BS EN 61262-5-1995 Characteristics of electro-optical X-ray image intensifiers for medical electrical equipment - Determination of the detective quantum efficiency《医疗电气设备用光电X射线图象增强.pdf

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1、BRITISH STANDARD BS EN 61262-5:1995 IEC1262-5: 1994 Characteristics of electro-optical X-ray image intensifiers for medical electrical equipment Part 5: Determination of the detective quantum efficiency The European Standard EN61262-5:1994 has the status of a BritishStandardBSEN61262-5:1995 This Bri

2、tishStandard, having been prepared under the directionof the Health and Environment Sector Board(H/-),was published undertheauthority of the StandardsBoardand comes into effect on 15 April1995 BSI01-2000 The following BSI references relate to the work on this standard: Committee reference HCC/72 Dra

3、ft for comment 94/501345DC ISBN 0 580 24035 5 Committees responsible for this BritishStandard The preparation of this BritishStandard was entrusted to Technical Committee HCC/72, Image intensifiers, upon which the following bodies were represented: Association of X-ray Equipment Manufacturers (BEAMA

4、 Ltd.) British Institute of Radiology College of Radiographers Institute of Physical Sciences in Medicine (Ipsm) Amendments issued since publication Amd. No. Date CommentsBSEN61262-5:1995 BSI 01-2000 i Contents Page Committees responsible Inside front cover National foreword ii Foreword 2 Text of EN

5、61262-5 3 List of references Inside back coverBSEN61262-5:1995 ii BSI 01-2000 National foreword This BritishStandard has been prepared by Technical Committee HCC/72 and is the English language version of EN61262-5:1994 Medical electrical equipment Characteristics of electro-optical X-ray image inten

6、sifiers Part5 Determination of the detective quantum efficiency, published by the European Committee for Electrotechnical Standardization (CENELEC). It is identical with IEC1262-5:1994 published by the International Electrotechnical Commission (IEC). Additional information. The following print types

7、 are used in this standard. Requirements, with which compliance can be tested, and definitions: in roman type. Explanations, advice, general statements, exceptions and references: in smaller type. Test procedures: in italic type Terms defined in clause3 of this standard and in Annex A: in SMALL CAPI

8、TALS. For the purposes of this BritishStandard, any references to IEC page numbers in the text should be ignored. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a Bri

9、tish Standard does not of itself confer immunity from legal obligations. Cross-references Publication referred to Corresponding BritishStandard HD501 S1 (IEC788:1984) BS6641:1985 Glossary of medical radiology terms Summary of pages This document comprises a front cover, an inside front cover, pagesi

10、 andii, theEN title page, pages2 to12, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN6126

11、2-5 September1994 ICS 11.040.50 Descriptors: Medical electrical equipment,image intensifier, X-ray, detection English version Medical electrical equipment Characteristics of electro-optical X-ray image intensifiers Part5: Determination of the detective quantum efficiency (IEC1262-5:1994) Appareils l

12、ectromdicaux Caractristiques des intensificateurs lectro-optiques dimage radiologique Partie5: Dtermination de lefficacit quantique de dtection (CEI1262-5:1994) Medizinische elektrische Gerte Merkmale von elektronenoptischen Rntgenbildverstrkern Teil5: Bestimmung der detektiven Quanten-Ausbeute (IEC

13、1262-5:1994) This European Standard was approved by CENELEC on1994-07-05. 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 bibl

14、iographical 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 responsibili

15、ty 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, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy,Luxembourg, Netherla

16、nds, Norway, Portugal, Spain, Sweden, Switzerland and UnitedKingdom. CENELEC European Committee for Electrotechnical Standardization Comit Europen de Normalisation Electrotechnique Europisches Komitee fr Elektrotechnische Normung Central Secretariat: rue de Stassart 35, B-1050 Brussels 1994 Copyrigh

17、t reserved to CENELEC members Ref. No. EN61262-5:1994 EEN61262-5:1994 BSI 01-2000 2 Foreword The text of document62B(CO)116, as prepared by Sub-Committee62B: Diagnostic imaging equipment, of IEC Technical Committee62: Electrical equipment in medical practice, was submitted to the IEC-CENELEC paralle

18、l vote in January1994. The reference document was approved by CENELEC as EN61262-5 on5 July1994. The following dates were fixed: For products which have complied with the relevant national standard before1995-07-01, as shown by the manufacturer or by a certification body, this previous standard may

19、continue to apply for production until2000-07-01. Annexes designated “normative” are part of the body of the standard. Annexes designated “informative” are given only for information. In this standard, Annex A, Annex B, Annex C and Annex D, are informative and Annex ZA is normative. Contents Page Fo

20、reword 2 Introduction 3 1 Scope 3 2 Normative reference 3 3 Terminology 3 3.1 Definitions 3 3.2 Degree of requirements and reading instructions 4 4 Requirements 4 4.1 Test set-up 4 4.2 X-RAY IMAGE INTENSIFIER Operating conditions 5 4.3 Input radiation 5 4.4 TEST DEVICE 5 4.5 Measurement equipment 5

21、5 Determination of the DETECTIVE QUANTUM EFFICIENCY 6 5.1 Preparation 6 5.2 Measurement 7 5.3 Corrections 7 5.4 Determination 7 6 Presentation of the DETECTIVE QUANTUM EFFICIENCY 7 7 Statement of compliance 8 Annex A (informative) Terminology Index of terms 9 Annex B (informative) Representative tes

22、t set-up 10 Annex C (informative) Representative scintillation pulse-height spectra 10 Annex D (informative) Bibliography 11 Annex ZA (normative) Other international publications quoted in this standard with thereferences of the relevant European publications 12 Figure 1 Geometrical relationship of

23、RADIATION SOURCE and INPUT APERTURE 8 Figure C.1 Reference detector 10 Figure C.2 XRII 11 latest date of publication of an identical national standard (dop)1995-07-01 latest date of withdrawal of conflicting national standards (dow)1995-07-01EN61262-5:1994 BSI 01-2000 3 Introduction DETECTIVE QUANTU

24、M EFFICIENCY (DQE) is a measure of the imaging quality of a system based on a comparison of the signal-to-noise ratio (SNR) at its output to the SNR at its input. For linear imaging systems, SNR and DQE can be conveniently analysed in terms of sinusoidally varying signals. This standard gives detail

25、ed specifications for the determination of the DQE of ELECTRO-OPTICAL X-RAY IMAGE INTENSIFIERS near zero frequency for both spatial and temporal frequencies. The method employed is scintillation spectrum analysis (SSA). The source of input radiation is the radionuclide 241 Am, which is preferred ove

26、r an X-RAY SOURCE because of the radionuclides freedom from drift and periodic fluctuations in its output while providing gamma-rays in a radiologically interesting energy range. The signal at the output phosphor of the ELECTRO-OPTICAL X-RAY IMAGE INTENSIFIER is integrated over an area that is large

27、 compared to the image of the source. Additionally, the SSA method requires integration of essentially all of the optical photon energy at the ELECTRO-OPTICAL X-RAY IMAGE INTENSIFIER output attributable to the absorption of a single gamma-ray photon. These characteristics result in a measurement nea

28、r zero for both spatial and temporal frequencies. This standard specifies the measurement of DQE only near the CENTRE OF THE ENTRANCE FIELD. Also, the SSA method is not recommended for an ELECTRO-OPTICAL X-RAY IMAGE INTENSIFIER with output phosphor radiance decay that is considerably slower than tha

29、t for a P-20 phosphor. Generally, upon absorption of a single gamma-ray photon, the resulting light pulse intensity at1ms after the onset of the pulse should be less than10% of the peak intensity. This assumes that the time interval between pulse onset and peak intensity is much shorter than1ms. Sin

30、ce the SSA method entails integrating the radiance due to individual gamma-ray photons, phosphors having appreciably slower decay would necessitate the use of very low gamma-ray photon count rates which can become comparable to background count rates. It is recognized that other methods of DQE measu

31、rement are available, e.g.,pulse-burst analysis, r.m.s. noise analysis, and estimation of quantum absorption from physical characteristics of the ELECTRO-OPTICAL X-RAY IMAGE INTENSIFIER (seeAnnex D Bibliography). Methods that provide measurements of DQE that agree within measurement accuracy with me

32、asurements obtained by the method of this standard are equally acceptable. 1 Scope This International Standard applies to ELECTRO-OPTICAL X-RAY IMAGE INTENSIFIER for medical use, as components of diagnostic X-RAY EQUIPMENT. This International Standard describes a method of determining the DETECTIVE

33、QUANTUM EFFICIENCY (DQE) of X-RAY IMAGE INTENSIFIERS by analysis of the single gamma-ray photon scintillation pulse-height spectrum. The method of this standard applies only to ELECTRO-OPTICAL X-RAY IMAGE INTENSIFIERS having output radiance decay rates approximately equal to or faster than that of a

34、 P-20 phosphor. 2 Normative reference The following standard contains provisions which, through reference in this text, constitute provisions of this International Standard. At the time of publication, the edition indicated was valid. All standards are subject to revision, and parties to agreements

35、based on this International Standard are encouraged to investigate the possibility of applying the most recent edition of the standard indicated below. Members of IEC and ISO maintain registers of currently valid International Standards. IEC788:1984, Medical Radiology Terminology. 3 Terminology 3.1

36、Definitions For the purposes of this International Standard, the following definitions apply together with those given in IEC788. The definitions given below take preference over those given in IEC788 when differences occur. 3.1.1 XRII an abbreviation for ELECTRO-OPTICAL X-RAY IMAGE INTENSIFIER 3.1.

37、2 ENTRANCE PLANE the plane perpendicular to the axis of symmetry of the XRII and grazing the part of the XRII, including its housing, that protrudes most in the direction of the RADIATION SOURCE 3.1.3 ENTRANCE FIELD for an XRII, the area in the ENTRANCE PLANE that can be used for the transmission of

38、 an X-RAY PATTERN under specific conditionsEN61262-5:1994 4 BSI 01-2000 3.1.4 Not used. 3.1.5 SOURCE TO ENTRANCE PLANE DISTANCE (abbreviation SED) the distance between the FOCAL SPOT of the X-RAY TUBE and the ENTRANCE PLANE of the XRII 3.1.6 CENTRE OF THE OUTPUT IMAGE the centre of the smallest circ

39、le circumscribing the OUTPUT IMAGE 3.1.7 CENTRE OF THE ENTRANCE FIELD that point in the ENTRANCE PLANE which is imaged at the CENTRE OF THE OUTPUT IMAGE 3.1.8 CENTRAL AXIS the line perpendicular to the ENTRANCE PLANE passing through the CENTRE OF THE ENTRANCE FIELD 3.1.9 Not used. 3.1.10 EFFECTIVE A

40、PERTURE the area of the INPUT SCREEN of the XRII which is irradiated by the RADIATION SOURCE through the INPUT APERTURE NOTEDue to geometrical enlargement and the source size, the diameter of this area is always larger than the diameter of the INPUT APERTURE itself. 3.1.11 DETECTIVE QUANTUM EFFICIEN

41、CY (abbreviation DQE) the ratio of the squared signal-to-noise ratio present at the output of a RADIATION DETECTOR to the squared signal-to-noise ratio present at the input of that RADIATION DETECTOR 3.1.12 QUANTUM ABSORPTION EFFICIENCY the number of photons incident at the input of a RADIATION DETE

42、CTOR that yield a signal at the output of the RADIATION DETECTOR divided by the total number of incident photons 3.1.13 INPUT APERTURE the aperture that determines the cross-sectional area of a RADIATION BEAM 3.1.14 SINGLE GAMMA-RAY PHOTON PULSE the number of light photons emitted by the OUTPUT SCRE

43、EN of the XRII attributable to the interaction of one gamma-ray photon of specific energy in the INPUT SCREEN of the XRII 3.2 Degree of requirements and reading instructions In this International Standard the auxiliary verb: 4 Requirements The instrumentation characteristics and their settings neede

44、d for the determination of the DQE are given in this clause. A representative measurement set-up is shown in Annex B. 4.1 Test set-up Not used. “shall” implies that compliance with a requirement is mandatory for compliance with the standard; “should” implies that compliance with a requirement is str

45、ongly recommended but is not mandatory for compliance with the standard; “may” implies that compliance with a requirement is permitted to be accomplished in a particular manner, for compliance with the standard; and the following words have the meaning: “specific” when used in combination with param

46、eters or conditions: refers to a particular value or standardized arrangement, usually to those required in an IEC Standard or a legal requirement; see IEC788, rm-74-01. “specified” when used in combination with parameters or conditions: refers to a value or arrangement to be chosen for the purpose

47、under consideration and indicated usually in ACCOMPANYING DOCUMENTS; see IEC788, rm-74-02. “designed for” when used in standards to characterize equipment, devices, components or arrangements: designates an intended and usually apparent purpose or use for the product.EN61262-5:1994 BSI 01-2000 5 4.2

48、 X-RAY IMAGE INTENSIFIER Operating conditions a) The XRII shall be operated under the conditions for NORMAL USE as specified by the manufacturer. b) No ANTI-SCATTER GRID or protective cover shall be used. c) In the case of multiple-field XRIIs, the measurement shall be made for the largest specified

49、 ENTRANCE FIELD. 4.3 Input radiation a) The RADIATION SOURCE of input radiation shall be the radionuclide 241 Am, which emits gamma-ray photons having an energy of59,5keV. b) The output of the source might include quanta other than those from the decay of 241 Am, for example, L X-rays of neptunium and fluorescence X-rays from the material used in the construction of the source and its container. 1) The fluence rate of quanta with energies other than59,5keV shall be less than1% of the fluence rate of59,5keV quanta. The requir