Ultrasonics - Real-time pulse-echo scanners - Phantom with cylindrical, artificial cysts in tissue-mimicking material and method for evaluation and periodic testing of 3D-distributions of void-detectability ratio (VDR)

IEC/TS 62558:2011(E) specifies essential characteristics of a phantom and method for the measurement of void-detectability ratio for medical ultrasound systems and related transducers. It is restricted to the aspect of long-term reproducibility of testing results. Medical diagnostic ultrasound systems and related transducers need periodic testing as the quality of medical decisions based on ultrasonic images may decrease over time due to progressive degradation of essential systems characteristics. The TMM (Tissue Mimicking Material) phantom is intended to be used to measure and to enable documentation of changes in void-detectability ratio in periodic tests over years of use. This technical specification establishes:
- Important characteristics and requirements for a TMM 3D artificial cyst phantom using anechoic voids
- A design example of a 3D artificial cyst phantom, the necessary test equipment and use of relevant computer software algorithms.
This technical specification is currently applicable for linear array transducers. A uniformity test prior to void-detectability ratio (VDR) measurement is recommended.

General Information

Status
Published
Publication Date
22-Mar-2011
Technical Committee
Current Stage
PPUB - Publication issued
Start Date
23-Mar-2011
Completion Date
23-Mar-2011
Ref Project

Buy Standard

Technical specification
IEC TS 62558:2011 - Ultrasonics - Real-time pulse-echo scanners - Phantom with cylindrical, artificial cysts in tissue-mimicking material and method for evaluation and periodic testing of 3D-distributions of void-detectability ratio (VDR)
English language
49 pages
sale 15% off
Preview
sale 15% off
Preview

Standards Content (sample)

IEC/TS 62558
Edition 1.0 2011-03
TECHNICAL
SPECIFICATION
colour
inside
Ultrasonics – Real-time pulse-echo scanners – Phantom with cylindrical,
artificial cysts in tissue-mimicking material and method for evaluation and
periodic testing of 3D-distributions of void-detectability ratio (VDR)
IEC/TS 62558:2011(E)
---------------------- Page: 1 ----------------------
THIS PUBLICATION IS COPYRIGHT PROTECTED
Copyright © 2011 IEC, Geneva, Switzerland

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by

any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either IEC or

IEC's member National Committee in the country of the requester.

If you have any questions about IEC copyright or have an enquiry about obtaining additional rights to this publication,

please contact the address below or your local IEC member National Committee for further information.

Droits de reproduction réservés. Sauf indication contraire, aucune partie de cette publication ne peut être reproduite

ni utilisée sous quelque forme que ce soit et par aucun procédé, électronique ou mécanique, y compris la photocopie

et les microfilms, sans l'accord écrit de la CEI ou du Comité national de la CEI du pays du demandeur.

Si vous avez des questions sur le copyright de la CEI ou si vous désirez obtenir des droits supplémentaires sur cette

publication, utilisez les coordonnées ci-après ou contactez le Comité national de la CEI de votre pays de résidence.

IEC Central Office
3, rue de Varembé
CH-1211 Geneva 20
Switzerland
Email: inmail@iec.ch
Web: www.iec.ch
About IEC publications

The technical content of IEC publications is kept under constant review by the IEC. Please make sure that you have the

latest edition, a corrigenda or an amendment might have been published.
 Catalogue of IEC publications: www.iec.ch/searchpub

The IEC on-line Catalogue enables you to search by a variety of criteria (reference number, text, technical committee,…).

It also gives information on projects, withdrawn and replaced publications.
 IEC Just Published: www.iec.ch/online_news/justpub

Stay up to date on all new IEC publications. Just Published details twice a month all new publications released. Available

on-line and also by email.
 Electropedia: www.electropedia.org

The world's leading online dictionary of electronic and electrical terms containing more than 20 000 terms and definitions

in English and French, with equivalent terms in additional languages. Also known as the International Electrotechnical

Vocabulary online.
 Customer Service Centre: www.iec.ch/webstore/custserv

If you wish to give us your feedback on this publication or need further assistance, please visit the Customer Service

Centre FAQ or contact us:
Email: csc@iec.ch
Tel.: +41 22 919 02 11
Fax: +41 22 919 03 00
---------------------- Page: 2 ----------------------
IEC/TS 62558
Edition 1.0 2011-03
TECHNICAL
SPECIFICATION
colour
inside
Ultrasonics – Real-time pulse-echo scanners – Phantom with cylindrical,
artificial cysts in tissue-mimicking material and method for evaluation and
periodic testing of 3D-distributions of void-detectability ratio (VDR)
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
PRICE CODE
ICS 17.140.50 ISBN 978-2-88912-377-3
® Registered trademark of the International Electrotechnical Commission
---------------------- Page: 3 ----------------------
– 2 – TS 62558  IEC:2011(E)
CONTENTS

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

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

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

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

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

4 Symbols ......................................................................................................................... 11

5 Ambient conditions of measurement with the phantom .................................................... 12

6 Specification of TMM 3D artificial anechoic-cyst phantom ............................................... 12

6.1 3D-phantom concept ............................................................................................. 12

6.2 General phantom specification .............................................................................. 12

6.3 TMM specifications: ............................................................................................... 12

6.4 Anechoic targets ................................................................................................... 13

6.5 Phantom enclosure................................................................................................ 13

6.6 Scanning surface: ................................................................................................. 13

6.7 Dimensions ........................................................................................................... 13

6.8 Phantom stability ................................................................................................... 14

6.9 Digitized image data .............................................................................................. 14

7 Principle of measurement using the 3D anechoic void phantom ...................................... 15

7.1 General ................................................................................................................. 15

7.2 Analysis ................................................................................................................ 15

Annex A (informative) Description of construction of an example phantom and test

results .................................................................................................................................. 17

Annex B (informative) System description ............................................................................ 37

Annex C (informative) Rationale .......................................................................................... 38

Annex D (informative) Uniformity measurement ................................................................... 41

Bibliography .......................................................................................................................... 48

Figure A.1 – Example of measurement test equipment .......................................................... 17

Figure A.2a) – Package of TMM slices containing alternating void slices and

attenuation slices of polyurethane foam ................................................................................ 19

Figure A.2b) – Holes of different diameters in the void slices allow the use of the

phantom with different ultrasound frequencies (1 – 15 MHz) ................................................. 19

Figure A.2 – TMM slices ....................................................................................................... 19

Figure A.3 – Structure of foam .............................................................................................. 19

Figure A.4 – C-images of voids ............................................................................................. 20

Figure A.5 – Experimental confirmation of Rayleigh distribution with attenuating TMM .......... 21

Figure A.6 – Speed of sound in saltwater .............................................................................. 22

Figure A.7 – Phantom with motor drive and two types of adapters ........................................ 22

Figure A.8 – B-, D-, C- images and grey scale ...................................................................... 24

Figure A.9 – Illustration of the VDR calculation for a ROI consisting of a single line .............. 25

Figure A.10 – B-C-D planes .................................................................................................. 26

Figure A.11 – Principle of the ultrasound scanning array and beam ...................................... 27

Figure A.12 – Schematic of B-D-C planes ............................................................................. 28

---------------------- Page: 4 ----------------------
TS 62558  IEC:2011(E) – 3 –

Figure A.13 – 3D-Phantom images ....................................................................................... 29

Figure A.14 – B-D-C images and VDR .................................................................................. 30

Figure A.15a) – Example: Curved Array, 40-mm radius, 3,5MHz with good VDR-values. ....... 31

Figure A.15b) – Example: Curved Array, 40-mm radius, 3,5MHz with poor VDR-values ........ 31

Figure A.15 – VDR-values .................................................................................................... 31

Figure A.16 – Example: Linear array transducer 13 MHz ....................................................... 32

Figure A.17 – Interpretation of VDR parameter ..................................................................... 33

Figure A.18 – Explanation of saturation (0-255 grey-scale range) ......................................... 34

Figure A.19a) – Voids 2,5 mm ............................................................................................... 35

Figure A.19b) – Voids 3,0 mm ............................................................................................... 35

Figure A.19c) – Voids 4 ;0 mm .............................................................................................. 35

Figure A.19 – Saturation effect ............................................................................................. 35

Figure A.20 – Void spot analysis ........................................................................................... 35

Figure A.21a) – Local dynamic curve .................................................................................... 36

Figure A.21b) – Expected envelope of VDR .......................................................................... 36

Figure 21 – Local dynamic range .......................................................................................... 36

Figure C.1 – Autocorrelation function .................................................................................... 39

Figure C.2a) – Autocorrelation function at 4,06 cm depth ...................................................... 40

Figure C.2b) – Autocorrelation function at 9,08 cm depth ...................................................... 40

Figure C.2 – Autocorrelation function – dependence on depth .............................................. 40

Figure C.3 – Autocorrelation function at 10,94 cm depth ....................................................... 40

Figure D.1a) – Uniformity test with related linear or curved array transducer ......................... 42

Figure D.1b) – Fixed pattern in B-image ............................................................................... 42

Figure D.1 – Uniformity test .................................................................................................. 42

Figure D.2a) – B-D-C image and fixed pattern in C-image ..................................................... 43

Figure D.2b) – Grey scale display of full array ...................................................................... 43

Figure D.2 – Uniformity test – Additional features ................................................................. 43

Figure D.3 – Linear transducer with reference tape ............................................................... 44

Figure D.4 – Interpretation of simulated transducer failure when half of the probe is

covered by five layers of 50-mm fabric tape .......................................................................... 45

Figure D.5 – Disconnected elements, example with linear transducer ................................... 46

Figure D.6 – Example with curved array transducer and reference tape ................................ 47

---------------------- Page: 5 ----------------------
– 4 – TS 62558  IEC:2011(E)
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ULTRASONICS – REAL-TIME PULSE-ECHO SCANNERS –
PHANTOM WITH CYLINDRICAL, ARTIFICIAL CYSTS IN TISSUE-MIMICKING
MATERIAL AND METHOD FOR EVALUATION AND PERIODIC TESTING
OF 3D-DISTRIBUTIONS OF VOID-DETECTABILITY RATIO (VDR)
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.

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

exceptional circumstances, a technical committee may propose the publication of a technical

specification when

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

despite repeated efforts, or

• 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 62558, which is a technical specification, has been prepared by IEC technical committee

87: Ultrasonics.
---------------------- Page: 6 ----------------------
TS 62558  IEC:2011(E) – 5 –
The text of this technical specification is based on the following documents:
Enquiry draft Report on voting
87/434/DTS 87/458/RVC

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

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

the stability date indicated on the IEC web site under "http://webstore.iec.ch" in the data

related to the specific publication. At this date, the publication will be
• transformed into an International standard,
• 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

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

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

colour printer.
---------------------- Page: 7 ----------------------
– 6 – TS 62558  IEC:2011(E)
INTRODUCTION

This technical specification provides an example of a measurement method and of a test

phantom. The specified method and test equipment permit operation without knowledge of

proprietary information of the diagnostic ultrasonic equipment manufacturer.
This technical specification describes desirable specifications and performance

characteristics of a tissue-mimicking material (TMM) 3D artificial-cyst phantom. An example

including design of a realized and conforming phantom is given. The described results are

independent of applied electronic and design architecture of diagnostic ultrasound systems

and related transducers suitable for testing with the phantom.

Medical diagnostic ultrasound systems and related transducers need periodic testing as the

quality of medical decisions based on ultrasonic images may decrease over time due to

progressive degradation of essential systems characteristics. The TMM phantom is intended

to be used to measure and to enable documentation of changes in void-detectability ratio in

periodic tests over years of use.

The example of phantom design uses sliced TMM arranged as alternating "cyst-slices" and

"attenuation-slices". It allows measurement along all three axes of the ultrasonic beam (axial,

azimuthal and elevation) to determine the void-detectability ratio depending on the depth in

the image generated from a transducer. The basis of the design concept and measurement

method is anechoic, artificial cysts, representing idealized pancreatic ducts in the human

body, and the measurement of the void-detectability ratio inside the images of these artificial

cysts. The images of the artificial cysts should appear anechoic. The measurement of void-

detectability ratio quantifies the diagnostic ultrasound system’s ability to properly represent

these objects. Increased artifactual signals appearing within images of these artificial cysts

indicate a degradation of certain image parameters. A certain level of artifactual signals is to

be expected for any ultrasound system, due to the emitted beam's shape and the transducer's

receive characteristics. Any increase in these artifactual signals may be caused, for example,

by grating- and side-lobes that may occur due to, for example, partial or total depolarisation of

elements, delamination between transducer elements and lens, or corrosion. The

measurement procedure allows a reliably and reproducible determination of the visibility limits

of small voids, an important image parameter of an ultrasound diagnostic system over the

time of use, by applying dedicated acquisition, processing and documentation software.

Four informative annexes are provided: Annex A – Description of construction of an example

phantom and test results; Annex B – System description; Annex C – Rationale; Annex D –

Uniformity measurement.
---------------------- Page: 8 ----------------------
TS 62558  IEC:2011(E) – 7 –
ULTRASONICS – REAL-TIME PULSE-ECHO SCANNERS –
PHANTOM WITH CYLINDRICAL, ARTIFICIAL CYSTS IN TISSUE-MIMICKING
MATERIAL AND METHOD FOR EVALUATION AND PERIODIC TESTING
OF 3D-DISTRIBUTIONS OF VOID-DETECTABILITY RATIO (VDR)
1 Scope

This technical specification specifies essential characteristics of a phantom and method for

the measurement of void-detectability ratio for medical ultrasound systems and related

transducers. It is restricted to the aspect of long-term reproducibility of testing results.

This technical specification establishes:

– important characteristics and requirements for a TMM 3D artificial cyst phantom using

anechoic voids;

– a design example of a 3D artificial cyst phantom, the necessary test equipment and use of

relevant computer software algorithms.

This technical specification is currently applicable for linear array transducers. A uniformity

test prior to void-detectability ratio (VDR) measurement is recommended.

NOTE The basic concept of the 3D artificial-cyst phantom may also be valid for other types of ultrasound

transducers; however there is a need for further verification (see Annex D).
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 amendments) applies.
IEC 60050-802, International Electrotechnical Vocabulary, Part 802: Ultrasonics
3 Terms and definitions

For the purposes of this document, the terms and definitions contained in IEC 60050-802 as

well as the following terms and definitions apply.
3.1
acoustic coupling medium

medium, usually fluid or a gel, that allows echo-free coupling of the transducer to the coupling

window of the phantom.
3.2
artifactual signal

signal at a specific region in an image where no signal is expected (e.g. inside the image of a

void)
3.3
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
---------------------- Page: 9 ----------------------
– 8 – TS 62558  IEC:2011(E)
–1 –1

Units: m (attenuation coefficient is expressed in dB m by multiplying the fractional

decrease by 8,686 dB)
[IEC 61391-2:2010, definition 3.4]
3.4
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
steradian
Units: m

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]
3.5
backscatter contrast
ratio between the backscatter coefficients of two objects or regions
[IEC 61391-2:2010, definition 3.8]

NOTE Backscatter contrast can be frequency-dependent but it is independent of any image system.

3.6
B-, C-, D-image
basic cross sectional presentations of 3D-images:
B-image is in a plane that is created by the acoustic scan-lines (scan plane);
C-image is in a plane perpendicular to the acoustic scan lines in the B-image;
D-image is in a plane perpendicular to B-image–plane and C-image-plane
3.7
B-, C-, D-(image) plane
B-plane: scan plane;

C-plane: reconstructed image plane that is perpendicular to acoustic scan lines in the B-

plane;

D-plane: reconstructed image plane that is perpendicular to the scan plane and the C-plane

3.8
coupling window

portion of the phantom’s enclosure provided for entrance and exit of the transmitted

ultrasound waves to/from the tissue-mimicking material without significant attenuation or

distortion

NOTE The coupling window usually consists of a thin membrane which protects the tissue-mimicking material

from evaporation, leakage and mechanical damage by the transducer and which does not significantly alter the

ultrasound signals
3.9
detection limit

smallest true value of the measurement, which is detectable by the measuring method

[IEC 60761-1:2002, definition 3.10, modified]
---------------------- Page: 10 ----------------------
TS 62558  IEC:2011(E) – 9 –
3.10
digitized image data

two-dimensional or three-dimensional set of pixel (voxel) values derived from the grey-level

values of the B-mode images that are sent to the monitor screen
3.11
documentation
human-readable information about a device instance
[IEC 62453-1:2009, definition 3.1.18]

NOTE Within the context of this TS, the printed documentation and the documentation provided via Extended

Markup Language (XML) are also meant. The documentation can consist of several documents and images.

3.12
fixed pattern

parts of the B-mode image that remain in the same position relative to the image frame when

the transducer is moved
3.13
grey-level value

number determining the brightness of the pixels of a B-mode image (as derived from the

signal amplitude of the signal reflected from the corresponding position in the body)

NOTE The grey level values determine the brightness of specific pixels in the image and they historically range

from 0 (black) to 255 (white). Black indicates a weak signal, white a strong signal, This convention holds

throughout this document for calculations. In images an inverted display can be used, where black

indicates the level 256 and white 0.
3.14
(acoustic) scan line

one of the component lines that form a B-mode image on an ultrasound system 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, modified]
3.15
scan plane
acquired image plane containing the acoustic scan lines
[IEC 61391-2:2010, definition 3.30]
3.16
specific attenuation coefficient

at a specified frequency, the slope of attenuation coefficient plotted against frequency

–1 –1
Units: m Hz
3.17
Tissue-mimicking material
TMM

material in which the propagation velocity (speed of sound), reflection, scattering, and

attenuation properties are similar to those of soft tissue for ultrasound in the frequency range

1 MHz to 15 MHz
[IEC 61391-1:2006, 3.36, modified]
---------------------- Page: 11 ----------------------
– 10 – TS 62558  IEC:2011(E)
3.18
TMM 3D artificial anechoic cyst phantom

phantom containing tissue-mimicking material, in which there are well-defined regions whose

backscatter contrast is lower than -60 dB relative to the regions containing TMM
3.19
uniformity test procedure

procedure to test the uniformity of the transmitted signals of all the elements of array

transducers
3.20
void
artificial anechoic cyst

region of defined geometry in a tissue-mimicking material that generates no scattered

acoustic waves

NOTE Saline solution in specified concentration is known to produce extremely low levels of scattered signals and

therefore it is an optimal approximation to a perfect void.
3.21
void-detectability ratio
VDR

number characterizing the visibility of an image area corresponding to a void of defined

diameter surrounded by tissue-mimicking material (TMM) in the phantom
VDR = (µ - µ ) / σ = (1/n)(Σ (VDR ))
1 2 1 i=1..n i
where

µ = mean image pixel value of the TMM in the region surrounding the void for a given

C-plane;

µ = mean value of the image pixel values from within the image area representing a void;

σ = standard deviation of mean pixel values over separate TMM areas equal to the void

area and lying in the region of the void, for a given C-plane;

n = number of voxels (pixels) from a given C-plane or from a specific part of this C-plane

(e.g. the image area of a single void or the image area of all voids within the C-plane)

NOTE 1 The image of the surrounding TMM material is expected to show modulated grey levels (i.e. an

ultrasound speckle image) due to the ultrasound interference patterns).
NOTE 2: The VDR formula is derived from [4]
3.21.1
detectability ratio for a single voxel
detectability ratio for a single voxel is defined by:
VDR = (µ - g ) / σ
i 1 i 1
where

µ = mean image pixel value of the TMM in the region surrounding the void for a given C-

plane;

g = grey level value of the i-th voxel (pixel) from a given C-plane or from a specific part of

this C-plane (e.g. the image area of a single void or the image area of all voids within

the C-plane);

σ = standard deviation of mean pixel values over separate TMM areas equal to the void

area and lying in the region of the void, for a given C-plane
...

Questions, Comments and Discussion

Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.