Ultrasonics - Output test - Guidance for the maintenance of ultrasound physiotherapy systems

IEC TS 62462:2017(E) describes methods meant to assist users of ultrasound physiotherapy systems in checking the performance of such systems. It is applicable primarily to physiotherapists, general medical practitioners, chiropractors, osteopaths, beauty therapists, sports professionals, biomedical engineers, medical physicists, medical device service agents, commercial testers, test houses or manufacturers. This new edition includes the following significant technical change with respect to the previous edition: it includes a novel method for periodic testing regarding possible changes of the effective radiating area using thermochromic absorbers in a new Annex E.

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Status
Published
Publication Date
25-Jul-2017
Technical Committee
Current Stage
PPUB - Publication issued
Start Date
26-Jul-2017
Completion Date
26-Jul-2017
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IEC TS 62462
Edition 2.0 2017-07
TECHNICAL
SPECIFICATION
colour
inside
Ultrasonics – Output test – Guidance for the maintenance of ultrasound
physiotherapy systems
IEC TS 62462:2017-07(en)
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IEC TS 62462
Edition 2.0 2017-07
TECHNICAL
SPECIFICATION
colour
inside
Ultrasonics – Output test – Guidance for the maintenance of ultrasound
physiotherapy systems
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 11.040.60;17.140.50 ISBN 978-2-8322-4561-3

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

® Registered trademark of the International Electrotechnical Commission
---------------------- Page: 3 ----------------------
– 2 – IEC TS 62462:2017 © IEC 2017
CONTENTS

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

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

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

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

3 Terms and definitions ...................................................................................................... 7

4 Testing regimes ............................................................................................................... 9

4.1 Acceptance testing.................................................................................................. 9

4.2 Weekly testing ........................................................................................................ 9

4.3 Annual testing ......................................................................................................... 9

5 Performance testing ........................................................................................................ 9

5.1 Acceptance testing.................................................................................................. 9

5.1.1 General ........................................................................................................... 9

5.1.2 Visual inspection ............................................................................................. 9

5.1.3 Manufacturer’s statement ................................................................................ 9

5.1.4 Ultrasonic output test ....................................................................................... 9

5.1.5 Beam uniformity and output test .................................................................... 10

5.1.6 Recording of results of acceptance test ......................................................... 11

5.1.7 Requirements and recommendation ............................................................... 11

5.2 Weekly testing ...................................................................................................... 11

5.2.1 General ......................................................................................................... 11

5.2.2 Visual inspection ........................................................................................... 11

5.2.3 Relative ultrasonic output test ........................................................................ 11

5.2.4 Beam uniformity and output test .................................................................... 11

5.2.5 Recording of results of weekly testing ............................................................ 11

5.2.6 Requirements and recommendation ............................................................... 11

5.3 Annual testing ....................................................................................................... 11

5.3.1 General ......................................................................................................... 11

5.3.2 Output power test .......................................................................................... 12

5.3.3 Effective radiating area .................................................................................. 12

5.3.4 Beam uniformity test ...................................................................................... 12

5.3.5 Pulse duty factor accuracy test ...................................................................... 12

5.3.6 Timer accuracy test ....................................................................................... 13

5.3.7 Recording of results of annual testing ............................................................ 13

5.4 Service requirement .............................................................................................. 13

Annex A (informative) Rationale for testing .......................................................................... 15

A.1 Acceptance testing................................................................................................ 15

A.2 Weekly testing ...................................................................................................... 15

A.3 Annual testing ....................................................................................................... 15

Annex B (informative) Guidance for testers .......................................................................... 16

B.1 Ultrasound power meter specifications .................................................................. 16

B.2 Room and water temperature ................................................................................ 17

B.3 Water .................................................................................................................... 17

B.4 Environmental considerations ............................................................................... 17

B.5 Ultrasound power meter checks ............................................................................ 17

B.6 Ultrasound power meter testing technique ............................................................ 17

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IEC TS 62462:2017 © IEC 2017 – 3 –

Annex C (informative) Quantitative relative ultrasonic output test using temperature

rise ................................................................................................................................ 19

Annex D (informative) Quantitative relative ultrasonic output test using calorimetry ............. 21

Annex E (informative) Qualitative test to assess changes of effective radiating area ............ 23

Annex F (informative) Example of weekly test report ............................................................ 25

Annex G (informative) Example of annual test report ........................................................... 26

Bibliography .......................................................................................................................... 30

Figure 1 – Several examples of how to prepare a set-up to check the distortion on the

water surface due to ultrasound ............................................................................................ 14

Figure 2 – Set-up where the slight angle of the treatment head to the vertical may

improve the image ................................................................................................................ 14

Figure C.1 – Example of a measurement set-up to measure the temperature rise due

to ultrasound in absorbing material ....................................................................................... 20

Figure D.1 – Schematic of equipment used within the calorimeter method for

monitoring power output of therapy treatment heads ............................................................. 21

Figure E.1 – Assessing changes of the effective radiating area using a thermochromic

phantom ............................................................................................................................... 24

Figure E.2 – Examples of different patterns observed during an experiment using a

thermochromic phantom made of silicon ............................................................................... 24

Figure G.1 – Example of a power calibration graph for two large applicator heads ................ 28

Figure G.2 – Example of a power calibration graph for two small applicator heads ................ 29

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– 4 – IEC TS 62462:2017 © IEC 2017
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ULTRASONICS – OUTPUT TEST –
GUIDANCE FOR THE MAINTENANCE OF ULTRASOUND
PHYSIOTHERAPY SYSTEMS
FOREWORD

1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising

all national electrotechnical committees (IEC National Committees). The object of IEC is to promote

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patent rights. IEC shall not be held responsible for identifying any or all such patent rights.

The main task of IEC technical committees is to prepare International Standards. In

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• the required support cannot be obtained for the publication of an International Standard,

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• the subject is still under technical development or where, for any other reason, there is the

future but no immediate possibility of an agreement on an International Standard.

Technical specifications are subject to review within three years of publication to decide

whether they can be transformed into International Standards.

IEC TS 62462, which is a Technical Specification, has been prepared by IEC technical

committee 87: Ultrasonics.

This second edition cancels and replaces the first edition published in 2007. This edition

constitutes a technical revision.
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IEC TS 62462:2017 © IEC 2017 – 5 –

This edition includes the following significant technical changes with respect to the previous

edition:

• addition of a novel method for periodic testing regarding possible changes of the effective

radiating area using thermochromic absorbers in a new Annex E;
The text of this Technical Specification is based on the following documents:
Enquiry draft Report on voting
87/640/DTS 87/647A/RVDTS

Full information on the voting for the approval of this technical specification can be found in

the report on voting indicated in the above table.

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

In this document, the following print types are used:
• requirements: in roman type;
• notes: in small roman type;
• words in bold in the text are defined in Clause 3.

The committee has decided that the contents of this document will remain unchanged until the

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the specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
A bilingual version of this publication may be issued at a later date.

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

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

colour printer.
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– 6 – IEC TS 62462:2017 © IEC 2017
INTRODUCTION

The purpose of this document is to establish standard methods for a qualitative check of the

performance of ultrasound physiotherapy devices during their lifetime, and to provide

guidance on calibration requirements and techniques.

To ensure that the ultrasound physiotherapy equipment is in an appropriate condition for

use, a regular quality check can be performed. This document defines acceptance, weekly

and annual checks. The acceptance test checks the delivery of the device and its

performance at the start of its lifetime. The weekly check is a simple qualitative check of

device operation. In the annual check, in addition to a qualitative check, a quantitative check

is defined. Examples are provided of weekly and annual test reports.

This document also gives guidance to the testers concerning the measurement of acoustic

output.

Annual testing may be performed by a skilled tester, e.g. biomedical engineer, medical

physicist, medical device service agent, commercial tester, test house, national measurement

institute or manufacturer.
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IEC TS 62462:2017 © IEC 2017 – 7 –
ULTRASONICS – OUTPUT TEST –
GUIDANCE FOR THE MAINTENANCE OF ULTRASOUND
PHYSIOTHERAPY SYSTEMS
1 Scope

This document, which is a Technical Specification, describes methods meant to assist users

of ultrasound physiotherapy systems in checking the performance of such systems. It is

applicable primarily to physiotherapists, general medical practitioners, chiropractors,

osteopaths, beauty therapists, sports professionals, biomedical engineers, medical physicists,

medical device service agents, commercial testers, test houses or manufacturers. Typical

ultrasound physiotherapy systems operate in the range from 0,5 MHz to 5 MHz. Long-wave

ultrasound therapy machines operating in the frequency range 30 kHz to 0,5 MHz are not

covered by this document.
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.

NOTE The titles of all publications referred to informatively in this document are listed in the Bibliography.

IEC 60601-2-5:2009, Medical electrical equipment – Part 2-5: Particular requirements for the

basic safety and essential performance of ultrasonic physiotherapy equipment
IEC 61161:2013, Ultrasonics – Power measurement – Radiation force balances and
performance requirements

IEC 61689:2013, Ultrasonics – Physiotherapy systems – Field specifications and methods of

measurement in the frequency range 0,5 MHz to 5 MHz
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.

ISO and IEC maintain terminological databases for use in standardization at the following

addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp

NOTE Most of the definitions in Clause 3 are taken from existing IEC standards. They have been simplified for the

purposes of this document.
3.1
acoustic working frequency
rate at which the treatment head’s contact face is vibrating
[SOURCE: IEC 61689:2013, 3.7, modified – The definition has been simplified.]
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– 8 – IEC TS 62462:2017 © IEC 2017
3.2
beam non-uniformity ratio

measure of the range of non-uniformity in the ultrasound beam produced by the treatment

head, calculated from the ratio of the acoustic intensity measured at the most intense part of

the ultrasound beam to the spatial average acoustic intensity measured for that treatment

head
[SOURCE: IEC 61689:2013, 3.15, modified – The definition has been simplified.]
3.3
degassed water
water with a low dissolved gas content

Note 1 to entry For ultrasound physiotherapy fields it is sufficient to decrease the oxygen content below 4 mg/l.

Note 2 to entry Methods for the degassing of water are described in IEC TR 62781.

3.4
effective radiating area

area of the front of the treatment face from which ultrasound is being emitted/radiated

[SOURCE: IEC 61689:2013, 3.23, modified – The definition has been simplified.]
3.5
effective intensity
eff
ratio of the ultrasonic power over the effective radiating area
3.6
hot spot

a localized peaking of the pressure distribution above values that normally can be expected

indicated by a beam non-uniformity ratio (R ) being larger than 4
3.7
output power

measure of how much ultrasonic energy is flowing out of the treatment head per unit time

[SOURCE: IEC 61161:2013, 3.3, modified – The definition has been simplified.]
3.8
tester
person who does performance testing on, or calibration of, therapy machines
3.9
treatment head

assembly comprising one ultrasonic transducer and associated parts for local application of

ultrasound to the patient
[SOURCE IEC 60601-2-5:2009, 201.3.214]
3.10
ultrasound

acoustic oscillation whose frequency is above the high-frequency limit of audible sound (about

20 kHz)
[SOURCE: IEC 60050-802:2011, 802-01-01]
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IEC TS 62462:2017 © IEC 2017 – 9 –
4 Testing regimes
4.1 Acceptance testing

After the device has been delivered to the user a first test should be performed to record the

performance at the start of the device’s lifetime. See Annex A for rationale.
4.2 Weekly testing

Weekly qualitative testing is performed by the therapy machine user, e.g. physiotherapist,

general medical practitioner, chiropractor, osteopath, beauty therapist, sports professional.

See Annex A for rationale.
4.3 Annual testing

Annual testing is performed by an accredited tester, e.g. biomedical engineer, medical

physicist, medical device service agent, commercial tester, test house, national measurement

institute, manufacturer. See Annex A for rationale.
5 Performance testing
5.1 Acceptance testing
5.1.1 General

The purpose of the test is to record the performance of a device before clinical use, or of a

device that has been repaired. The test involves a manufacturer’s statement, a visual

inspection and a quantitative relative ultrasonic output test. See Annex B for guidance for

testers.
5.1.2 Visual inspection

The first visual inspection should concentrate on the delivered items. All items should have

been delivered in accordance with the purchase specification, and they should look

undamaged.
5.1.3 Manufacturer’s statement

On delivery of a new device or after repair of an existing device, check the written system

manufacturer’s statement that the device performs in accordance with the manufacturer’s

device specifications. From this statement, it follows that the device shall be traceably

calibrated in accordance with IEC 61689 and IEC 60601-2-5.
5.1.4 Ultrasonic output test

a) To prepare a starting point for future simple quantitative output testing, either the

effective intensity or the ultrasonic output power of the device should be recorded for at

least one output setting, e.g. continuous wave, effective intensity: 1 W/cm

b) In cases where the manufacturer has stated the traceability of the calibration, there is no

need for an absolute output measurement. In all other cases, the ultrasonic output should

be calibrated in accordance with IEC 60601-2-5 and IEC 61161.

c) Once confidence is established in the calibration of the device, a prescribed method

should be used to relate the device output setting as recorded in 5.1.4 a) to a reading of a

related performance. This method could be a determination of temperature rise following

Annex C, or Annex D, or using an ultrasound power meter. For qualitative test to assess

changes of effective radiating area, follow Annex E. The method used should be
described in the record and should be used in the weekly test, see 5.2.3.
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– 10 – IEC TS 62462:2017 © IEC 2017
5.1.5 Beam uniformity and output test
5.1.5.1 General

The test is a quick check of whether the machine is outputting any ultrasound power, and of

any ‘hot spots’ or asymmetry present in the beam produced by the treatment head. It is not

a power calibration. The technique uses the ultrasound emitted by the treatment head to

disturb the surface of water in a container. The equipment needed is as follows:

a) a small container of sufficient depth to be filled with water to a maximum of 25 mm. This

container should have a bottom thickness of < 0,3 mm: for instance, a cylinder bottom

covered with a membrane made of polyester film, polyvinylidene difluoride (PVDF), or

other similar thin plastic material. See Figure 1 for a number of examples;
b) coupling gel.

NOTE Common undesirable techniques which have been used in the past to check ultrasound output are as

follows:

• placing a few drops of water on the upturned treatment head, then timing how long it takes for the water to

boil off;

• making a small well of water about the treatment head using some tape, and observing the disturbance of the

water surface by the ultrasound.

Modern physiotherapy units have automatic cut-offs (power down) when the treatment head has insufficient

contact with the patient or is not immersed. Techniques such as those described within this note will often trigger

the automatic shutdown of the head and thus give a false indication that the ultrasound therapy machine is faulty.

Subjecting a treatment head to poor patient contact or poor water immersion will shorten the lifetime of the device.

For these reasons, using a container of water to see the effect of the ultrasound on a surface of water can avoid

this.
Further valuable reading can be found in [1], [2], [3], [4] .
5.1.5.2 Procedure
The procedure is as follows:

a) Hold the treatment head so that the face is pointing upwards. Apply coupling gel to the

face of the treatment head. Place the container on the face of the treatment head and

make sure that all coupling gel is properly distributed without air bubbles. See Figure 1.

b) Fill the container with water to a depth of 5 mm to 20 mm. (Tap water is adequate for this

qualitative and quick test.)

c) A slight angle of the treatment head to the vertical may improve the image. See Figure 2.

d) Turn on the ultrasound to full power, or less if this is sufficient to observe a disturbance

of the water. (A disturbance of the water will be observed when looking from the side, and

it may be necessary to move the treatment head around a little and to also change the

angle to the surface to see the disturbance. The effect which can be seen is shown in

Figure 1.) If the treatment head is less than 5 mm below the surface and/or exactly

parallel to it, then the ultrasound may turn off due to an automatic safety sensor, as

damage to the ultrasound therapy machine may otherwise occur.
The features of the water disturbance to note are as follows:
1) the circular symmetry of the pattern;

NOTE Changes in the circular symmetry can be an indication of changes in the effective radiating area.

2) whether there are any sharp peaks (hot spots) showing (see Figure 1 c));

3) whether the appearance of the disturbance changed in height or symmetry since the

last time it was checked;

4) whether the pattern remained the same but decreased in height with reduction in

ultrasound power.
—————————
Numbers in square brackets refer to the Bibliography.
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IEC TS 62462:2017 © IEC 2017 – 11 –
5.1.6 Recording of results of acceptance test

The results of the acceptance test shall be recorded. Annex F gives an example where the

results of the acceptance test can be recorded as a start of the weekly test report.

5.1.7 Requirements and recommendation

Patterns obtained by performing 5.1.5, which are not circularly symmetric and/or have sharp

peaks, indicate that the treatment head may not be performing appropriately and could be

unsafe.

In case of non-conformance with one of the events listed in 5.1.2, 5.1.3, 5.1.4, 5.1.5, the

manufacturer should be consulted to check the device.
5.2 Weekly testing
5.2.
...

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