Iec ts 62736 2016

I E C TS 62 ® Edition 201 6-07 TE C H N I C AL S P E C I F I C ATI ON colour in sid e U l tras on i cs – P u l s e-ech o s can n ers – S i m pl e m eth od s for peri od i c tes ti n g to veri fy s tabi l i ty of an i m ag i n g s ys tem ’ s IEC TS 62736:201 6-07(en) el em en tary perform an ce Copyright International Electrotechnical Commission TH I S P U B L I C ATI O N I S C O P YRI G H T P RO TE C T E D C o p yri g h t © I E C , G e n e va , S w i tze rl a n d 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 IEC Central Office 3, rue de Varembé CH-1 21 Geneva 20 Switzerland Tel.: +41 22 91 02 1 Fax: +41 22 91 03 00 info@iec.ch www.iec.ch Abou t th e I E C The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes International Standards for all electrical, electronic and related technologies Ab o u t I E C p u b l i c a ti o n s 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 I E C C atal og u e - webs tore i ec ch /catal og u e E l ectroped i a - www el ectroped i a org The stand-alone application for consulting the entire bibliographical information on IEC International Standards, Technical Specifications, Technical Reports and other documents Available for PC, Mac OS, Android Tablets and iPad The world's leading online dictionary of electronic and electrical terms containing 20 000 terms and definitions in English and French, with equivalent terms in additional languages Also known as the International Electrotechnical Vocabulary (IEV) online I E C pu bl i cati on s s earch - www i ec ch /s earch pu b I E C G l os s ary - s td i ec ch /g l os s ary The advanced search enables to find IEC publications by a variety of criteria (reference number, text, technical committee,…) It also gives information on projects, replaced and withdrawn publications 65 000 electrotechnical terminology entries in English and French extracted from the Terms and Definitions clause of IEC publications issued since 2002 Some entries have been collected from earlier publications of IEC TC 37, 77, 86 and CISPR I E C J u st P u bl i s h ed - webs tore i ec ch /j u s u bl i s h ed Stay up to date on all new IEC publications Just Published details all new publications released Available online and also once a month by email Copyright International Electrotechnical Commission I E C C u s to m er S ervi ce C en tre - webs tore i ec ch /cs c If you wish to give us your feedback on this publication or need further assistance, please contact the Customer Service Centre: csc@iec.ch I E C TS 62 ® Edition 201 6-07 TE C H N I C AL S P E C I F I C ATI ON colour in sid e U l tras on i cs – P u l s e-ech o s can n ers – S i m pl e m eth od s for peri od i c tes ti n g to veri fy s tabi l i ty of an i m ag i n g s ys tem ’ s el em en tary perform an ce INTERNATIONAL ELECTROTECHNICAL COMMISSION ICS 7.1 40.50 ISBN 978-2-8322-3529-4 Warn i n g ! M ake s u re th at you obtai n ed th i s pu bl i cati on from an au th ori zed d i s tri bu tor ® Registered trademark of the International Electrotechnical Commission Copyright International Electrotechnical Commission –2– I EC TS 62736:201 © IEC 201 CONTENTS FOREWORD I NTRODUCTI ON Scope Normative references Terms and definitions General recommendation Environmental conditions Quality control levels General Level tests Level tests 1 Level tests 1 Equipment and data required General Phantoms 2.1 Phantoms for Level and/or Level quality control 2.2 Phantoms for Level quality control only 2.3 Phantoms for both Level and Level quality control I mage data 3.1 Digital-image data 3.2 I mage-archiving systems Expectations of system suppliers Level test methods Level measurement methods Mechanical inspection I mage uniformity for transducer element and channel integrity 2.1 General 2.2 Apparatus scanning procedures and system settings 2.3 I mage acquisition 2.4 Analysis Level measurement methods 20 0.1 General 20 0.2 Maximum relative depth of penetration 20 0.2.1 Assessment 20 0.2.2 Scanning system settings 20 0.2.3 I mage acquisition 21 0.2.4 Analysis 22 0.2.5 Commentary 23 0.3 System-image display 23 0.3.1 General 23 0.3.2 Level tests of the U S-system and interpretation-station display 23 0.3.3 Level and tests 23 0.4 Distance measurements for mechanically scanned distances 24 0.4.1 General 24 0.4.2 Apparatus and scanning system settings 25 Copyright International Electrotechnical Commission I EC TS 62736:201 © IEC 201 –3– I mage acquisition 25 0.4.3 0.4.4 Analysis 25 Annex A (informative) Example phantoms for image uniformity and/or maximum relative depth of penetration 26 Annex B (informative) Available analysis software 29 B Open source software for assessment for QC of ultrasound image uniformity 29 B Example of QC control chart: 31 Annex C (informative) Display test patterns 33 Annex D (informative) Electronic test methods and test methods provided by the manufacturers; relation to clinical significance 35 Bibliography 36 Figure – Median-averaged image (right) and its lateral profile (left) Figure – A) I mage of a uniform section in a tissue-mimicking phantom, bright rectangle; B) I mage displaying electronic noise only, obtained with the operating controls set the same as for A but with the transducer decoupled from the phantom [SOURCE: University of Wisconsin] 21 Figure – Mean digitized image-data value vs depth for the phantom image data ( A ( j )) and for the noise-image data ( A j)) 22 Figure A.1 – Example phantom for image-uniformity and/or maximum-relative-depthof-penetration tests 26 Figure A.2 – Example compact phantom for image-uniformity tests 27 Figure A.3 – Photograph and drawing of a three-in-one phantom which provides for determination of distance measurement precision and bias, image uniformity and depth of penetration [37] 27 Figure A.4 – A compact uniformity phantom of relatively durable rubber material 28 Figure B.1 – On the left the profile of median pixel value is plotted for each image column in the analysis box shown in the median image on the right for the transducer in Figure , but without the nylon filament obstructing some central elements 30 Figure B.2 – Control chart for a dip in the middle of the profile for one transducer (TD) mode C9-4 and the specified serial number (S/N) 32 Figure C – AAPM TG1 8-UN1 (left) and TG1 8-UN80 (right) patterns for luminance uniformity, colour uniformity, and angular response evaluations [35] 33 Figure C – Example data entry form for visual display evaluation: left for Figure C ; right for Figure C.3 34 Figure C – TG1 8-CT low-contrast test pattern for the evaluation of the luminance response of display systems [35] 34 ʹ( Table – Outline of Level tests Table – Outline of Level tests additional to those in Table 1 Table B.1 – Output of analysis 31 Copyright International Electrotechnical Commission –4– I EC TS 62736:201 © IEC 201 I NTERNATIONAL ELECTROTECHNI CAL COMMI SSI ON U L T RAS O N I C S – P U L S E - E C H O S C AN N E RS – S i m p l e m e t h o d s fo r p e ri o d i c t e s ti n g to v e ri fy s t a b i l i t y o f a n i m a g i n g s ys t e m ’ s e l e m e n t a ry p e rfo rm a n c e FOREWORD ) The I ntern ati onal El ectrotechnical Commi ssi on (I EC) is a worl d wid e org anizati on for standard izati on comprisi ng all nati onal electrotech nical committees (I EC N ational Comm ittees) Th e object of I EC i s to promote i nternati on al co-operati on on al l q u esti ons cernin g standard izati on i n the el ectrical and el ectronic fi el ds To this end an d in ad di ti on to other acti vi ti es, I EC pu blish es I nternati onal Stand ards, Technical Speci fi cati ons, Technical Reports, Pu blicl y Availabl e Specificati ons (PAS) an d Gu id es (hereafter referred to as “I EC Pu blicati on(s)”) Their preparati on is entru sted to techni cal committees; any I EC N ati onal Committee i nterested i n the subject d eal t wi th may parti ci pate i n thi s preparatory work I nternati onal , governmental and n ongovernm ental organizations l iaisi ng wi th the I EC al so participate i n this preparati on I EC coll aborates cl osel y wi th th e I n ternational Organizati on for Stand ard izati on (I SO) i n accordan ce wi th cond i ti ons d etermined by agreement between th e two org anizati ons 2) Th e form al d ecision s or ag reements of I EC on technical m atters express, as n earl y as possibl e, an i nternati onal consensus of opi ni on on the rel evan t su bjects si nce each technical committee has representati on from all i nterested I EC N ati onal Commi ttees 3) I EC Pu blications have th e form of recommend ati ons for internati onal u se and are accepted by I EC N ati onal Comm ittees i n th at sense While all reasonabl e efforts are mad e to ensu re that the technical content of I EC Pu blicati ons is accu rate, I EC cann ot be hel d responsi bl e for th e way in wh i ch they are used or for an y misin terpretati on by any end u ser 4) I n ord er to promote i nternational u ni formi ty, I EC N ati onal Commi ttees u nd ertake to appl y I EC Publicati on s transparen tl y to the maximum extent possibl e i n thei r nati on al and regi on al pu blicati ons Any d i vergence between an y I EC Pu bl icati on and the correspond i ng nati onal or region al publi cation shal l be cl earl y i ndi cated in the l atter 5) I EC i tsel f d oes not provi d e any attestation of conformity I nd epen d ent certi ficati on bodies provi d e conformity assessment services and , in some areas, access to I EC m arks of conformi ty I EC i s not responsible for any services carried ou t by i nd epend ent certi fication bodi es 6) All users should ensu re that they have the l atest edi ti on of this pu blicati on 7) N o li abili ty shal l attach to I EC or i ts di rectors, empl oyees, servants or agen ts incl u di ng i nd ivi d u al experts and m embers of i ts tech ni cal comm ittees and I EC N ati onal Committees for any personal i nju ry, property d amag e or other d amage of any natu re whatsoever, whether di rect or i nd i rect, or for costs (i nclud in g l egal fees) and expenses arising ou t of th e pu bli cati on , use of, or rel iance u pon, thi s I EC Pu bl ication or any oth er I EC Pu blicati ons 8) Attention is d rawn to the N ormative references ci ted i n this pu bl icati on U se of the referenced pu blicati ons is i nd i spensabl e for th e correct appli cati on of this pu blicati on 9) Attention is d rawn to the possibili ty th at some of the el em ents of thi s I EC Pu bl icati on may be the su bj ect of paten t ri ghts I EC shal l n ot be held responsi bl e for i d enti fyi ng any or all such paten t ri gh ts The main task of I EC technical committees is to prepare International Standards I n 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 I nternational 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 I nternational Standards I EC TS 62736, which is a Technical Specification, has been prepared by I EC technical committee 87: U ltrasonics Copyright International Electrotechnical Commission I EC TS 62736:201 © IEC 201 –5– The text of this Technical Specification is based on the following documents: En q ui ry d raft Report on voti ng 87/576/DTS 87/592A/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/I EC Directives, Part Terms in bol d Roman italic in the text are defined in Clause Symbols and formulae are in Times New The committee has decided that the contents of this publication will remain unchanged until the stability date indicated on the I EC website 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 I M P O R T AN T – T h e ' c o l o u r i n s i d e ' th a t it c o n ta i n s u n d e rs t a n d i n g c o l o u r p ri n t e r Copyright International Electrotechnical Commission of c o l o u rs i ts wh i ch c o n te n ts l og o a re U s e rs on th e c o ve r p a g e o f th i s c o n s i d e re d shou l d to t h e re fo re be p u b l i ca ti o n u s e fu l p ri n t th i s fo r i n d i c a te s th e d o cu m e n t c o rre c t using a –6– I EC TS 62736:201 © IEC 201 I NTRODUCTION 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 U ltrasonic scanners are widely used in medical practice to produce images of soft-tissue organs throughout the human body As ultrasound systems are usually employed under rigorous time restrictions and in diverse environments to help make decisions often critical to patients’ well being, it is important that the systems perform consistently at the level provided and accepted in initial tests, e g those of I EC 61 391 -1 and I EC 61 391 -2 This document provides methods to verify the stability of an imaging system’s elementary performance This document is deemed necessary because substandard ultrasound system performance is often accepted, or remains undetected in the absence of unequivocal and documented tests The most common of the failures, in all but the oldest systems nearing retirement, are subperformance of a transducer-array element or lens or of a cable or electronic channel Sensitive image uniformity tests for these transducer- and channel-failures are presented in this document for use monthly (Level ), biannually (Level 2) and biennially (Level 3) With approximately % transducer-failure rate and % system-failure rate per year on first testing [1 ], [2], [3], [4], [5],[6], [7],[8], [9], [1 0], [1 ], [1 2], there are, very approximately, 00 000 systems worldwide routinely performing suboptimal diagnostic exams for part of the year   This common occurrence of suboptimal diagnostic examinations has created an urgent need to standardize quality-control (QC) and performance-evaluation procedures to promote improved efficacy of diagnostic examinations through widespread use of effective QC procedures and to dispel myths as to their utility Proposers believe, however, that existing national standards and guides [1 3],[1 4] specify too many tests and inappropriate tests for detecting and discriminating the common flaws in diagnostic ultrasound systems during routine QC These practices include tests, such as spatial resolution, which are low-yield and belong in performance-evaluation procedures, rather than QC Modern flat-panel display technology is more stable than, and generally far superior to, earlier CRT displays H owever, LCD displays can still exhibit luminance drift, as well as problems such as defective pixels I t is still necessary to evaluate them periodically Copyright International Electrotechnical Commission I EC TS 62736:201 © IEC 201 –7– U L T RAS O N I C S – P U L S E - E C H O S C AN N E RS – S i m p l e m e t h o d s fo r p e ri o d i c t e s t i n g to v e ri fy s t a b i l i t y o f a n i m a g i n g s ys t e m ’ s e l e m e n t a ry p e rfo rm a n c e Scope This document specifies requirements and methods for periodic testing of the quality of diagnostic medical ultrasound systems with linear array, curved linear array, single element, annular array, phased array, matrix linear array transducers and two-dimensional arrays I mage interpretation and measurement workstations are included Usually, “periodic testing” is referred to here as “quality control” This document represents a minimum set of such tests intended for frequent users of medical ultrasound systems, for quality control professionals in their organization, or those hired from other quality-control and/or service-provider organizations System-manufacturing and repair companies might well employ other or additional tests The tests are defined in three levels, with the simplest and most costeffective performed most frequently, similarly to [1 ] More complete tests for acceptance testing and for assessment at times of particular importance or concern are specified in I EC 61 391 -1 , I EC 61 391 -2 and IEC TS 62791 [1 5] These more complete tests are categorized as performance evaluation, rather than quality control or frequent periodic testing This document also defines terms and specifies methods for measuring (for quality maintenance or quality control) the of real-time ultrasound B-MODE scanners, though this penetration measure is listed as less frequently applied m a xi m u m re l a t i ve d e p th of p e n e t t i o n Frequent distance-measurement accuracy tests are recommended only for certain classes of position encoding that are not now known to be highly stable and without bias 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 Transducers not readily amenable to transducer-element testing by the simple imageuniformity procedures specified (for example, phased array and 2D-array transducers) are tested only partially by maximum relative depth of penetration System manufacturers are encouraged to provide pulsing patterns of the transducer elements to allow testing of individual elements or small-enough groups of elements to enable users to detect significant element failure or to provide access to another implemented and explained element-test program Dedicated Doppler systems are excluded from coverage here as specialized equipment is required to test them This test equipment can be specific to the intended application of the Doppler system All scanners considered include basic pulse-echo techniques The failures to be detected by the recommended pulse-echo tests also will affect the operation of other modes, such as colour-flow, harmonic-, elasticity- and compound imaging The test methodology is applicable for transducers operating in the MHz to MHz frequency range and could be made applicable up to 40 MHz, if the depth of penetration were allowed to be relative, rather than Copyright International Electrotechnical Commission –8– I EC TS 62736:201 © IEC 201 absolute, and phantom stability were verified [1 5] I mage-uniformity QC is applicable to transducers operating in the MHz to 40 MHz frequency range as the requirements for phantoms are not stringent N OTE Phantom manu factu rers are en cou raged to extend the freq u ency range to wh i ch ph antoms are speci fi ed to enable rel ative d epth-of-penetration tests of systems operati ng at fu nd tal and harmon ic freq u encies above M H z Normative references The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document For dated references, only the edition cited applies For undated references, the latest edition of the referenced document (including any amendments) applies IEC 60050-802, In te rn a tion a l < http://www.electropedia.org > ) I EC 61 391 -1 , Electrotech n ica l Voca bula ry – Pa rt 802: Ultra son ics (available at Ultra son ics – Pulse -e ch o sca n n e rs – Pa rt : Tech n iques for ca libra tin g spa tia l me a sure men t syste ms a n d me a sure me n t of syste m p oin t spre a d fun ction respon se I EC 61 391 -2, Ultra son ics – Pulse -ech o sca n n e rs – Pa rt 2: Mea sure me n t of ma ximum de p th of pe n e tra tion a n d loca l dyn a mic n ge Terms and definitions For the purposes of this document, the terms and definitions given in IEC 60050-802 and the following apply I SO and I EC maintain terminological databases for use in standardization at the following addresses: • • I EC Electropedia: available at http: //www.electropedia.org/ I SO Online browsing platform: available at http: //www iso.org/obp 3.1 addressable patch smallest addressable group of transducer elements 3.2 echo from weakly reflecting, background scatterers echoes from many small targets in which the scattered field is much less intense than the incident field 3.3 maximum depth of penetration maximum range at which the ratio of the mean, digitized, B-mode-image data corresponding to images displaying echoes from weakly reflecting, background scatterers to the mean, digitized, B-mode-image data corresponding to images displaying only electronic noise equals , 4, when the echoes from weakly reflecting, background scatterers are generated in a phantom with properties meeting the specifications of I EC 61 391 -2 N ote to en try: The maxi m um depth of penetrati on is expressed i n metres (m) and conventi onall y i n centi metres (cm) Copyright International Electrotechnical Commission – 26 – I EC TS 62736:201 © IEC 201 Annex A (informative) Example phantoms for image uniformity and/or maximum relative depth of penetration A phantom for linear arrays and curved-linear arrays for image-uniformity tests and allowing for the optional relative-depth-of-penetration measures is illustrated in Figure A This phantom is a solid block of urethane with a homogeneous distribution of scatterers The cmwide well in the top aids coupling of curved-linear arrays A less expensive and more compact phantom, probably of similar materials, except high attenuation to avoid reverberations, is shown in Figure A.2 Two circular wells are shown for scanning by rotation of the transducer rather than a linear sweep The large and small wells are for slightly and tightly curved linear arrays, respectively A versatile phantom is shown in Figure A.3 and a temporally stable, inexpensive one in Figure A.4 For more rigorous measurements, with less chance of acoustic-contact problems [3], scatterers in a constantly stirred liquid can be employed No scanning motion is required The transducer is lowered into the liquid the minimum distance to establish good acoustic contact and cine loops are acquired Rad iu s of cu rvatu re, 1 cm cm ∼ cm cm 20 cm 25 cm IEC Figure A.1 – Example phantom for image-uniformity and/or maximum-relative-depth-of-penetration tests Copyright International Electrotechnical Commission I EC TS 62736:201 © IEC 201 – 27 – cm cm cm Concave rad iu s of cu rvatu re, 1 cm Rad i us of cu rvatu re, cm cm cm cm , cm IEC Figure A.2 – Example compact phantom for image-uniformity tests Proxi m al an d d istal en d s of scan n i n g wi n d ow for smal ler ROCs cm IEC cm × cm fl at scannin g win d ow 7, cm × cm flat scann ing wi nd ow Proxi mal an d d i stal en d s of scan n in g wi n d ow for l arg er ROCs Th ree-i n-on e ph an tom en d vi ew with wi nd ow for 0, cm to cm ROCs u pward IEC Key ROC rad i us of cu rvatu re Figure A.3 – Photograph and drawing of a three-in-one phantom which provides for determination of distance measurement precision and bias, image uniformity and depth of penetration [37] Two cone-shaped scanning windows are on opposite sides; together the two windows allow direct contact of convex (curved) arrays with any radius of curvature (ROC) from 3, cm through cm The scanning window that accommodates ROCs from cm through cm is directed upward in the photograph; the windows have a metallic appearance because they consist of plastic-coated aluminium foil, which transmits the ultrasound beam but suppresses Copyright International Electrotechnical Commission – 28 – I EC TS 62736:201 © IEC 201 desiccation of the tissue-mimicking phantom material The cork layers are for preventing sliding of the phantom when on a smooth surface A third flat scanning window is shown on the side of the phantom for accommodating other transducer shapes such as linear arrays and phased arrays Figure A depicts a uniformity phantom of rubber material flexible enough to fit many transducer shapes, but too flexible for built-in distance calibration points or filaments unless a rigid plate with ridges were attached to the bottom and right end This phantom would serve better if a bit thicker IEC Figure A.4 – A compact uniformity phantom of relatively durable rubber material Copyright International Electrotechnical Commission I EC TS 62736:201 © IEC 201 – 29 – Annex B (informative) Available analysis software B.1 Open source software for assessment for QC of ultrasound image uniformity Some examples of known software for QA purposes are listed below (from [1 ]): • • • • U ltraIQ ™ (Cablon Medical, NL) This company has developed a software application for automated evaluation and reporting of ultrasound systems dedicated to Levels and applications (http: //www.ultraiq.com); accessed 29 6.201 QA4U S ™ (Radboud University, N ijmegen, NL) a modular software package that can be used for Levels and test requirements (www qa4us eu); accessed 26 6.201 FirstCheck ™ (U ltraSound-Lab, ZMPBMT, Medical U niversity Vienna, Austria) Java-based software that is dedicated to support simple user tests/documentation of Level (http: //www.zmpbmt.meduniwien.ac at/1 /science/ultrasound-lab/projects/firstcheck/); accessed 30 201 Nottingham USQC (N ottingham University Hospitals, Medical Physics & Clinical Engineering, U K) software developed by the ultrasound group to evaluate Levels and tests One set of software is described here as an example of the newer quantitative measurements of image uniformity and as a convenience to users of this document This multi-platform software will be available shortly as a plug-in to N IH I mageJ 5) (free at http: //rsbweb nih.gov/ij/) TI FF images and stacks and uncompressed DI COM data containing rectangular and arc scan regions are processed A median image of the image stack is created with one plug-in and the data analysed with either the linear array or convex curvedlinear array plug-in The operator positions and resizes the analysis window below the main transducer ring-down and for a distance of approximately one-eighth of the total depth of the image Additionally, one can reposition the window to catch any variations of concern Output of the analysis is shown in Figure B.1   Before exporting the profile to a spreadsheet, the threshold for defect detection is considered The threshold should be at the institution’s standard value (recommended times the median absolute deviations from the data's median, MADs) The MAD is similar to the standard deviation Before the profile is exported from the plug-in, the number of transducer elements in the tested array should be set at the known value (set at 28, if unknown) This gives, as in Table B.1 , the normalized signal below MAD integrated over all scan lines in each signal valley, as well as the same integration over columns -element wide Tentative recommended action thresholds are as follows A signal valley of area (in columns one element wide)/mean > 0, is worth counting as a defect of possible concern More than two such defects are worthy of recommending _ ) Thi s i nformati on is given for the conveni ence of u sers of this d ocu ment and d oes not constitu te an endorsement by I EC of these prod ucts Copyright International Electrotechnical Commission – 30 – I EC TS 62736:201 © IEC 201 repair/replacement or further testing A finding of normalized area > 0, in a single valley is worthy of an unacceptable rating and a request for repair/replacement or further testing with strong justification of no further action These recommendations are yet to be verified on a large number of transducers and, in any case, may be subject to the individual institution’s assessment of the importance of the defect to clinical practice A classification guide is that a dip > dB (–3 dB relative to the mean) and more than two elements wide is worth counting as a defect of possible concern I f the dynamic range of the display is not known and cannot be estimated reasonably, "A signal valley of area (in columns element wide)/mean > 0, 4" can be used as a guide This is the area of the dip in pixel values integrated over the number of columns of one transducer element width, taken from the –3 MAD level This criterion assumes correct entry of the number of transducer elements I f this n umber is un known, a reasonable guess for high-end systems in 201 is (1 28 + 92)/2 = 60 Taking the area of this dip in pixel values is like taking a certain number of decibels assuming a standard dynamic range setting and a purely logarithmic characteristic curve This latter assumption is most accurate in the middle of the image brightness range IEC Profi l e col um ns below M ADs (medi an absolu te d evi ati ons) are shown i n blu e Figu re B.1 – On the left the profile of median pixel value is plotted for each image column in the analysis box shown in the median image on the right for the transducer in Figure , but without the nylon filament obstructing some central elements After being made aware of these defects by this procedure and having quantitative measures to test, the user can follow minor acceptable defects until replacement, if further degradation occurs Alternatively, on a servicer contract allowing a certain transducer replacement rate, the most defective transducers currently in the user’s possession can be replaced as the nocost opportunity arises Below, see a step-by-step example of performing this analysis Copyright International Electrotechnical Commission I EC TS 62736:201 © IEC 201 – 31 – Table B.1 – Output of analysis The bottom two rows provi de a l isti ng and measu red characteristi cs of the sig nal d i ps M in an d Si g nal at hal f max are i n pi xel valu es Area is integrated pixel val u e i n the d i ps an d mean in Area/mean is the mean pi xel val u e in the anal ysed area of the i mage Di p depth in d B is maximu m d epth calcu lated assuming a pu rel y l ogari thmic com pression and th e entered d yn ami c range of 70 i n thi s case Di p area (d B elements) is j ust th e in teg rated Di p area i n d B Anoth er col umn shou l d be ad d ed , giving th e distance of each d ip from the end of the transd u cer that h as the bump or ri d ge provi d ed on i t to d ori entati on i n cli nical use MAD is d efin ed as the med i an of the absol u te d evi ati ons from the d ata's med ian These sheets can be worksheets in a workbook for the given transdu cer, scanner or facili ty A master spread sheet sh oul d keep the results for a given transd ucer i n a colu mn for d ocu m entation and anal ysis of chang e B.2 Example of QC control chart: A control chart can plot results of a series of measurements over time Confidence or control limits or standard deviations of the data are plotted as horizontal lines showing the likelihood that a point is deviating from the mean due to other than the fluctuations in the data, assuming a random, Gaussian measurement error I n the example of Figure B 2, the sudden increase in the area of the dip, if reproducible, indicates transducer, cable or electronic degradation that warrants repair, replacement or further diagnosis The dip is shown as stable for several months within standard deviations from the mean before jumping to a more serious defect This apparent change is more cause for concern than a modest stable defect The dip area is labelled in depth of the dip in decibels integrated over the number of involved transducer elements [SOURCE: spreadsheet from [36], plotted with modifications] Copyright International Electrotechnical Commission – 32 – I EC TS 62736:201 © IEC 201 Control ch art: TD C9-4 S/N 31 9234 40 Di p area (d B el ements) 35 30 25 20 15 10 9/6/1 0/7/1 1 /5/1 Test d ate 2/5/1 /9/1 IEC Figure B.2 – Control chart for a dip in the middle of the profile for one transducer (TD) mode C9-4 and the specified serial number (S/N) Copyright International Electrotechnical Commission I EC TS 62736:201 © IEC 201 – 33 – Annex C (informative) Display test patterns Two types of display test patterns, Figure C.1 and Figure C 3, are chosen for this document because of their simplicity for visual and, if desired, photometric analysis Both of the test patterns in Figure C.1 are recommended These are simple dark field and light field patterns One is shown with and one without a grid to aid reporting of sections of reduced or accentuated brightness The grid pattern is recommended to simplify data entry as in Figure C (left) I t is important that each pattern fills the screen Evaluate each for visibly acceptable uniformity when viewed from each side, above and below, and from straight ahead Unlike most patterns, it is not essential for those in Figure C.1 and Figure C to have a one-on-one relationship between the image pixels and the display pixels Patterns in DICOM and 6-bit TI FF formats should be displayed with a window and level set to cover the range from to 095 (WW = 096, WL = 048) For 8-bit patterns, the displayed range should be from to 255 (WW = 256, WL = 28)       IEC Li ned (left) or unli ned (ri ght) patterns may be u sed Figure C.1 – AAPM TG1 8-UN1 (left) and TG1 8-UN80 (right) patterns for luminance uniformity, colour uniformity, and angular response evaluations [35] For the required assessments of the contrast transfer characteristics associated with the luminance response of a device, the low contrast test pattern [35] represented in Figure C is employed The pattern includes adjacent regions varying in luminance from levels to 248 with an 8-bit display and 28 to 968 with bits Each region differs in pixel value by the same amount from the adjacent ones Each patch contains four small corner patches at ± [ ± 64 with bits] pixel value difference from the background, identical to those in the TG1 8QC test pattern I n addition, at the centre of each patch is a half-moon target with the two sides of the target at ± [ ± 32] pixel value difference from the background For Figure C (right), state the lowest contrast pattern in each row at which the central split circle can be distinguished A similar pattern OIQ (I EC 62563-1 [34]) is perhaps even better for this purpose for LED displays   Copyright International Electrotechnical Commission – 34 – I EC TS 62736:201 © IEC 201 IEC Figure C.2 – Example data entry form for visual display evaluation: left for Figure C.1 ; right for Figure C.3 IEC Figure C.3 – TG1 8-CT low-contrast test pattern for the evaluation of the luminance response of display systems [35] Copyright International Electrotechnical Commission I EC TS 62736:201 © IEC 201 – 35 – Annex D (informative) Electronic test methods and test methods provided by the manufacturers; relation to clinical significance Two methods are discussed in 4, including electronic test methods from an independent supplier and test methods provided by the manufacturers Writers are unaware of transducer tests provided by the system manufacturers with results provided to the users, but this testing is done internally in some systems A device for complete electrical tests of the transducer cable and the elements (FirstCall aPerio™ ) ) was sold commercially but has since been restricted A system for imaging the surface vibrations of a transducer array can fully check the transmission capabilities of even a 2D imaging array without requiring electrical connections and pin-to-element knowledge ) The test methods in this document for transducer element and channel malperformance are quite sensitive, but their connection to image quality at the depths of interest in the image plane are not fully understood Professional judgement is used to determine actual thresholds for various actions to improve the system performance after defects and, possibly, evolution thereof have been documented by these tests When questionable defects are detected, further testing with existing performance evaluation standards and Technical Specification is recommended (I EC 61 391 -1 , I EC 61 391 -2, and I EC TS 62791 [1 5] or I EC TS 62558 [24]) More specific image-quality performance-evaluation methods can help elucidate the importance of various transducer defects in relation to the various costs of transducer replacement or repair A full-blown clinical trial in various clinical applications with defective and properly functioning transducers is not worth the cost A useful test method, however, could involve use of the simulated ideal observer and simulated image artifacts on databases of borderline pathologies with adjustable lesion contrast and simulated element/channel dropout _ ) Fi rstCall aPerio™ is the trad emark of a prod u ct su ppli ed by U ni syn M ed ical Technol ogi es, Gol d en, CO, U SA Thi s i nformati on is given for the conveni ence of u sers of this d ocu ment and d oes not constitu te an end orsement by I EC of this prod u ct ) Au reon ™ is an exampl e of a su itabl e prod u ct avail able com merci ally (su ppli ed by Acertara Acou stic Laboratori es, Lon gmont, CO, U SA, http: //www acertaral abs com /prod ucts/for-h ospi tals/au reon/) This i nformati on is g iven for the conveni ence of u sers of this d ocu men t and does not constitu te an end orsement by I EC of this prod u ct Copyright International Electrotechnical Commission – 36 – I EC TS 62736:201 © IEC 201 Bibliography [1 ] EFSU MB, “Guideline for technical quality assurance (TQA) of ultrasound devices (BMode) – Version 0” (Kollmann C , Dekorte C , Dudley N J , Gritzmann N , Martin K , Evans D H ) Ultraschall in der Medizin 33(6), p 544-549 (201 2) [2] Padilla F , Carson P.L., van der Spek S , LeCarpentier G., Goodsitt M M Toward a truly meaningful method of U S-system quality control I n Proc RSNA 96th Scientific Assembly and Annual Meeting, Radiology, 257, abstract only, Chicago, Nov 28 – Dec 3, 201 [3] King D M , Hangiandreou N J , Tradup D.J and Stekel S.F Evaluation of a low-cost liquid ultrasound test object for detection of transducer artifacts Physics in Medicine and Biology 55(23), N557-N570 (201 0) [4] Hangiandreou N J , Stekel S.F , Tradup D.J Four Year Experience with an U ltrasound Quality Control Program, in Proc Amer I nst Ultras Med Ann Conv , J Ultrasound Med , Suppl., 28 S1 , S1 48-9, New York (2009) [5] Hangiandreou N J , Stekel S F , Tradup D.J , Gorny K.R , King D M , Four-year experience with a clinical ultrasound quality control program Ultrasound Med Biol 37(8), p 350-1 357 (201 ) [6] King D M , Hangiandreou N J , Tradup D.J , Stekel S F Assessment of three methods for detection of ultrasound artifacts Medical Physics 38(1 ), p 621 6-6221 (201 ) [7] Sipilä O , Mannila V , Vartiainen E , Quality assurance in diagnostic ultrasound Eur J Radiol 80(2), p 51 9-525 (201 ) [8] Balbis S , Meloni T , Tofani S , Zenone F , N ucera D , Guiot C , Criteria and scheduling of quality control of B-mode and doppler ultrasonography equipment J Clin Ultrasound 40(3), p 67-1 73 (201 2) [9] Sipilä O , Blomqvist P , J auhiainen M , Kilpeläinen T , Malaska P , Mannila V , Vinnurva-J ussila T , Virsula S , "Reproducibility of phantom-based quality assurance parameters in real-time ultrasound imaging, " Acta Radiologica 52(6), p 665-669 (201 ) [1 0] Märtensson M , Olsson M., Segall B , Fraser A.G , Winter R , Brodin L Ö , H igh incidence of defective ultrasound transducers in use in routine clinical practice European Journal of Echocardiography 0(3), p 389-394 (2009) [1 ] Pfandzelter R , Sander G , Balhar T , Langer M , Technical quality assurance in diagnostic ultrasound in outpatient care in Germany, Technische Qualitätssicherung der U ltraschalldiagnostik in der ambulanten Versorgung Ultraschall in der Medizin 33(6), p 574-580 (201 2) [1 2] Shaw A and Hekkenberg R , Standards to support performance evaluation for diagnostic ultrasound imaging equipment National Physical Laboratory N PL Report AC Teddington, U K, 2007 68 p [1 3] AAPM Real-time B-mode ultrasound quality control test procedures, Report of AAPM U ltrasound Task Group N o.1 , (M M Goodsitt, P L Carson, D L H ykes, J M Kofler), Med Phys 25 (8) 08-1 998 [1 4] I PEM Routine quality assurance of ultrasound imaging systems, (R Price), Institute for Physics and Engineering in Medicine, Report 71 , 2002 (originally published by I nstitute for Physical Sciences in Medicine, 995) [1 5] I EC TS 62791 , Ultrasonics – Pulse-echo scanners – Low-echo sphere phantoms and method for performance testing of gray-scale medical ultrasound scanners applicable to a broad range of transducer types Copyright International Electrotechnical Commission I EC TS 62736:201 © IEC 201 – 37 – [1 6] Shi H , Al-Sadah J , Mackie T , Zagzebski J , Signal to noise ratio estimates of ultrasound depth of penetration Med Ph ys 30(6), p 367-1 367 (2003) (Abstract) [1 7] Madsen E.L., Frank G.R., McCormick M M , Deaner M E , Stiles T A Anechoic sphere phantoms for estimating 3-D resolution of very-high-frequency ultrasound scanners IEEE Tra n s Ultra son , Fe rroe lect , Freq Con trol 57, p 2284-2292 (201 0) [1 8] Leys, C et al Detecting outliers: Do not use standard deviation around the mean, use absolute deviation around the median J Exp Soc Psych ol 49, p 764–766 (201 3) [1 9] AI UM Sta n da rd Me th ods for Mea surin g Pe rforma n ce of Pulse -Ech o Ultra soun d American Institute of U ltrasound in Medicine Laurel, MD, U SA Ima gin g Equip me n t (1 990) [20] Goodsitt M , Carson P.L , Witt S , H ykes D I , and Kofler J M Real Time B-mode U ltrasound Quality Control Test Procedures Me d Ph ys 25, p 385-1 406 (1 998) [21 ] Üstüner K and Holley G U ltrasound I maging System Performance Assessment In Proce edin gs of th e 2003 Me e tin g of th e A me rica n A ssocia tion , Pittsburgh, PA, U SA, July 2003 http: //www.aapm org/meetings/03AM/pdf/9905-9858.pdf Medicin e [22] [23] Text of Ph ysicists available in at: U ltrasound Accreditation Program Requirements, Amer Col Radiol , http: //www.acraccreditation.org/~/media/Documents/U ltrasound/Requirements.pdf?la= en, Rev 5/2/1 I EC TS 61 390:1 996, Ultra son ics – Re a l-time pulse -e ch o syste ms – Te st p roce dure s to de termin e pe rforma n ce sp ecifica tion s [24] I EC TS 62558, 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) [25] Gorny K.R , Tradup D J , Hangiandreou N J I mplementation and validation of three automated methods for measuring ultrasound maximum depth of penetration: application to ultrasound quality control Me d Ph ys 32(8), p 261 5-2628 (2005) [26] Tradup D , Johnson L , Stekel S , H angiandreou N Initial experience with an automated system for measuring ultrasound image quality J Ultra soun d Med 26: S230, (2007) March, (Abstract) [27] Gibson N , Dudle N , Griffith, K A computerised quality control testing system for Bmode ultrasound Ultra soun d Me d Biol 27, p 697-1 71 (2001 ) [28] Tissue Substitute s, Ph a n toms a n d Comp uta tion a l Mode llin g in Me dica l Ultra soun d I nternational Commission on Radiation U nits and Measurements ICRU Report 61 Bethesda, MD, U SA (1 998) [29] Madsen E , Zagzebski J , Banjavic R and J utila R Tissue-mimicking materials for ultrasound phantoms Me d Ph ys 5, p 391 -394 (1 978) [30] Madsen E U ltrasonically soft-tissue-mimicking materials In Th e Me dica l Ph ysics of CT , Fullerton G and Zagzebski J , editors, AAPM Monograph 6, American Association of Physicists in Medicine, New York, N Y, USA p 531 -550 (1 980) a n d Ultra soun d: Tissue Ima gin g a n d Ch a cte riza tion [31 ] Madsen E L , Frank G R , Dong F Liquid or solid ultrasonically tissue-mimicking materials with very low scatter Ultra soun d Me d Biol 24(4), p 535-542 (1 998) [32] Wilson T , Zagzebski J , Li Y.D A test phantom for estimating changes in the effective frequency of an ultrasonic scanner J Ultra soun d Me d 21 (9), p 937-945 (2002) [33] DI COM Standards Committee WG, U ltrasound, Digital Imaging and Communications in Medicine (DI COM) Supplement 43: Storage of 3D Ultrasound Images, Apr 2009, Copyright International Electrotechnical Commission – 38 – I EC TS 62736:201 © IEC 201 (DICOM), Digital I maging and Communications ftp: //medical nema org/medical/dicom/final/sup43_ft pdf in Medicine [34] I EC 62563-1 , Medical electrical equipment – Medical image display systems – Part : Evaluation methods [35] AAPM Task Group I maging I nformatics Subcommittee, E Samei, Chair, Assessment of Display Performance for Medical I maging Systems, AAPM On-Line Report N o 03, College Park, MD , 2005 http: //www.aapm.org/pubs/reports/OR_03 pdf [36] Tague, N R Seven Basic Quality Tools I n The Quality Toolbox American Society for Quality, Milwaukee, Wisconsin, U SA (2005) p (I ncludes example control chart in Excel.) [37] AI UM Quality Assurance Manual for Gray Scale Ultrasound Scanners AI UM Technical Standards Committee, American Institute of Ultrasound in Medicine, Laurel, MD, USA p 58-68 (201 4) _ Copyright International Electrotechnical Commission Copyright International Electrotechnical Commission INTERNATIONAL ELECTROTECHNICAL COMMISSI ON 3, rue de Varembé PO Box 31 CH-1 21 Geneva 20 Switzerland Tel: + 41 22 91 02 1 Fax: + 41 22 91 03 00 info@iec.ch www.iec.ch Copyright International Electrotechnical Commission