SIST EN 61391-2:2010
Ultrasonics - Pulse-echo scanners - Part 2: Measurement of maximum depth of penetration and local dynamic range (IEC 61391-2:2010)
Ultrasonics - Pulse-echo scanners - Part 2: Measurement of maximum depth of penetration and local dynamic range (IEC 61391-2:2010)
This part of IEC 61391 defines terms and specifies methods for measuring the maximum depth of penetration and the local dynamic range of real-time ultrasound B-MODE scanners. The types of transducers used with these scanners include: - mechanical probes; - electronic phased arrays; - linear arrays; - curved arrays; - two-dimensional arrays; - three-dimensional scanning probes based on a combination of the above types. All scanners considered are based on pulse-echo techniques. The test methodology is applicable for transducers operating in the 1 MHz to 15 MHz frequency range operating both in fundamental mode and in harmonic modes that extend to 15 MHz. However, testing of harmonic modes above 15 MHz is not covered by this standard.
Ultraschall - Impuls-Echo-Scanner - Teil 2: Messung der maximalen Eindringtiefe und des lokalen Dynamikbereichs (IEC 61391-2:2010)
Ultrasons - Scanners à impulsion et écho - Partie 2 : Mesure de la profondeur maximale de pénétration et de la plage dynamique locale (CEI 61391-2:2010)
La CEI 61391-2:2010 définit les termes et spécifie les méthodes de mesure de la profondeur maximale de pénétration et de la plage dynamique locale des scanners ultrasoniques en temps réel, en mode B. Les types de transducteurs utilisés avec ces scanners comprennent ce qui suit:
- sondes à balayage mécanique;
- réseaux de phase électroniques;
- réseaux linéaires (barrettes);
- réseaux courbes;
- réseaux bidimensionnels;
- sondes à balayage tridimensionnel, basées sur une combinaison des types ci-dessus.
Tous les scanners considérés sont basés sur les techniques "impulsion et écho". La méthodologie d'essai est applicable aux transducteurs fonctionnant dans la gamme des fréquences entre 1 MHz et 15 MHz, en mode fondamental et en modes harmoniques allant jusqu'à 15 MHz. Toutefois, les essais en modes harmoniques, au-dessus de 15 MHz, ne sont pas couverts par la présente norme.
Ultrazvok - Impulzno-odmevni skenerji - 2. del: Meritev največje globine prodiranja in lokalno dinamično območje (IEC 61391-2:2010)
Ta del 61391 opredeljuje izraze in določa metode za meritev največje globine prodiranja in lokalno dinamično območje ultrazvočnih skenerjev B-MODE v realnem času. Vrste pretvornikov, ki se uporabljajo s temi skenerji, vključujejo: - mehanske sonde; - elektronske fazne nize; - linearne nize; - ukrivljene nize; - dvodimenzionalne nize; - tridimenzionalne sonde za skeniranje na osnovi kombinacije zgoraj navedenih vrst. Vsi obravnavani skenerji temeljijo na impulzno-odmevnih tehnikah. Preskusna metodologija velja za pretvornike, ki obratujejo v frekvenčnem razponu med 1 MHz in 15 MHz v osnovnem načinu, in harmoničnih načinih, ki segajo do 15 MHz. Vendar pa ta standard ne zajema preskušanja harmoničnih načinov nad 15 MHz.
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
SIST EN 61391-2:2010
01-september-2010
8OWUD]YRN,PSXO]QRRGPHYQLVNHQHUMLGHO 0HULWHYQDMYHþMHJORELQHSURGLUDQMD
LQORNDOQRGLQDPLþQRREPRþMH ,(&
Ultrasonics - Pulse-echo scanners - Part 2: Measurement of maximum depth of
penetration and local dynamic range (IEC 61391-2:2010)
Ultraschall - Impuls-Echo-Scanner - Teil 2: Messung der maximalen Eindringtiefe und
des lokalen Dynamikbereichs (IEC 61391-2:2010)
Ultrasons - Scanners à impulsion et écho - Partie 2 : Mesure de la profondeur maximale
de pénétration et de la plage dynamique locale (CEI 61391-2:2010)
Ta slovenski standard je istoveten z: EN 61391-2:2010
ICS:
11.040.55 'LDJQRVWLþQDRSUHPD Diagnostic equipment
SIST EN 61391-2:2010 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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SIST EN 61391-2:2010
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SIST EN 61391-2:2010
EUROPEAN STANDARD
EN 61391-2
NORME EUROPÉENNE
April 2010
EUROPÄISCHE NORM
ICS 17.140.50
English version
Ultrasonics -
Pulse-echo scanners -
Part 2: Measurement of maximum depth of penetration
and local dynamic range
(IEC 61391-2:2010)
Ultrasons - Ultraschall -
Scanners à impulsion et écho - Impuls-Echo-Scanner -
Partie 2 : Mesure de la profondeur Teil 2: Messung der maximalen
maximale de pénétration et de la plage Eindringtiefe und des lokalen
dynamique locale Dynamikbereichs
(CEI 61391-2:2010) (IEC 61391-2:2010)
This European Standard was approved by CENELEC on 2010-04-01. 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
© 2010 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 61391-2:2010 E
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SIST EN 61391-2:2010
EN 61391-2:2010 - 2 -
Foreword
The text of document 87/400/CDV, future edition 1 of IEC 61391-2, prepared by IEC TC 87, Ultrasonics,
was submitted to the IEC-CENELEC parallel vote and was approved by CENELEC as EN 61391-2 on
2010-04-01.
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
(dop) 2011-01-01
national standard or by endorsement
– latest date by which the national standards conflicting
(dow) 2013-04-01
with the EN have to be withdrawn
Annex ZA has been added by CENELEC.
__________
Endorsement notice
The text of the International Standard IEC 61391-2:2010 was approved by CENELEC as a European
Standard without any modification.
In the official version, for Bibliography, the following notes have to be added for the standards indicated:
IEC 60601-1:2005 NOTE Harmonized as EN 60601-1:2006 (not modified).
IEC 61161:1992 NOTE Harmonized as EN 61161:1994 (not modified).
__________
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SIST EN 61391-2:2010
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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 61391-1 2006 Ultrasonics - Pulse-echo scanners - EN 61391-1 2006
Part 1: Techniques for calibrating spatial
measurement systems and measurement of
system point spread function response
IEC 62127-1 2007 Ultrasonics - Hydrophones - EN 62127-1 2007
Part 1: Measurement and characterization of
medical ultrasonic fields up to 40 MHz
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SIST EN 61391-2:2010
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SIST EN 61391-2:2010
IEC 61391-2
®
Edition 1.0 2010-01
INTERNATIONAL
STANDARD
Ultrasonics – Pulse-echo scanners –
Part 2: Measurement of maximum depth of penetration and local dynamic range
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
PRICE CODE
W
ICS 17.140.50 ISBN 2-8318-1075-3
® Registered trademark of the International Electrotechnical Commission
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SIST EN 61391-2:2010
– 2 – 61391-2 © IEC:2010(E)
CONTENTS
FOREWORD.4
INTRODUCTION.6
1 Scope.8
2 Normative references .8
3 Terms and definitions .8
4 General requirement.13
5 Environmental conditions.13
6 Equipment and data required.14
6.1 General .14
6.2 Phantoms.14
6.2.1 Phantoms required .14
6.2.2 Phantom for maximum depth of penetration.14
6.2.3 Phantoms to estimate local dynamic range .15
6.3 Test equipment for measuring local dynamic range .15
6.4 Digitized image data.17
7 Measurement methods .19
7.1 System sensitivity: maximum depth of penetration.19
7.1.1 Scanning system settings .19
7.1.2 Image acquisition .19
7.1.3 Analysis.20
7.2 Local dynamic range .22
7.2.1 Scanning system settings .22
7.2.2 Measurement method .22
7.2.3 Type II testing for measuring local dynamic range .23
7.2.4 Estimating local dynamic range using backscatter contrast.24
Annex A (informative) Phantom for determining maximum depth of penetration .26
Annex B (informative) Local dynamic range using acoustical test objects.28
Bibliography.35
Figure 1 – Arrangement for measuring local dynamic range using an acoustic-signal
injection technique.16
Figure 2 – Arrangement for measuring local dynamic range using an acoustically-
coupled burst generator .17
Figure 3 – Image of the penetration phantom.20
Figure 4 – Mean digitized image data value vs. depth for the phantom image data
(A(j)) and for the noise image data (A'(j)) .21
Figure 5 – Digitized-image data vs. attenuator setting during local dynamic range
measurements using acoustic signal injection.23
Figure 6 – Image of phantom with inclusions (circles) .24
Figure 7 – Ensemble-average mean pixel value vs. backscatter contrast of inclusions.25
Figure A.1 – Phantom for maximum depth of penetration tests.26
Figure B.1 – Possible arrangement of reflectors for determining local dynamic range .29
Figure B.2 – Displayed intensity (or image pixel value) vs. reflector reflection
coefficient .30
Figure B.3 – Flat ended wire test object for determining local dynamic range.32
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Figure B.4 – The experimentally observed backscattering cross section of flat-ended
stainless-steel wires as a function of diameter for three frequencies: U 9.6 MHz; :
4.8 MHz; ‘: 2.4 MHz [33].33
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INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ULTRASONICS –
PULSE-ECHO SCANNERS –
Part 2: Measurement of maximum depth
of penetration and local dynamic range
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 recommendations 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 61391-2 has been prepared by IEC technical committee 87:
Ultrasonics.
The text of this standard is based on the following documents:
Enquiry draft Report on voting
87/400/CDV 87/426/RVC
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.
Terms in bold in the text are defined in Clause 3.
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SIST EN 61391-2:2010
61391-2 © IEC:2010(E) – 5 –
A list of all parts of the IEC 61391 series, published under the general title Ultrasonics –
Pulse-echo scanners, can be found on the IEC website.
The committee has decided that the contents of this publication will remain unchanged until
the maintenance result 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.
A bilingual version of this standard may be issued at a later date.
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INTRODUCTION
An ultrasonic pulse-echo scanner produces images of tissue in a scan plane by sweeping a
narrow pulsed beam of ultrasound through the section of interest and detecting the echoes
generated by reflection at tissue boundaries and by scattering within tissues. Various
transducer types are employed to operate in a transmit/receive mode to generate/detect the
ultrasonic signals. Ultrasonic scanners are widely used in medical practice to produce images
of soft-tissue organs throughout the human body.
This standard is being published in two or more parts:
• Part 1 deals with techniques for calibrating spatial measurement systems and
measurement of system point spread function response;
• Part 2 deals with measurement of system sensitivity (maximum depth of penetration) and
local dynamic range.
This standard describes test procedures for measuring the maximum depth of penetration
and the local dynamic range of these imaging systems. Procedures should be widely
acceptable and valid for a wide range of types of equipment. Manufacturers should use the
standard to prepare their specifications; users should employ the standard to check
performance against those specifications. The measurements can be carried out without
interfering with the normal working conditions of the machine.
Typical phantoms are described in Annex A. The structures of the phantoms are not specified
in detail; instead, suitable types of overall and internal structures for phantoms are described.
Similar commercial versions of these test objects are available. The specific structure of a test
object selected by the user should be reported with the results obtained when using it.
The performance parameters described herein and the corresponding methods of
measurement have been chosen to provide a basis for comparison between similar types of
apparatus of different makes but intended for the same kind of diagnostic application. The
manufacturer’s specifications of maximum depth of penetration and local dynamic range
must allow comparison with the results obtained from the tests described in this standard. It is
intended that the sets of results and values obtained from the use of the recommended
methods will provide useful criteria for predicting performance with respect to these
parameters for equipment operating in the 1 MHz to 15 MHz frequency range. However,
availability and some specifications of test objects, such that they are similar to tissue in vivo,
are still under study for the frequency range 10 MHz to15 MHz.
The procedures recommended in this standard are in accordance with IEC 60601-1 [1] and
IEC 61391-1.
Where a diagnostic system accommodates more than one option in respect of a particular
system component, for example the transducer, it is intended that each option be regarded as
a separate system. However, it is considered that the performance of a machine for a specific
task is adequately specified if measurements are undertaken for the most significant
combinations of machine control settings and accessories. Further evaluation of equipment is
obviously possible but this should be considered as a special case rather than a routine
requirement.
The paradigm used for the framework of this standard is to consider the ultrasound imaging
system to be composed architecturally of a front-end (generally consisting of the ultrasound
transducer, amplifiers, digitizers and beamformer), a back-end (generally consisting of signal
conditioning, image formation, image processing and scan conversion) and a display
(generally consisting of a video monitor but also including any other output device). Under
ideal conditions it would be possible for users to test performance of these components of the
system independently. It is recognized, however, that some systems and lack of some
laboratory resources might prevent this full range of measurements. Thus, the specifications
and measurement methods described in this standard refer to image data that are provided in
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61391-2 © IEC:2010(E) – 7 –
a digitalized format by the ultrasound machine and that can be accessed by users. Some
scanners do not provide access to digitized image data. For this group of scanners, tests can
be done by utilizing frame grabbers to record images. Data can then be analyzed in a
computer in the same manner as for image data provided directly by the scanner.
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ULTRASONICS –
PULSE-ECHO SCANNERS –
Part 2: Measurement of maximum depth
of penetration and local dynamic range
1 Scope
This part of IEC 61391 defines terms and specifies methods for measuring the maximum
depth of penetration and the local dynamic range of real-time ultrasound B-MODE
scanners. The types of transducers used with these scanners include:
– mechanical probes;
– electronic phased arrays;
– linear arrays;
– curved arrays;
– two-dimensional arrays;
– three-dimensional scanning probes based on a combination of the above types.
All scanners considered are based on pulse-echo techniques. The test methodology is
applicable for transducers operating in the 1 MHz to 15 MHz frequency range operating both
in fundamental mode and in harmonic modes that extend to 15 MHz. However, testing of
harmonic modes above 15 MHz is not covered by this standard.
NOTE Phantom manufacturers are encouraged to extend the frequency range to which phantoms are specified to
enable tests of systems operating at fundamental and harmonic frequencies above 15 MHz.
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 61391-1:2006, Ultrasonics – Pulse-echo scanners – Part 1:Techniques for calibrating
spatial measurement systems and measurement of system point spread function response
IEC 62127-1:2007, Ultrasonics – Hydrophones – Part 1: Measurement and characterization of
medical ultrasonic fields up to 40 MHz
3 Terms and definitions
For the purposes of this document the following terms and definitions apply:
3.1
A-scan
class of data acquisition geometry in one dimension, in which echo strength information is
acquired from points lying along a single beam axis and displayed as amplitude versus time of
flight or distance
[IEC 61391-1:2006, definition 3.1]
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3.2
acoustic scan line (scan line)
one of the component lines which form a B-mode image on an ultrasound monitor, where
each line is the envelope-detected A-scan line in which the echo amplitudes are converted to
brightness values
[IEC 61391-1:2006, definition 3.26]
3.3 acoustic working frequency
arithmetic mean of the frequencies f and f at which the amplitude of the acoustic pressure
1 2
spectrum first falls 3dB below the main peak amplitude.
[IEC 61391-1:2006, definition 3.3, modified]
3.4
attenuation coefficient
at a specified frequency, the fractional decrease in plane wave amplitude per unit path length
in the medium, specified for one-way propagation
–1 –1
Units: m (attenuation coefficient is expressed in dB m by multiplying the fractional
decrease by 8,686 dB.)
NOTE 1 When describing the attenuation properties of a material, the variation of attenuation with frequency
b
should be given. This may be done by expressing a(f), the attenuation coefficient at frequency f, as a(f) = a f ,
o
where f is in MHz, a is the attenuation coefficient at 1 MHz and b is a constant determined by least-squares fitting
o
to experimental data points.
NOTE 2 This parameter specifies the medium’s attenuation only; it excludes reflective losses at interfaces
enclosing the medium and signal decreases due to diffraction.
NOTE 3 See also specific attenuation coefficient.
3.5
B-mode
method of echo-signal display in which the amplitude of the echo signal is represented by
modulation of the brightness of the corresponding point on the display
NOTE The location of the point is determined from the transit time of the acoustic pulse and an assumed value for
sound speed in tissues; for B-mode imaging, it is also determined from the relative position and orientation of the
acoustic scan line.
3.6
B-scan
class of data acquisition geometry in which echo information is acquired from points lying in
an ultrasonic scan plane containing interrogating ultrasonic beams
[IEC 61391-1:2006, definition 3.9]
3.7
backscatter coefficient
at a specified frequency, the mean acoustic power scattered by a specified object in the 180°
direction with respect to the direction of the incident beam, per unit solid angle per unit
volume, divided by the incident beam intensity, the mean power being obtained from different
spatial realizations of the scattering volume
–1 –1
Units: m steradian
NOTE The frequency dependency should be addressed at places where backscatter coefficient is used, if
frequency influences results significantly.
[IEC 61391-1:2006, definition 3.6, modified]
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3.8
backscatter contrast
ratio between the backscatter coefficients of two objects or regions
[IEC 61391-1:2006, definition 3.7, modified]
3.9
beam axis
the longitudinal axis of the pulse-echo response of a given acoustic scan line, a pulse-echo
equivalent to the transmitted beam axis of IEC 62127-1
[IEC 61391-1:2006, definition 3.8, modified]
3.10
digitized image data
two-dimensional set of pixel values derived from the ultrasound echo signals that form an
ultrasound image
3.11
displayed acoustic dynamic range
20 log of the ratio of the amplitude of the maximum echo that does not saturate the display
10
to that of the minimum echo that can be distinguished in the same or similar location of the
display under the scanner test settings
Unit: dB
NOTE On most B-mode scanners echo-signal compression is applied in the receiver, so the displayed acoustic
dynamic range exceeds the input-signal dynamic range capabilities of the monitor.
3.12
display threshold (B-mode)
display luminance just above the luminance when no echo signal is present
3.13
display saturation (B-mode)
display luminance at which an increase in echo-signal level or an increase in system
sensitivity produces no change in luminance
3.14
dynamic range
see local dynamic range; see also displayed dynamic range and global dynamic range
3.15
field-of-view
area in the ultrasonic scan plane from which ultrasound information is acquired to produce
one image frame
NOTE 1 This area can correspond to a two-dimensional or three-dimensional field.
NOTE 2 Definition differs from that of 61391-1 in that it is restricted to the region from which information is
acquired.
[IEC 61391-1:2006, definition 3.13 modified]
3.16
frame rate
number of sweeps comprising the full-frame refresh rate that the ultrasonic beam makes per
second through the field-of-view
[IEC 61391-1:2006, definition 3.14]
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NOTE This parameter usually differs from the image display rate on the scanner monitor.
3.17
gain
ratio of the output to the input of a system, generally an amplifying system, usually expressed
in decibels.
[IEC 61391-1:2006, definition 3.15]
NOTE The ratio applies for a constant and known acoustical system output.
3.18
global dynamic range
ratio of the maximum to the minimum echo-signal amplitude, even with changes of settings,
that a scanner can process without distortion of the output signal
3.19
harmonic imaging
method of imaging in which ultrasound is transmitted at a fundamental frequency and is
detected at harmonic frequencies
NOTE Harmonics are generated by the propagation medium or by nonlinear reflectors. The resulting harmonic
signal is displayed as an image or part of the image.
3.20
local dynamic range
20 log of the ratio, of the minimum echo amplitude that yields the maximum grey level in the
10
digitized image to that of the echo that yields the lowest grey level at the same location in the
image and the same settings
Unit: dB
NOTE 1 For an 8-bit image memory, the maximum gray level in the digitized image will be 255.
NOTE 2 Some documents refer to local dynamic range as the range of echo signals required to vary the display
brightness from barely discernible to maximum brightness at a given location [1]. However, this international
standard applies the name local dynamic range to the digitized image data rather than data viewed on the image
monitor. The name displayed acoustic dynamic range is the equivalent to local dynamic range, but applied to
data viewed on the image monitor.
NOTE 3 This quantity is influenced by the grey scale (dynamic) transfer function associated with the echo display.
3.21
maximum depth of penetration
maximum distance in a tissue-mimicking phantom of specified properties for which the ratio of
the digitized B-mode image data from background scatterers to the digitized B-mode image
data displaying only electronic noise equals 1,4
Unit: m
NOTE The phantom and noise-only images are obtained using identical system settings.
3.22
operating condition
any one of the possible particular control settings for a discrete or a combined operating
mode
3.23
operating mode (d
...
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