SIST EN 61847:2002

SLOVENSKI STANDARD
01-september-2002
Ultrasonics - Surgical systems - Measurement and declaration of the basic output
characteristics (IEC 61847:1998)
Ultrasonics - Surgical systems - Measurement and declaration of the basic output
characteristics
Ultraschall - Chirurgische Systeme - Messung und Deklaration der grundlegenden
Ausgangsrößen
Ultrasons - Systèmes de chirurgie - Mesure et déclaration des caractéristiques de sortie
Ta slovenski standard je istoveten z: EN 61847:1998
ICS:
11.040.01 Medicinska oprema na Medical equipment in general
splošno
17.140.50 Elektroakustika Electroacoustics
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

INTERNATIONAL
IEC
STANDARD
First edition
1998-01
Ultrasonics – Surgical systems –
Measurement and declaration of the basic
output characteristics
Ultrasons – Systèmes de chirurgie –
Mesure et déclaration des caractéristiques
de sortie
 IEC 1998 Droits de reproduction réservés  Copyright - all rights reserved
Aucune partie de cette publication ne peut être reproduite ni No part of this publication may be reproduced or utilized in
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CODE PRIX
Commission Electrotechnique Internationale
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International Electrotechnical Commission
Pour prix, voir catalogue en vigueur
For price, see current catalogue

– 2 – 61847 © IEC:1998 (E)
CONTENTS
Page
FOREWORD . 3
INTRODUCTION . 4
Clause
1 Scope . 5
2 Normative references. 5
3 Definitions. 6
4 List of symbols. 9
5 General measurement requirements. 9
5.1 Operating conditions . 9
5.2 Load conditions. 9
5.3 Preparation for measurements . 10
6 Measurement procedures. 10
6.1 Primary tip vibration excursion . 10
6.2 Secondary tip vibration excursion . 11
6.3 Drive frequency. 11
6.4 Tip vibration frequency. 11
6.5 Derived output acoustic power and output acoustic power . 12
6.6 Directivity pattern. 13
6.7 Primary tip vibration excursion modulation. 13
6.8 Duty cycle. 14
6.9 Quiescent electrical power . 14
6.10 Maximum electrical power. 14
6.11 Primary acoustic output area. 15
6.12 Secondary acoustic output area . 15
6.13 Power reserve index . 15
7 Declaration of output characteristics. 15
Figures. 16
Annexes
A Measurement methods and conditions. 21
B Theory of operation of ultrasonic surgical devices. 26
C Bibliography. 29

61847 © IEC:1998 (E) – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
__________
ULTRASONICS – SURGICAL SYSTEMS –
Measurement and declaration of the basic output characteristics
FOREWORD
1) The IEC (International Electrotechnical Commission) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of the 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, the IEC publishes International Standards. 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. The 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 the 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 National Committees.
3) The documents produced have the form of recommendations for international use and are published in the form
of standards, technical reports or guides and they are accepted by the National Committees in that sense.
4) In order to promote international unification, IEC National Committees undertake to apply IEC International
Standards transparently to the maximum extent possible in their national and regional standards. Any
divergence between the IEC Standard and the corresponding national or regional standard shall be clearly
indicated in the latter.
5) The IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with one of its standards.
6) Attention is drawn to the possibility that some of the elements of this International Standard may be the subject
of patent rights. The IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 61847 has been prepared by IEC technical committee 87:
Ultrasonics.
The text of this standard is based on the following documents:
FDIS Report on voting
87/114/FDIS 87/117/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.
Annexes A, B and C are for information only.
In this standard the following print types are used:
– Requirements: in roman type
– Test specifications: in italic type
– Notes: in small roman type
– Words in bold in the text are defined in clause 3.
A bilingual version of this standard may be issued at a later date.

– 4 – 61847 © IEC:1998 (E)
INTRODUCTION
Ultrasonic surgical systems, operating in the 20 kHz to 60 kHz range, are used widely in
ophthalmology and neurosurgery to fragment or disintegrate and aspirate unwanted tissue.
Their commercial use in ophthalmology started in 1970. Their application in neurosurgery
followed about 10 years later. Ultrasonic surgical systems are also widely used in oncology
surgery.
This International Standard defines the parameters which characterize the output and
performance of open and closed site ultrasonic surgical systems, and indicates which
parameters should be declared. In addition, measurement procedures are described so that
technically qualified people will be able to report on the parameters in a uniform and
understandable fashion. An open surgical site is one in which the incision is large relative to
the size of the applicator tip being inserted thus precluding any increase in pressure of the
organ due to an imbalance of irrigant flow and suction flow. An example of a closed surgical
site is an eye where the incision is closely controlled.
This International Standard does not provide any guidance on what is the resultant safety or
efficacy of devices described by these parameters since very little scientifically controlled data
are available by which such judgements can be made.

61847 © IEC:1998 (E) – 5 –
ULTRASONICS – SURGICAL SYSTEMS –
Measurement and declaration of the basic output characteristics
1 Scope
This International Standard specifies:
– the essential non-thermal output characteristics of ultrasonic surgical units;
NOTE 1 – One of the parameters of interest is output acoustic power. This standard addresses only the low-
frequency (under 100 kHz) component of the total delivered energy. The high-frequency component, which probably
relates to cavitation developed at the tip, is not addressed (see A.4).
– methods of measurement of these output characteristics;
– those characteristics which should be declared by the manufacturers of such equipment.
NOTE 2 – In the interest of clarity, this standard does not address all of the complex surfaces and shapes possible
for applicator tips. A straight tubular shape is used in the description of the parameters and measurements to be
made. It is left to the user of this standard to adapt the basic methodology described to more complex designs if
required.
This International Standard is applicable to equipment which meets the requirements of a, b
and c below:
a) ultrasonic surgical systems operating in the frequency range 20 kHz to 60 kHz; and
b) ultrasonic surgical systems, whose use is the fragmentation or cutting of human tissue,
whether or not those effects are delivered in conjunction with tissue removal or coagulation;
and
c) ultrasonic surgical systems, in which an acoustic wave is conducted by means of a
specifically designed wave guide to deliver energy to the surgical site.
NOTE 3 – Examples of these types of systems are surgical aspirators, intracorporeal lithotripters, end-cutting
devices etc.
This International Standard is not applicable to:
– lithotripsy equipment which uses extracorporeally induced pressure pulses, focussed
through liquid conducting media and the soft tissues of the body;
– surgical devices used as part of the therapeutic process (hyperthermia systems);
– surgical devices whose acoustic application areas are not at the end of a longitudinally
vibrating applicator tip and therefore would not fit the monopole model used in this standard.
This International Standard does not deal with the effectiveness or safety of ultrasonic surgical
systems.
NOTE 4 – Throughout this standard, the term accuracy means the overall uncertainty expressed at the 95 %
confidence level.
2 Normative references
The following normative documents contain provisions which, through reference in this text,
constitute provisions of this International Standard. At the time of publication, the editions
indicated were valid. All normative documents are subject to revision, and parties to
agreements based on this International Standard are encouraged to investigate the possibility
of applying the most recent editions of the normative documents indicated below. Members of
IEC and ISO maintain registers of currently valid International Standards.
IEC 60500:1974, IEC standard hydrophone
IEC 61205:1993, Ultrasonics – Dental descaler systems – Measurement and declaration of the
output characteristics
– 6 – 61847 © IEC:1998 (E)
3 Definitions
For the purpose of this International Standard, the following definitions apply.
3.1
applicator tip; applied part
that part of the surgical tool which comes into direct contact with body tissues
3.2
directivity pattern
normalized variation in acoustic pressure as a function of angle at constant range from the
applicator tip
NOTE – This parameter is important when operating adjacent to body structures which are sensitive to pressure
and motion such as the endothelial cells on the inside of the cornea or acoustic nerves.
Symbol: p
fd
Unit: dimensionless plot
3.3
drive frequency
mean frequency of the driving voltage or current
NOTE – This parameter, coupled with tip vibration excursion, allows the user to compare the velocities of applicator
tips.
Symbol: f
d
Unit: kilohertz, kHz
3.4
duty cycle
for those systems which modulate the electrical drive power, the ratio of the voltage or current
pulse duration (on time) to the duration of one complete modulation cycle while the equipment
is active
Symbol: D
cy
Unit: dimensionless
3.5
maximum electrical power
the peak input electrical power to the ultrasonic handpiece when the load on the applicator tip
is gradually increased from its quiescent condition
NOTE – The peak electrical power occurs at the point at which a reduction in the primary tip vibration excursion
from its value corresponding to the occurs (see 6.9 and 6.10).
quiescent electrical power
Symbol: P
max
Unit: watts, W
3.6
output acoustic power
the acoustic power delivered by the applicator tip into water, and measured using a
calorimetric method (see 6.5)
NOTE – Measurement of acoustic power delivered by applicator tips having different output areas and/or excursion
amplitudes will facilitate application of the ALARA principle, the use of exposure levels that are as low as
reasonably achievable.
Symbol: P
a
Unit: milliwatts, mW
61847 © IEC:1998 (E) – 7 –
3.7
derived output acoustic power
the acoustic power delivered by the applicator tip into water, and derived from measurements
made using a hydrophone (see 6.5)
NOTE – Measurement of acoustic power delivered by applicator tips having different output areas and/or excursion
amplitudes will facilitate application of the ALARA principle, the use of exposure levels that are as low as
reasonably achievable.
Symbol: P
ad
Unit: milliwatts, mW
3.8
power reserve index
the ratio of maximum electrical power to quiescent electrical power
NOTE 1 – The power reserve index gives the user a measure of how much “extra” power is available to maintain a
constant tip excursion amplitude under various load conditions.
Symbol: P
i
Unit: dimensionless
NOTE 2 – The power reserve index will only allow direct comparison of different devices if those devices share the
same operating modality. Piezoelectric and magnetostrictive devices cannot be validly compared using the power
reserve index.
3.9
primary acoustic output area
the area of the projection of the solid part of the applicator tip in the direction of primary tip
vibration excursion
NOTE – Primary acoustic output area is used in determining the energy radiated from the end of an applicator
tip for different tips operating at the same vibration excursion and frequency.
Symbol: A
ap
Unit: square millimetres, mm
3.10
primary tip vibration excursion
peak-to-peak displacement of the applicator tip in the direction of maximum amplitude, at a
point on the applicator tip not more than 1 mm from its free (distal) end (see 3.2 of IEC 61205)
NOTE – The ability to fragment tissue can be correlated to primary tip vibration excursion.
Symbol: s
p
Unit: micrometre, μm
3.11
primary tip vibration excursion modulation
for those systems which modulate the electrical drive power, the percentage change in the
primary tip vibration excursion from its maximum value to its minimum value
Symbol: M
sp
Unit: dimensionless
3.12
pulse duration
for those devices which modulate the electrical drive power, the time interval beginning at the
first time the drive voltage or current exceeds a reference level and ending at the last time the
drive voltage or current returns to that level. The reference level is equal to the sum of the
minimum drive voltage or current and 10 % of the difference between the maximum and the
minimum drive voltage or current.
Symbol: t
p
Unit: milliseconds, ms
– 8 – 61847 © IEC:1998 (E)
3.13
quiescent electrical power
The input electrical power to the ultrasonic handpiece with the applicator tip unloaded, for a
given primary tip vibration excursion.
Symbol: P
q
Unit: watts, W
3.14
reference primary tip vibration excursion
The maximum primary tip vibration excursion for the combination of applicator tip and
handpiece chosen for measurement.
NOTE – The reference primary tip vibration excursion is used to obtain the values of quiescent and maximum
electrical power needed to calculate the power reserve index of a device configuration.
Symbol: s
pr
Unit: micrometre, μm
3.15
secondary acoustic output area
the area of the projection of the exposed part of the applicator tip in the direction
perpendicular to the direction of the primary tip vibration excursion and corresponding to the
second largest component of motion
Symbol: A
as
Unit: square millimetres, mm
NOTE – Definitions 3.9 and 3.15 are intended to give the basic areas of interest when considering acoustic output
of simple tubular applicator tips. They do not cover the infinite variety of complex end shapes which may be
available from individual devices.
3.16
secondary tip vibration excursion
peak-to-peak displacement of the applicator tip in a direction perpendicular to the direction of
the primary tip vibration excursion and corresponding to the direction of the second largest
component of motion, of a point on the applicator tip not more than 1 mm from its free (distal)
end
Symbol: s
s
Unit: micrometre, μm
3.17
tip vibration frequency
fundamental frequency at which the applicator tip oscillates (see 3.3 of IEC 61205)
Symbol: f
r
Unit: kilohertz, kHz
61847 © IEC:1998 (E) – 9 –
4 List of symbols
A secondary acoustic output area
as
A primary acoustic output area
ap
c speed of sound in the medium
D duty cycle
cy
f drive frequency
d
f tip vibration frequency
r
M primary tip vibration excursion modulation
sp
p directivity pattern
fd
p(r) pressure amplitude at position r
P output acoustic power
a
P derived output acoustic power
ad
P power reserve index
i
P quiescent electrical power
q
P maximum electrical power
max
s primary tip vibration excursion
p
s reference primary tip vibration excursion
pr
s secondary tip vibration excursion
s
t pulse duration
p
ρ density of the measuring medium
5 General measurement requirements
5.1 Operating conditions
Measurements shall be performed with parameters set to values recommended by the
manufacturer. The parameters to be considered are:
– ambient temperature;
– tip irrigant flow rate;
– tip vibration excursion;
– tip aspiration flow rate.
The parameters listed above are not set independently during actual surgical use. Therefore,
when a particular surgical environment is to be studied, the parameters listed above shall be
specified so that meaningful comparisons of performance can be made (see clause B.5).
5.2 Load conditions
5.2.1 For measurement of derived output acoustic power
Measurements of derived output acoustic power or output acoustic power shall be made
using degassed water (see clause A.6 for rationale and references to degassing techniques) in
a tank, lined with sound absorbing material and having a suitable size to render it essentially
anechoic for the tip vibration frequency of concern i.e. free field condition. In addition, for
devices which have suction available, sufficient flow through tip can be used to minimize the
accumulation of bubbles on the front surface of the tip.

– 10 – 61847 © IEC:1998 (E)
5.2.2 For measurements of quiescent electrical power
Measurements of quiescent electrical power to the ultrasonic handpiece shall be made with
all system fluid flow operational and with the distal end of the applicator tip in air.
5.2.3 For measurements of maximum electrical power
Measurements of maximum electrical power (the power just prior to stall) to the ultrasonic
handpiece shall be made as indicated by 5.2.2 but with the distal end of the applicator tip
loaded with a suitable acoustically absorbing material capable of loading the applicator without
damaging it.
5.3 Preparation for measurements
5.3.1 Preparation of the applicator
Prior to any measurements all surfaces and parts of the applicator shall be free from
contamination. The applicator tip, the ultrasonic handpiece and the measurement devices
which come into contact with the water and irrigant shall be cleaned with detergent and rinsed
*
with warm water (see also [1] and [2]).
5.3.2 Preparation of the water
Degassed water shall be used (see annex A for reference to suitable degassing techniques,
see also [2] and [3] of annex C).
5.3.3 Preparation of the system
The apparatus shall be allowed a warm-up period as specified by the manufacturer. If a warm-
up period is not specified by the manufacturer, a warm-up period shall be allowed which is long
enough to allow stable operation to be achieved, up to a maximum of 15 min.
6 Measurement procedures
6.1 Primary tip vibration excursion
One of the following methods shall be used for measuring the primary tip vibration
excursion. The accuracy of the vibration excursion measurement shall be better than ±10 %.
6.1.1 Optical microscope method
A microscope shall be focused on a point not more than 1,0 mm from the free end of the
applicator tip which shall be illuminated by a light beam. When the equipment is energized,
the point traces a line. The relative orientation of the applicator tip and the microscope shall
be altered until the maximum line length is observed. The line length, equal to the primary tip
vibration excursion, shall be measured to an accuracy of ±10 % by means of a calibrated
eyepiece reticule or micrometer movement. If transverse vibrations occur simultaneously then
the point on the applicator describes an elliptical path and the length of the major axis of the
ellipse shall be measured (see figure 1).
6.1.2 Laser vibrometer method
A laser vibrometer shall have an output beam spot size small enough to focus on the end of the
applicator tip. The beam shall be directed parallel to the longitudinal axis of the tip vibration
i.e. in line with the direction of tip vibration excursion to be measured. The output of the
vibrometer control module can be displayed and recorded on instruments as specified by the
laser vibrometer manufacturer.
–––––––––
*
Figures in square brackets refer to the bibliography given in annex C.

61847 © IEC:1998 (E) – 11 –
6.1.3 Feedback voltage method
For devices which have a feedback system which is directly coupled to the mechanical tip
excursion, the feedback voltage is proportional to the primary tip vibration excursion. The
optical microscope method of 6.1.1 shall be used to calibrate the feedback voltage in terms of
tip vibration excursion for a particular combination of ultrasonic handpiece and applicator.
The feedback voltage shall be displayed on an oscilloscope with a time base accurate to ±2 %
and vertical deflection amplifiers accurate to ±2 % while optical measurements are taken in
accordance with 6.1.1. Once calibrated in this fashion only the feedback voltage need be
observed to record the magnitude of tip vibration excursions.
6.2 Secondary tip vibration excursion
The following method shall be used for measuring the secondary tip vibration excursion.
The accuracy of the vibration excursion measurement shall be better than ±10 %.
6.2.1 Optical microscope
The method shall be as described in 6.1.1 but the applicator tip shall be first rotated about its
primary vibration axis while monitoring the length of the minor axis of the ellipse. The maximum
observed length of the minor axis of the ellipse shall be measured as the secondary tip
vibration excursion (see figure 1).
6.3 Drive frequency
One of the following methods shall be used. The accuracy of the drive frequency
measurement shall be better than ±2 %.
6.3.1 Frequency counter method
An electronic frequency counter shall be used to determine the frequency of the driving voltage
or current applied to the ultrasonic handpiece. The signal can be obtained either by connecting
a suitably shielded cable to the circuit locations specified by the manufacturer or by winding a
coil around the body of the ultrasonic handpiece and feeding the induced signal to a frequency
counter.
6.3.2 Spectrum analyzer method
A spectrum analyzer with a frequency range of 10 000 Hz to 100 000 Hz shall be used to
determine the frequency of the driving voltage or current. This shall be connected to the circuit
locations specified by the manufacturer.
6.4 Tip vibration frequency
One of the following methods shall be used to measure the primary tip vibration frequency.
The accuracy of the tip vibration frequency measurement shall be better than ±2 %.
6.4.1 Vibrometer method
A non-contacting vibrometer shall be used to indicate the frequency of oscillation of the applicator
tip. This shall be measured from the output of the vibrometer using an electronic frequency
counter, a spectrum analyzer or an oscilloscope with a calibrated time base (see IEC 60782).
6.4.2 Hydrophone method
A hydrophone which satisfies IEC 60500 shall be used to measure the frequency of the
radiated acoustic pressure from the applicator tip. The hydrophone shall be placed in the
range from 30 mm to 100 mm of the applicator tip to reduce the effects of nonlinear
propagation. The frequency of the hydrophone output shall be measured using an electronic
frequency counter, a spectrum analyzer or an oscilloscope with a calibrated time base.

– 12 – 61847 © IEC:1998 (E)
6.5 Derived output acoustic power and output acoustic power
Derived output acoustic power or output acoustic power shall be determined using the
method specified in 6.5.1 or 6.5.2, respectively.
6.5.1 Derived output acoustic power – Hydrophone method
This method is based on the use of a calibrated hydrophone. The uncertainty of the
determination of derived output acoustic power shall be ±20 %. As a method based on a
single point sensor and a measurement at a single distance from the applicator tip, it is
chosen to eliminate the ideal requirement of integrating the pressure field and to avoid the
possibility of cavitational shielding (see clause A.4). A hydrophone which satisfies IEC 60500
shall be used to measure pressure at a known distance from the applicator tip. Then, using
the model of a monopole or a dipole source (see below), the derived output acoustic power
can be calculated for any tip vibration excursion desired. The applicator shall be positioned so
that the axis of symmetry of the primary tip vibration excursion coincides with the plane of
the geometric axis of the hydrophone track.
An applicator tip which reciprocates in the direction of its primary tip vibration excursion
(see figure 2) and which acts as a source which is small compared to the wavelength in the
acoustic medium can be considered as a monopole (see [4] and [5]). The general case for an
ultrasonic surgical device deeply immersed in the water tank is that the derived output
acoustic power is given by the formula:
2|π pr()|
r
=
P
ad
ρc
where
r is the separation of the applicator tip and the hydrophone;
p(r) is the pressure amplitude measured at r;
ρ is the density of the measuring medium;
c is the speed of sound in the medium.
NOTE – If the acoustic pressure is determined in terms of r.m.s. acoustic pressure, p , then p(r) is replaced
rms
p
by 2 in the above equation.
rms
Many devices, however, have applicator tips which are designed to be in contact with the
tissue while the rest of the applicator is outside the body. For these devices the applicator tip
shall be positioned so that it is approximately 1/4 wavelength beneath the surface of the water
in the measuring chamber. For this special case, whether for measurement convenience or so
as not to add the energy radiated from the handle which is never put into tissue contact, the
monopole source is reflected from the water/air boundary. This produces an effective second
monopole source, 180° out of phase with the monopole tip source. Therefore this combination
will effectively act as a dipole source.
For this case, where the applicator tip is approximately 1/4 wavelength beneath the surface of
the water, the derived output acoustic power is given by (see A.8):
π |(pr)|
r
=
P
ad
2ρc
where
r is the distance from the hydrophone to the surface of the water.
A hydrophone which satisfies IEC 60500 shall be used to measure pressure at a known
distance from the intersection of the axis of the tip and the surface of the water (see figure
A.2). Then, using the model of a dipole source, above, the derived output acoustic power
can be calculated for any tip vibration excursion desired.

61847 © IEC:1998 (E) – 13 –
6.5.2 Output acoustic power – Calorimeter method
This is an alternative but much less repeatable method than the hydrophone-based method
specified in 6.5.1. However, it can be used as a first order approximation.
The end of the applicator tip shall be inserted into a calorimeter containing an absorbing fluid.
The rate of temperature rise of the absorbing fluid shall be determined and used to calculate
the power delivered by the probe. It should be noted that depth of immersion of the applicator
tip will affect the results obtained with this method (see [1] and [3]).
6.6 Directivity pattern
The directivity pattern (field distribution) shall be determined by measuring the angular
distribution, about a centre of rotation, of the magnitude of the acoustic pressure field at a
specified range. The hydrophone shall satisfy IEC 60500. The hydrophone shall be mounted on
a circular track. It shall be moved in a water bath over a 180° sector. The applicator shall be
positioned so that the axis of symmetry of the primary tip vibration excursion coincides with
the plane of the geometric axis of the hydrophone track.
NOTE – For straight symmetrical applicator tips the direction of maximum amplitude coincides with the axis of
symmetry of the applicator. However, for curved or bent tips the motion at the distal end of the applicator tip will
be at an angle to the axis of the ultrasonic handpiece (applicator).
For devices where the applicator tip is designed to be in contact with the tissue while the rest
of the applicator is outside the body, the applicator tip shall be positioned so that it is
approximately 1/4 wavelength in water beneath the surface of the water in the measuring
chamber. For this condition, the centre of rotation shall be at the intersection of the surface of
the water and the axis of rotation of the applicator tip (see figure 3).
For percutaneous devices where the majority of the long slender applicator tip is within the
body, the applicator tip may be deeply immersed in the water chamber. For this condition, the
distal end of the applicator tip shall be used as the centre of rotation.
For the above conditions, the hydrophone shall be mounted so as to maintain a constant
sensitivity in the direction of the applicator tip. The separation between hydrophone and
applicator tip as well as the depth of immersion of the applicator tip shall be noted. The
separation of the applicator tip and the hydrophone shall be constant to within 2 mm during
the measurement.
6.7 Primary tip vibration excursion modulation
The following method shall be used for the determination of primary tip vibration excursion
modulation. The accuracy of the measurement shall be at least ±15 %.
6.7.1 Laser vibrometer method
Use the method described in 6.1.2 to determine the change in vibration excursion during the
modulation cycle. The primary tip vibration excursion modulation, M , expressed as a
sp
percentage, is given by:
M = {(s – s )/s } × 100
sp p on p off p on
where
s is the primary tip vibration excursion during the on-time;
p on
s is the primary tip vibration excursion during the off-time.
p off
– 14 – 61847 © IEC:1998 (E)
6.8 Duty cycle
For systems which modulate electrical drive power, the duty cycle is determined as follows.
The drive voltage or current shall be displayed on an oscilloscope with a time base accurate to
±2 % and vertical deflection amplifiers accurate to ±2 %. Determine the minimum and
maximum peak-to-peak drive levels.
NOTE – It is assumed here that the peak-to-peak voltage or current is being measured and that the minimum peak-
to-peak level may or may not be zero.
Determine a reference level from the sum of the minimum drive voltage or current and 10 % of
the difference between the maximum and minimum drive voltage or current levels. The pulse
duration, t , is determined from the oscilloscope trace by measuring the time interval between
p
the first time, t , that the electrical drive signal exceeds the reference level and ending at the
last time, t , that the electrical drive signal returns to the reference level (see figure 4). Thus,
the pulse duration, t , is given by:
p
t = t – t
p 2 1
If t is the time at which the electrical drive signal exceeds the reference level at the start of the
next pulse cycle, the duty cycle, D is given by:
cy
t
p
=
D
cy
−
t t
6.9 Quiescent electrical power
Set the primary tip vibration excursion to the desired level. Then, by using a phase-
corrected wattmeter designed for ultrasonic applications, measure the electrical power directly
into the ultrasonic handpiece to an accuracy of ±10 %.
6.10 Maximum electrical power
Set the primary tip vibration excursion to its maximum level. Then, by using a phase-
corrected wattmeter designed for ultrasonic applications, measure the electrical power directly
into the ultrasonic handpiece to an accuracy of ±10 %. In a water bath as shown in figure 5,
load the surgical tip in the direction of the primary tip vibration excursion. Loading shall be
effected against a material which will not damage the applicator tip. An open cell plastic foam
or other water-containing medium may be used. The density of the loading material shall be
sufficient to drive the input electrical power to the ultrasonic handpiece to the maximum value
and to reduce the reference primary tip excursion. Measure the electrical drive power as the
load is increased and note the maximum value reached just before the primary tip vibration
excursion is reduced from its maximum excursion.
NOTE – The primary tip vibration excursion may be monitored using such methods as those described in 6.1.3.

61847 © IEC:1998 (E) – 15 –
6.11 Primary acoustic output area
For the specific example of a hollow cylinder applicator tip, the primary acoustic output area
can be computed. Measure the inside and outside diameters of a hollow tubular applicator tip.
The primary acoustic output area is given by the area of the projected annular ring formed by
the two diameters and determined from (see figure 2):
π
2 2
= ( − )
A dd
ap
o i
where
d is the outside diameter of the projected annular ring;
o
d is the inside diameter of the projected annular ring.
i
6.12 Secondary acoustic output area
For the specific example of a hollow cylinder applicator tip, the secondary acoustic output
area can be computed. In the direction of the secondary tip vibration excursion, the
secondary acoustic output area is calculated from the projected rectangle by (see figure 6):
= l
A d
as o
where
d is the diameter of the exposed tip;
o
l is the length of the exposed tip.
6.13 Power reserve index
The power reserve index is an indication of the relationship between the maximum available
input electrical power, P , and the electrical power necessary to keep the surgical handpiece
max
running without any external (tissue) load applied, P . The power reserve index is given by:
q
P
max
P =
i
P
q
See cautionary note in clause 7.
7 Declaration of output characteristics
The following characteristics shall be declared in the accompanying documents of an ultrasonic
surgical system:
NOTE 1 – For the rationale on the use and specification of these parameters, see clause B.4.
– reference primary tip vibration excursion for each type of applicator tip (i.e. the
maximum primary tip vibration excursion);
– primary acoustic output area for each type of applicator tip;
– drive frequency for each ultrasonic handpiece;
– derived output acoustic power or output acoustic power for each type of applicator tip
operating at the reference primary tip vibration excursion;
NOTE 2 – When declaring this characteristic care must be taken to ensure that the terminology appropriate to the
method of measurement is noted. See 6.5.
– the type of frequency control of the system, i.e. whether initial tuning is required with later
changes during the operation or if there is continuous automatic tuning of drive frequency,
independent of load, during the operation;
NOTE 3 – This parameter gives the user an indication of how consistently a system can maintain a particular
setting without the need for frequent operator intervention.

– 16 – 61847 © IEC:1998 (E)
– power reserve index corresponding to the reference primary tip vibration excursion for
each ultrasonic handpiece/applicator tip combination.
NOTE 4 – The absolute number is dependent on the type of transducer used. Therefore caution should be
exercised not to use the power reserve index to compare the performance of dissimilar transducers.
Geometric
axis of tip
Direction of
secondary
tip excursion
Spot of reflected
light as seen
through scope
Light
beam
Direction of
primary tip
vibration
excursion
Microscope
Spot traces a
straight line
when tip is
vibrating and
there is no
secondary (transverse)
excursion
Spot traces an elliptical
line when the tip has
combined primary (longitudinal)
and secondary (transverse)
excursion
IEC  160/98
Figure 1 – Measuring the primary and secondary tip vibration excursion
Litgh beam
61847 © IEC:1998 (E) – 17 –
Inside diameter (d )
i
A
ap
Outside diameter (d )
o
Direction of primary tip
vibration excursion
IEC  161/98
Figure 2 – Example of a primary acoustic output area

– 18 – 61847 © IEC:1998 (E)
Handpiece / applicator
(not to scale)
r = 0 at water surface
Origin point of measurement
Tip depth found for
coordinate system
maximum pressure
(see section 6.5.1)
Top of water surface
θ = +90° θ = -90°
θ = +45°
θ = -45°
Path of - scans
r θ
θ = 0°
IEC  162/98
(θ = +90° to -90°)
Figure 3 – Measuring the pressure field

61847 © IEC:1998 (E) – 19 –
V
max
V
min
On time Off time
t
t 3 IEC  163/98
1 t
Figure 4 – Illustration of the method of determining duty cycle from an oscilloscope trace.
The dotted line is at a level equal to the minimum peak-to-peak level plus 10 % of the difference
between the maximum and the minimum peak-to-peak levels

– 20 – 61847 © IEC:1998 (E)
Move ultrasonic handpiece into
acoustic absorbing material until
maximum power level is achieved
P
max
Power
Beaker
Load
Water
Acoustic absorbing material
IEC  164/98
Figure 5 – Measuring the maximum electrical power (P ) at a given primary
max
tip vibration excursion (s )
p
Direction of secondary
tip vibration excursion
d
Surgical tip
l
A
as
Protective
sleeve or flue
(if used)
IEC  165/98
Figure 6 – Example of a secondary acoustic output area

61847 © IEC:1998 (E) – 21 –
Annex A
(informative)
Measurement methods and conditions
A.1 Optical microscope method
This method is based on direct observation of the tip oscillation with a microscope to view a
spot of light reflected from the probe surface. To produce the spot, a miniature fibre optic is
used or a pinhole located at the back focal plane of a condenser lens; the magnified image of
the pinhole should be no greater than 5 % of the amplitude of tip oscillation. Assuming a
circular spot, the peak-to-peak excursion is determined by measuring the peak-to-peak
response and subtracting the width of the optical trace.
The magnification of the microscope is in the range of 60× to 200×. The scale is calibrated in
micrometres with at least 400 μm full-scale.
A.2 Vibrometer method
As stated in IEC 60782 [1], methods, using vibrometers of different types for the measurement
of transducer vibrational displacement amplitude, are secondary methods, used for transducers
of both A and P categories in unloaded condition (category P transducers without liquid). They
are also applicable for measurements of the displacement amplitude at the rear side of
transducers in the loaded condition.
Non-contacting high-frequency vibrometers of different types should be used in this method
(see [1] of appendix D). The scale of the instrument should be graduated directly in
micrometres, its frequency range being 8 kHz to 100 kHz and the dynamical range 0,5 μm to
100 μm. The measurement error should be not more than ±10 %. Vibrometers used with
magnetostrictive transducers should not be disturbed by strong variable magnetic fields.
A.3 Output acoustic power using the calorimeter method
The basis of the calorimetric method of measuring the acoustical power and its limitations are
discussed in references [1] and [3]. The following is based on reference [1].
The calorimetric method of measuring acoustical power is based on the effect of sound
absorption in liquids and their heating due to absorbed energy. It is well suited for measuring
the acoustical power in the non-linear range, i.e. at high power levels.
It may also be used at low power levels, provided that the temperatures rise due to ultrasound
absorption in the liquid is not too small. At high energy levels the liquid may partly vaporize or
atomize. The energy used for this does not contribute to the heating of the liquid. Therefore the
energy level should not be too high.
Some factors may considerably reduce the accuracy of the method, notably the direct heat
conduction from the transducer to the liquid load, heat exchange between the liquid and the
surroundings and the occurrence of standing waves.
In order to eliminate or to diminish the i
...