1、DEUTSCHE NORM Februarv 2000 Non-destructive testing Radioscopic testing EN 13068-2 Part 2: Check of long-termstability of imaging devices English version of DIN EN 13068-2 ICs 19.100 Zerstrungsfreie Prfung - Radioskopische Prfung - Teil 2: Prfung der Langzeitstabilitt von bildgebenden Systemen Europ
2、ean Standard EN 13068-2 : 1999 has the status of a DIN Standard. National foreword This standard has been prepared by CEN/TC 138. The responsible German body involved in its preparation was the Normenausschuss Materialprfung (Materials Testing Standards Committee), Technical Committee Durchstrahlung
3、sprfung und Strahlen- schutz. EN comprises 7 pages. No pari of this standard may be reproduced without the prior permission of Ref. No. DIN EN 13068-2 : 2000-0 Y Deutsches Institut fr Normung e. V., Berlin. Beuth Verlag GmbH, 10772 Berlin, Germany, s the exclusive right of sale for German Standards
4、(DIN-Normen). English price group O7 Sales No. 1107 07.00 EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 13068-2 December 1999 ICs 19.1 O0 English version Non-destructive testing Part 2: Check of long-term stability of imaging devices Radioscopic testing Essais non destructifs - Contrle par ra
5、dioscopie - Partie 2: Contrle de la stabilit long terme des systmes dimagerie bildgebenden Systemen Zerstrungsfreie Prfung - Radioskopische Prfung - Teil 2: Prfung der Langzeitstabilitt von This European Standard was approved by CEN on 1999-1 0-29 CEN members are bound to comply with the CENKENELEC
6、Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national stand- ards may be obtained on application to the Central Secretariat or to any CEN
7、 member. The European Standards exist in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the official versions. CEN mem
8、bers are the national standards bodies of Austria, Belgium, the Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, the Netherlands, Norway, Portugal, Spain, Sweden, Switzerland, and the United Kingdom CEN European Committee for Standardization Comit Europ
9、en de Normalisation Europisches Komitee fr Normung Central Secretariat: rue de Stassart 36, B-1050 Brussels O 1999. CEN - All rights of exploitation in any form and by any means reserved worldwide for CEN national members. Ref. No. EN 13068-2 : 1999 E Page 2 EN 13068-2 : 1999 Contents Foreword . 2 I
10、ntroduction 3 1 Scope . 3 2 Normative references 3 3 Comparison with natural defects . 3 4 Image quality by image quality indicators (IQIs) . 3 5 Identification of equipment faults 7 6 Documentation . 7 Foreword This European Standard has been prepared by Technical Committee CENTTC 138 “Non-destruct
11、ive testing“, the secretariat of which is held by AFNOR. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by June 2000, and conflicting national standards shall be withdrawn at the latest by June 2000
12、. According to the CENKENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Po
13、rtugal, Spain, Sweden, Switzerland and the United Kingdom. EN 13068 EN 1 3068-1 : 1999, Non-destructive testing - Radioscopic testing - Part 1: Quantitative measurement of imaging properiies. EN 13068-2:1999, Non-destructive testing - Radioscopic testing - Part 2: Check of long term staiiiiiy of ima
14、ging de vices. prEN 13068-3, Non-destructive testing - Radioscopic testing - Part 3: General princies of radioscopic testing of metaiiic materiais by X- and gamma rays. comprises a series of European Standards of radioscopic systems which is made up the following: Page 3 EN 13068-2 : 1999 Introducti
15、on This part of the European Standard gives an outline for the quality control of the imaging devices during operation. Reference is made to part one which deals with the quantitative measurements. A further part 3 and others will be related to special applications, e. g. weld inspection, casting in
16、spection, etc. Before operation of a new radioscopic system, a quality control procedure should be specified by the producer and the user of the system which ensures the stable and reliable performance of the radioscopic system. This procedure should include the parts of this standard, speciy the re
17、gion of interest (ROI ) on the display unit, placement of test IQls and other relevant parameters for good reproducibility of the tests. Additionally, the frequency of tests and acceptance levels for system degradation should be specified according to the requirements of NDT specifications and usage
18、 of the system. 1 Scope This part of the standard gives guidance on the on site check of equipment for radioscopy where the image is presented on a display unit including image processing. The radiation sources used can be X-rays or gamma rays. This standard establishes rules for testing a radioscop
19、ic system to assure a constant level of inspection quality. The tests should be easily performable by the operators of the system. They are based on an input signal from defined image quality indicators. The measurement of the systems response should be performed with the same equipment which is in
20、use in this particular installation. This standard is applicable to installations with an image processing computer as well as to simple display units. 2 Normative references This European Standard incorporates, by dated or undated reference, provisions from other publications. These normative refer
21、ences are cited at the appropriate places in the text and the publications are listed hereafter. For dated references, subsequent amendments to or revisions of any of these publications apply to this European standard only when incorporated in it by amendment or revision. For undated references the
22、latest edition of the publication referred to applies. EN 13068-1 :1999, Non-destructive testing - Radioscopic examination - Part I: Quantitative measurement of imaging properties. EN 462-1, Non-destructive testing - Image qual of radiographs - Part 1: Image quality indicators (wire lype) - Determin
23、ation of image qualily value. EN 462-2, Non-destructive testing - Image qualiw of radiographs - Part 2: image qualip indicators (stephole Wpe) - Determination of image qual& value. EN 462-5, Non-destructive testing - Image quak& of radiographs - Part 5: Image qual indicators (duplex wire lype), dete
24、rmination of image unsharpness value. 3 Comparison with natural defects Tests with natural defects are not sufficient as the only quality control for the comparison of the actual system performance with the first day appearance. The performance of the radioscopic system should be tested to its abili
25、ty to image and recognize the typical and the critical defects of a certain component. In addition to standardized IQIs, samples with smallest or most difficult to detect natural defects can be used for a routine quality control of the overall system performance. 4 Image quality control by image qua
26、lity indicators (IQls) 4.1 General The quality of a radioscopic image is essentially determined by sharpness, contrast and linearity. These parameters which have been described in EN 13068-1 :1999 depend on the Set-up of source, imaging system and specimen. For the purpose of quality control they sh
27、all be supervised by checking the overall performance of the radioscopic Set-up on a routine basis during operation and with the same operational Set-up used in usual operation. This can be achieved by means of image quality indicators. For all specimens the IQI has to be placed at the source side o
28、f the specimen if this is possible. Page 4 EN 13068-2 : 1999 If there are additional parts of this standard on specific inspection subjects (e. g. prEN 13068-3) they shall be supplied during quality control. 4.2 Experimental procedure 4.2.1 General Set-up To achieve reproducible results which allow
29、the control of the long-term stability of a system, it is necessary to define a standardized Set-up for the measurements. An example is shown in figure 1. Its details shall be documented for later reproduction. The document shall contain the data of the X-ray source, such as type of tube, voltage an
30、d current settings, filtering of X-rays and additional details, which may influence the image quality. Collimators when used shall be described. Test indicators shall be placed at the source side of the component under inspection. They produce a defined radiation relief as an input signal. The perfo
31、rmance tests shall be carried out with the same equipment and parameter settings as used under operational conditions. During measurements the radioscopic system shall be operated in accordance with the instruction manual and manufacturer instructions. 4.2.2 Display unit Display units used in radios
32、copy shall be operated with selectors for brightness and contrast, properly adjusted following the instructions of the manufacturer. For systems with a frame buffer a digitized test chart should be loaded for the adjustment of the display unit. Test charts for this purpose can be taken from standard
33、 video technique. The settings shall not be changed until the next test. 4.3 Measurement procedures 4.3.1 Check of unsharpness The sharpness of the system can be degradated mainly by the lenses, the signal detector and ageing processes of the converter screens. For tests during practical work the to
34、tal system unsharpness can be registered only. The total system unsharpness shall be checked with an image quality indicator (IQI) of the duplex wire type according to EN 462-5 as the test object. It shall be placed on the source side of the object. The object shall be plane and represent the typica
35、l test specimen in terms of thickness and material. The unsharpness is position dependent. A region of interest (ROI) on the field of view shall be defined, where the image quality shall fulfill the sharpness criteria given by the particular inspection problem. The unsharpness shall meet these condi
36、tions in the whole ROI . The unsharpness shall be checked by placing the IQI horizontally and vertically in the direction of the detector read out lines. For systems with an image processing computer, the profile across the IQI shall be evaluated. The profiles are similar to figure 2. The number of
37、the duplex wire for which the modulation depth is closest to 20 % and the numerical value of the modulation depth itself shall be evaluated and documented for comparison with later measurements. Also the number of the rst unresolved wire pair according to the EN 462-5 shall be written to the documen
38、t file. The total unsharpness required depends on the radiation energy to be used with the equipment. The arrangement parameters shall be documented for later reproduction. 4.3.2 Check of contrast sensitivity For the measurement of contrast sensitivity and wall thickness range a step wedge in accord
39、ance with EN 13068- 1:1999, made of the same material as the sample under investigation can be used. In addition, to comply with the requirements for standard radiography, the corresponding IQI according to EN 462-1 or EN 462-2 has to be placed accordingly. If integrated to the system, noise reducti
40、on by recursive filtering or image integration can be used. The type of algorithm and relevant parameters shall be documented for proper reproduction. The detectability of the corresponding radiographic IQI can be used as a sufficient image quality indication with respect to the signal noise ratio.
41、This should be measured with an image processing computer if there is one integrated to the inspection system. Page 5 EN 13068-2 : 1999 Key 1 radiation source 6 image processing a distance source - 1st collimator 2 radiation filter 7 display unit b distance source - 2nd collimator 3 image quality in
42、dicator 8 collimator c distance source - conversion device 4 conversion device 9 object d thickness of filter 5 output signal er.s thickness of 1st resp. 2nd collimator f distance source - object Figure 1 - Typical Set-up Page 6 EN 13068-2 : 1999 a Output signal H-M. 100 Modulation depth (O/)= H Fig
43、ure 2 - Intensity profile across double wire Page 7 EN 13068-2 : 1999 4.3.3 Check of homogeneity During the life-time of an imaging system there can be some degradation of homogeneity due to masking or bum-out of the luminescence screens or of the optical or camera system. The local inhomogeneities
44、can be outside the areas to be evaluated and of no relevance. However, disturbances in homogeneity within the regions of interest may heavily deteriorate the image and therefore the image evaluation. The control of inhomogeneity in an image is carried out by placing the IQls used for the test of con
45、trast sensitivity and spatial resolution at various areas of the regions of interest. The locations and type of IQI shall be documented. The time dependence of the homogeneity within the image can be measured with an image processing system by comparison of the actual image to an image stored at the
46、 time of installation. This can be done by image subtraction or intensity profile comparison. During the life-time of an imaging system additional dark or light spots may occur which shall be registrated on the display unit or measured and stored as x, y pixel address by the image processing system.
47、 In those cases, where dimensional measurements are carried out, the linearity of the imaging system has to be verified by appropriate calibration. 4.3.4 Systems for inspection of moving parts Radioscopic equipment can be used for inspection of moving parts. The motion generates an additional contri
48、bution to the unsharpness which depends on the speed. For better reproducibility and to eliminate this influence , the system performance should be tested with unmoved parts. Image sensors can have remanences on their target. When inspecting moving parts, these remanences become visible and influenc
49、e the image quality. This effect shall be considered. 5 Identification of equipment faults If the check of long-term stability reveals that the spatial and/or contrast resolution is no longer satisfying the initially specified requirements, the system components have to be analysed. First, it should be ensured that the geometric Set-up is correct and identical with the documentation of earlier tests. If there are lenses in the system, it is recommended to test them first for good focussing. The electronic components should be tested following the instructi
