES comprising a SCANNING MODE component. See
IEC 62359 and IEC 62127-1 for additional details.
201.3.227
DEPTH FOR MECHANICAL INDEX
z
MI
depth on the BEAM-AXIS from the EXTERNAL TRANSDUCER APERTURE to the plane of maximum
ATTENUATED PULSE INTENSITY INTEGRAL (pii )
a
Unit: m
[SOURCE: IEC 62359:2010, 3.23]
Replace the existing table by the following:
Table 201.101 – List of symbols
Symbol Term Reference
A = –12 dB OUTPUT BEAM AREA IEC 62359
aprt
d = EQUIVALENT BEAM DIAMETER IEC 62359
eq
f = ACOUSTIC WORKING FREQUENCY IEC 62359
awf
I = ATTENUATED PULSE-AVERAGE INTENSITY
pa,a
pii = PULSE-INTENSITY INTEGRAL IEC 62359
pii = ATTENUATED PULSE-INTENSITY INTEGRAL IEC 62359
a
I = ATTENUATED SPATIAL-PEAK PULSE-AVERAGE INTENSITY
sppa,a
I = SPATIAL-PEAK, TEMPORAL-AVERAGE INTENSITY IEC 62359
spta
I = ATTENUATED SPATIAL-PEAK TEMPORAL-AVERAGE INTENSITY IEC 62359
spta,a
I (z) = ATTENUATED TEMPORAL-AVERAGE INTENSITY IEC 62359
ta,a
MI = MECHANICAL INDEX IEC 62359
P = OUTPUT POWER IEC 62359
P = ATTENUATED OUTPUT POWER IEC 62359

a
p = ATTENUATED PEAK-RAREFACTIONAL ACOUSTIC PRESSURE IEC 62359
r,a
p = PEAK-RAREFACTIONAL ACOUSTIC PRESSURE IEC 62359
r
n = NUMBER OF PULSES PER ULTRASONIC SCAN LINE IEC 61157
pps
prr = PULSE REPETITION RATE IEC 62359
srr = SCAN REPETITION RATE IEC 62127-1
TI = THERM
...