1、December 2012 Translation by DIN-Sprachendienst.English price group 13No part of this translation may be reproduced without prior permission ofDIN Deutsches Institut fr Normung e. V., Berlin. Beuth Verlag GmbH, 10772 Berlin, Germany,has the exclusive right of sale for German Standards (DIN-Normen).I
2、CS 19.100!$“1929992www.din.deDDIN EN 16016-3Non destructive testing Radiation methods Computed tomography Part 3: Operation and interpretation;English version EN 16016-3:2011,English translation of DIN EN 16016-3:2012-12Zerstrungsfreie Prfung Durchstrahlungsverfahren Computertomografie Teil 3: Durch
3、fhrung und Auswertung;Englische Fassung EN 16016-3:2011,Englische bersetzung von DIN EN 16016-3:2012-12Essais non destructifs Mthodes par rayonnements Tomographie numrise Partie 3: Fonctionnement et interprtation;Version anglaise EN 16016-3:2011,Traduction anglaise de DIN EN 16016-3:2012-12Supersede
4、sDIN EN 16016-3:2012-01www.beuth.deDocument comprises pagesIn case of doubt, the German-language original shall be considered authoritative.2912.12 DIN EN 16016-3:2012-12 2 A comma is used as the decimal marker. National foreword This standard has been prepared by Technical Committee CEN/TC 138 “Non
5、-destructive testing” (Secretatariat: AFNOR, France). The responsible German body involved in its preparation was the Normenausschuss Materialprfung (Materials Testing Standards Committee), Working Committee NA 062-08-22 AA Durchstrahlungsprfung und Strahlenschutz. Amendments This standard differs f
6、rom DIN EN 16016-3:2012-01 as follows: a) in Subclause A.2 “Principle of measurement”, the definitions of NAand NChave been corrected. Previous editions DIN EN 16016-3: 2012-01 EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 16016-3 August 2011 ICS 19.100 English Version Non destructive testing
7、 - Radiation methods - Computed tomography - Part 3: Operation and interpretation Essais non destructifs - Mthodes par rayonnements - Tomographie numrise - Partie 3: Fonctionnement et interprtation Zerstrungsfreie Prfung - Durchstrahlungsverfahren - Computertomografie - Teil 3: Durchfhrung und Auswe
8、rtung This European Standard was approved by CEN on 29 July 2011. CEN 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 bibliographical
9、references concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN member. This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of
10、a CEN member into its own language and notified to the CEN-CENELEC Management Centre has the same status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary
11、, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG Management Centre:
12、Avenue Marnix 17, B-1000 Brussels 2011 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 16016-3:2011: EEN 16016-3:2011 (E) 2 Contents Page Foreword 3Introduction .41 Scope 52 Normative references 53 Terms and definitions .54 Operati
13、onal procedure 54.1 General 54.2 CT system set-up .54.2.1 General 54.2.2 Geometry 54.2.3 X-ray source .64.2.4 Detector 64.3 Reconstruction parameters 74.4 Visualisation .74.5 Analysis and interpretation of CT images .74.5.1 General 74.5.2 Feature testing/defect testing .74.5.3 Dimensional testing .8
14、5 Requirements for acceptable results 105.1 Image quality parameters 105.1.1 Contrast . 105.1.2 Noise 125.1.3 Signal to noise ratio . 125.1.4 Contrast to noise ratio . 125.1.5 Spatial resolution 135.2 Suitability of testing 155.3 CT examination interpretation and acceptance criteria 155.4 Records an
15、d reports . 155.5 Artefacts 165.5.1 General . 165.5.2 Beam hardening artefacts 165.5.3 Edge artefacts . 175.5.4 Scattered radiation . 185.5.5 Instabilities 185.5.6 Ring artefacts 185.5.7 Centre of rotation error artefacts 195.5.8 Motion artefacts 205.5.9 Artefacts due to an insufficient number of pr
16、ojections 215.5.10 Cone beam artefacts 21Annex A (informative) Spatial resolution measurement using line pair gauges . 23A.1 Line pair gauges . 23A.2 Principle of measurement 24Bibliography . 27DIN EN 16016-3:2012-12 EN 16016-3:2011 (E) 3 Foreword This document (EN 16016-3:2011) has been prepared by
17、 Technical Committee CEN/TC 138 “Non-destructive 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 February 2012, and conflicting national standa
18、rds shall be withdrawn at the latest by February 2012. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN and/or CENELEC shall not be held responsible for identifying any or all such patent rights. EN 16016 consists of the follow
19、ing parts: Non destructive testing Radiation methods Computed tomography Part 1: Terminology; Non destructive testing Radiation methods Computed tomography Part 2: Principle, equipment and samples; Non destructive testing Radiation methods Computed tomography Part 3: Operation and interpretation; No
20、n destructive testing Radiation methods Computed tomography Part 4: Qualification. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Repu
21、blic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom. DIN EN 16016-3:2012-12 EN 16016-3:2011 (E) 4 Introd
22、uction This document gives guidelines for the general principles of X-ray computed tomography (CT) applicable to industrial imaging (in the context of this standard, industrial means non-medical applications); it also gives a consistent set of CT performance parameter definitions, including how thes
23、e performance parameters relate to CT system specifications. This document deals with computed axial tomography and excludes other types of tomography such as translational tomography and tomosynthesis. DIN EN 16016-3:2012-12 EN 16016-3:2011 (E) 5 1 Scope This European Standard specifies an outline
24、of the operation of a CT system, and the interpretation of the results in order to provide the user with technical information to select suitable parameters. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only t
25、he edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. EN 16016-1:2011, Non destructive testing Radiation method Computed tomography Part 1: Terminology EN 16016-2:2011, Non destructive testing Radiation method Computed tom
26、ography Part 2: Principle, equipment and samples 3 Terms and definitions For the purposes of this document, the terms and definitions given in EN 16016-1:2011 apply. 4 Operational procedure 4.1 General For target-oriented CT inspection procedures, the test and measurement tasks are defined in advanc
27、e with regard to the size and type of features/defects to be verified; for example, through the specification of appropriate acceptance levels and geometry deviations. In the following, the process steps of a CT application are described and information on its implementation provided. 4.2 CT system
28、set-up 4.2.1 General The CT system set-up is oriented towards the requirements for the given task. The required spatial resolution (taking into account the tube focal spot size), contrast resolution, voxel size and the CT image quality can be derived from these requirements. The quality of the CT im
29、age is determined by different parameters, which under certain circumstances counteract each other. In the following, system parameters are described and information is provided on setting up a CT system for inspection. Due to the interactions of the different system parameters, it may be necessary
30、to run through the set-up steps several times in order to acquire optimal data. The optimal energy is that which gives the best signal-to-noise ratio and not necessarily that which gives the clearest radiograph (the dependency of the detector efficiency on the energy is to be taken into account). Ho
31、wever, in order to differentiate between materials of different chemical composition it may be necessary to adjust the accelerating voltage to maximise the difference in their linear attenuation coefficients. 4.2.2 Geometry The source-detector and source-object distances and thus also the beam angle
32、 used should be specified. In order to achieve high resolutions, the projection can be magnified onto the detector. The magnification is equal to the ratio of the source-detector distance to the source-object distance. Increasing source-detector DIN EN 16016-3:2012-12 EN 16016-3:2011 (E) 6 distance
33、leads to a reduced intensity at the detector and thus to a reduced signal to noise ratio. Accordingly, this also applies when using detectors with improved detector resolution, which can result in a reduction of the signal-to-noise ratio due to the reduced intensity per pixel. In general, for this r
34、eason, minimisation of the source-object distance is to be preferred. In order to obtain high beam intensity at the detector, the source-detector distance should be selected so that it is as small as possible taking into account the required resolution so that the beam cone still fully illuminates t
35、he detector. In the case of 3D-CT, the (in general vertical) total cone beam angle measured parallel to the rotation axis should typically be less than 15, but this is specimen dependant, in order to minimise reconstruction-determined (Feldkamp) distortions of the 3D model. In addition, these restri
36、ctions do not apply for the perpendicular (in general horizontal) beam angle. For a higher geometric magnification, the object must be positioned as near as possible to the source, taking into consideration the limit on sharpness imposed by focal spot size. The rotation of the object must take place
37、 at at least 180 plus beam angle of the X-ray beam, whereby an improved data quality is the result of an increasing number of angular increments. For this reason, the object is typically turned through 360 . Ideally, the number of angular increments should be at least sizematrix2 where the matrix si
38、ze is the number of voxels across the sample diameter or the largest dimension. For more information, refer to 5.5. In order to obtain as complete information as possible on the specimen, the requirement in general for a CT is that the object (or the interesting section of the object) is completely
39、mapped in each projection on the detector. For large components that exceed the beam cone, a so-called measurement range extension is used. This measurement range extension is accomplished by laterally displacing either the object or the detector, recording the projection data in sequential measurem
40、ents, and finally concatenating (joining) them. Under certain circumstances, it is also possible to only scan a part of the object (region-of-interest CT), which may lead to a restricted data quality in the form of so-called truncations. A possible deviation of the recording geometry (offset between
41、 the projected axis of rotation and the centre line of the image) must be corrected for in order to obtain a reconstruction which is as precise as possible. This can be achieved by careful realignment of the system or be corrected using software. 4.2.3 X-ray source At the X-ray source, the maximum b
42、eam energy and tube current are to be set such that sufficient penetration of the test object and tube power with a sufficiently small focal spot are ensured. The required voltage is determined by the maximum path length, in the material to be X-rayed in accordance with EN 16016-2:2011, 8.2. For the
43、 best measurement results, an attenuation ratio of approx. 1:10 should be used. That is the grey level through the sample should be about 10% of the white level (both measured with respect to the dark level). The optimal range can be achieved through the use of prefilters. It should be noted that ev
44、ery prefilter reduces the intensity. Prefilters have the additional advantage of reducing beam hardening, though further improvements can be made with software correction. 4.2.4 Detector The following detector settings need to be set appropriately for the sample being scanned: Exposure time (Frame r
45、ate); Number of integrations per projection; Digitisation gain and offset; Binning. If necessary, corrections for offset, gain and bad pixels (which may depend on X-ray settings) should be applied. The individual CT projection is determined by the detector properties: its geometric resolution, its s
46、ensitivity, dynamics and noise. The gain and exposure time can be adjusted together with the radiation intensity of the source so that the maximum digitised intensity does not exceed 90 % of the saturation level. DIN EN 16016-3:2012-12 EN 16016-3:2011 (E) 7 To reduce scattered radiation, a thin filt
47、er, grid or lamellae can be used directly in front of the detector (post-filtering). The ideal acquisition time is dependent on the required quality of the CT image and it is often limited by the time available for inspection. 4.3 Reconstruction parameters The volumetric region to be reconstructed,
48、the size of the CT image (in terms of voxels) as well as its dynamic range (which should take into account the detector dynamic range) shall be specified. In order to achieve sufficient CT image quality, settings for the reconstruction algorithm or corrections should be optimised. The volumetric region is defined b
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