EN 62220-1-2-2007 en Medical electrical equipment - Characteristics of digital X-ray imaging devices - Part 1-2 Determination of the detective quantum efficiency - Detectors used i.pdf

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1、BRITISH STANDARDBS EN 62220-1-2:2007Medical electrical equipment Characteristics of digital X-ray imaging devices Part 1-2: Determination of the detective quantum efficiency Detectors used in mammographyThe European Standard EN 62220-1-2:2007 has the status of a British StandardICS 11.040.50g49g50g3

2、g38g50g51g60g44g49g42g3g58g44g55g43g50g56g55g3g37g54g44g3g51g40g53g48g44g54g54g44g50g49g3g40g59g38g40g51g55g3g36g54g3g51g40g53g48g44g55g55g40g39g3g37g60g3g38g50g51g60g53g44g42g43g55g3g47g36g58BS EN 62220-1-2:2007This British Standard was published under the authority of the Standards Policy and Stra

3、tegy Committee on 30 November 2007 BSI 2007ISBN 978 0 580 55696 8National forewordThis British Standard is the UK implementation of EN 62220-1-2:2007. It is identical to IEC 62220-1-2:2007.The UK participation in its preparation was entrusted by Technical Committee CH/62, Electromedical equipment in

4、 medical practice, to Subcommittee CH/62/2, Diagnostic imaging equipment.A list of organizations represented on this committee can be obtained on request to its secretary.This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct ap

5、plication.Compliance with a British Standard cannot confer immunity from legal obligations.Amendments issued since publicationAmd. No. Date CommentsEUROPEAN STANDARD EN 62220-1-2 NORME EUROPENNE EUROPISCHE NORM September 2007 CENELEC European Committee for Electrotechnical Standardization Comit Euro

6、pen de Normalisation Electrotechnique Europisches Komitee fr Elektrotechnische Normung Central Secretariat: rue de Stassart 35, B - 1050 Brussels 2007 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members. Ref. No. EN 62220-1-2:2007 E ICS 11.040.50

7、English version Medical electrical equipment - Characteristics of digital X-ray imaging devices - Part 1-2: Determination of the detective quantum efficiency - Detectors used in mammography (IEC 62220-1-2:2007) Appareils lectromdicaux - Caractristiques des dispositifs dimagerie numrique rayonnement

8、X - Partie 1-2: Dtermination de lefficacit quantique de dtection - Dtecteurs utiliss en mammographie (CEI 62220-1-2:2007) Medizinische elektrische Gerte - Merkmale digitaler Rntgenbildgerte - Teil 1-2: Bestimmung der detektiven Quanten-Ausbeute - Bildempfnger fr Mammographieeinrichtungen (IEC 62220-

9、1-2:2007) This European Standard was approved by CENELEC on 2007-09-01. 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 biblio

10、graphical 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

11、 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, Cyprus, the Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece,

12、 Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom. Foreword The text of document 62B/649/FDIS, future edition 1 of IEC 62220-1-2, prepared by SC 62B, Diagn

13、ostic imaging equipment, of IEC TC 62, Electrical equipment in medical practice, was submitted to the IEC-CENELEC parallel vote and was approved by CENELEC as EN 62220-1-2 on 2007-09-01. The following dates were fixed: latest date by which the EN has to be implemented at national level by publicatio

14、n of an identical national standard or by endorsement (dop) 2008-06-01 latest date by which the national standards conflicting with the EN have to be withdrawn (dow) 2010-09-01 In this standard, terms printed in SMALL CAPITALS are used as defined in IEC/TR 60788, in Clause 3 of this standard or othe

15、r IEC publications referenced in the Index of defined terms. Where a defined term is used as a qualifier in another defined or undefined term it is not printed in SMALL CAPITALS, unless the concept thus qualified is defined or recognized as a “derived term without definition”. NOTE Attention is draw

16、n to the fact that, in cases where the concept addressed is not strongly confined to the definition given in one of the publications listed above, a corresponding term is printed in lower-case letters. In this standard, certain terms that are not printed in SMALL CAPITALS have particular meanings, a

17、s follows: “shall“ indicates a requirement that is mandatory for compliance; “should“ indicates a strong recommendation that is not mandatory for compliance; “may“ indicates a permitted manner of complying with a requirement or of avoiding the need to comply; “specific“ is used to indicate definitiv

18、e information stated in this standard or referenced in other standards, usually concerning particular operating conditions, test arrangements or values connected with compliance; “specified“ is used to indicate definitive information stated by the manufacturer in accompanying documents or in other d

19、ocumentation relating to the equipment under consideration, usually concerning its intended purposes, or the parameters or conditions associated with its use or with testing to determine compliance. This European Standard has been prepared under a mandate given to CENELEC by the European Commission

20、and the European Free Trade Association and covers essential requirements of EC Directive MDD (93/42/EEC). See Annex ZZ. Annexes ZA and ZZ have been added by CENELEC. _ Endorsement notice The text of the International Standard IEC 62220-1-2:2007 was approved by CENELEC as a European Standard without

21、 any modification. _ EN 62220-1-2:2007 2 CONTENTS INTRODUCTION.4 1 Scope.5 2 Normative references .5 3 Terminology and definitions6 4 Requirements .8 4.1 Operating conditions .8 4.2 X-RAY EQUIPMENT .8 4.3 RADIATION QUALITY .8 4.4 TEST DEVICE .9 4.5 Geometry 10 4.6 IRRADIATION conditions.11 5 Correct

22、ions of RAW DATA .14 6 Determination of the DETECTIVE QUANTUM EFFICIENCY.15 6.1 Definition and formula of DQE(u,v) 15 6.2 Parameters to be used for evaluation 15 6.3 Determination of different parameters from the images16 7 Format of conformance statement 20 8 Accuracy 20 Annex A (normative) Determi

23、nation of LAG EFFECTS21 Annex B (informative) Calculation of the input NOISE POWER SPECTRUM.24 Bibliography25 Terminology Index of defined terms .27 Annex ZA (normative) Normative references to international publications with theircorresponding European publications29 Annex ZZ (informative) Coverage

24、 of Essential Requirements of EC Directives .30 EN 62220-1-2:2007 3 INTRODUCTION DIGITAL X-RAY IMAGING DEVICES are increasingly used in medical diagnosis and will widely replace conventional (analogue) imaging devices such as screen-film systems or analogue X-RAY IMAGE INTENSIFIER television systems

25、 in the future. It is necessary, therefore, to define parameters that describe the specific imaging properties of these DIGITAL X-RAY IMAGING DEVICES and to standardize the measurement procedures employed. There is growing consensus in the scientific world that the DETECTIVE QUANTUM EFFICIENCY (DQE)

26、 is the most suitable parameter for describing the imaging performance of an X-ray imaging device. The DQE describes the ability of the imaging device to preserve the signal-to-NOISE ratio from the radiation field to the resulting digital image data. Since in X-ray imaging, the NOISE in the radiatio

27、n field is intimately coupled to the AIR KERMA level, DQE values can also be considered to describe the dose efficiency of a given DIGITAL X-RAY IMAGING DEVICE. NOTE In spite of the fact that the DQE is widely used to describe the performance of imaging devices, the connection between this physical

28、parameter and the decision performance of a human observer is not yet completely understood 1, 3.1)The DQE is already widely used by manufacturers to describe the performance of their DIGITAL X-RAY IMAGING DEVICES. The specification of the DQE is also required by regulatory agencies (such as the Foo

29、d and Drug Administration (FDA) for admission procedures. However, there is presently no standard governing either the measurement conditions or the measurement procedure with the consequence that values from different sources may not be comparable. This standard has therefore been developed in orde

30、r to specify the measurement procedure together with the format of the conformance statement for the DETECTIVE QUANTUM EFFICIENCY of DIGITAL X-RAY IMAGING DEVICES. In the DQE calculations proposed in this standard, it is assumed that system response is measured for objects that attenuate all energie

31、s equally (task-independent) 5. This standard will be beneficial for manufacturers, users, distributors and regulatory agencies. It is the second document out of a series of three related standards: Part 1, which is intended to be used in RADIOGRAPHY, excluding MAMMOGRAPHY and RADIOSCOPY; the presen

32、t Part 1-2, which is intended to be used for MAMMOGRAPHY; Part 1-3, which is intended to be used for dynamic imaging detectors. These standards can be regarded as the first part of the family of 62220 standards describing the relevant parameters of DIGITAL X-RAY IMAGING DEVICES. 1)Figures in square

33、brackets refer to the bibliography. EN 62220-1-2:2007 4 MEDICAL ELECTRICAL EQUIPMENT CHARACTERISTICS OF DIGITAL X-RAY IMAGING DEVICES Part 1-2: Determination of the detective quantum efficiency Detectors used in mammography 1 Scope This part of IEC 62220 specifies the method for the determination of

34、 the DETECTIVE QUANTUM EFFICIENCY (DQE) of DIGITAL X-RAY IMAGING DEVICES as a function of AIR KERMA and of SPATIAL FREQUENCY for the working conditions in the range of the medical application as specified by the MANUFACTURER. The intended users of this part of IEC 62220 are manufacturers and well eq

35、uipped test laboratories. This Part 1-2 is restricted to DIGITAL X-RAY IMAGING DEVICES that are used for mammographic imaging such as but not exclusively, CR systems, direct and indirect flat panel detector based systems, scanning systems (CCD based or photon-counting). This part of IEC 62220 is not

36、 applicable to DIGITAL X-RAY IMAGING DEVICES intended to be used in general radiography or in dental radiography; computed tomography; and devices for dynamic imaging (where series of images are acquired, as in fluoroscopic or cardiac imaging). NOTE The devices noted above are excluded because they

37、contain many parameters (for instance, beam qualities, geometry, time dependence, etc.) which differ from those important for mammography. Some of these techniques are treated in separate standards (IEC 62220-1 and IEC 62220-1-3) as has been done for other topics, for instance for speed and contrast

38、, in IEC and ISO standards. 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

39、. IEC 60336, Medical electrical equipment X-ray tube assemblies for medical diagnosis Characteristics of focal spots IEC TR 60788:2004, Medical electrical equipment Glossary of defined terms IEC 60601-2-45, Medical electrical equipment Part 2-45: Particular requirements for the safety of mammographi

40、c X-ray equipment and mammographic stereotactic devices IEC 61267:2005, Medical diagnostic X-ray equipment Radiation conditions for use in the determination of characteristics EN 62220-1-2:2007 5 IEC 62220-1:2003, Medical electrical equipment Characteristics of digital X-ray imaging devices Part 1:

41、Determination of the detective quantum efficiency ISO 12232:1998, Photography Electronic still-picture cameras Determination of ISO speed 3 Terms and definitions For the purpose of this document, the terms and definitions given in IEC 60788 which are listed in the Index of defined terms and the foll

42、owing apply. 3.1 CONVERSION FUNCTION plot of the large area output level (ORIGINAL DATA) of a DIGITAL X-RAY IMAGING DEVICE versus the number of exposure quanta per unit area (Q) in the DETECTOR SURFACE plane NOTE 1 Q is to be calculated by multiplying the measured AIR KERMA excluding back scatter by

43、 the value given in column 4 of Table 2. NOTE 2 Many calibration laboratories, such as national metrology institutes, calibrate RADIATION METERS to measure AIR KERMA. IEC 62220-1:2003, definition 3.2, modified 3.2 DETECTIVE QUANTUM EFFICIENCY DQE(u,v) ratio of two NPS functions with the numerator be

44、ing the NPS of the input signal at the DETECTOR SURFACE of a digital X-ray detector after having gone through the deterministic filter given by the system transfer function, and the denominator being the measured NPS of the output signal (ORIGINAL DATA) NOTE Instead of the two-dimensional DETECTIVE

45、QUANTUM EFFICIENCY, often a cut through the two-dimensional DETECTIVE QUANTUM EFFICIENCY along a specified line in the frequency plane is published. IEC 62220-1:2003, definition 3.3, modified 3.3 DETECTOR SURFACE accessible area which is closest to the IMAGE RECEPTOR PLANE NOTE After removal of all

46、parts (including the ANTI-SCATTER GRID and components for AUTOMATIC EXPOSURE CONTROL, if applicable) that can be safely removed from the RADIATION BEAM without damaging the digital X-ray detector. IEC 62220-1:2003, definition 3.4, modified 3.4 DIGITAL X-RAY IMAGING DEVICE device consisting of a digi

47、tal X-ray detector including the protective layers installed for use in practice, the amplifying and digitizing electronics, and a computer providing the ORIGINAL DATA (DN) of the image IEC 62220-1:2003, definition 3.5 3.5 IMAGE MATRIX arrangement of MATRIX ELEMENTS preferentially in a Cartesian coo

48、rdinate system IEC 62220-1:2003, definition 3.6, modified EN 62220-1-2:2007 6 3.6 LAG EFFECT influence from a previous image on a current one IEC 62220-1:2003, definition 3.7 3.7 LINEARIZED DATA ORIGINAL DATA to which the inverse CONVERSION FUNCTION has been applied NOTE The LINEARIZED DATA are dire

49、ctly proportional to the AIR KERMA. IEC 62220-1:2003, definition 3.8 3.8 MODULATION TRANSFER FUNCTION MTF(u,v) modulus of the generally complex optical transfer function, expressed as a function of SPATIAL FREQUENCIES u and v IEC 62220-1:2003, definition 3.9 3.9 NOISE fluctuations from the expected value of a stochastic process IEC 62220-1:2003, definition 3.10 3.10 NOISE POWER SPECTRUM NPS W(u,v) modulus of the Fourier transform of the NOISE auto-co