ASTM E2737-10(2018) Standard Practice for Digital Detector Array Performance Evaluation and Long-Term Stability.pdf

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1、Designation: E2737 10 (Reapproved 2018)Standard Practice forDigital Detector Array Performance Evaluation and Long-Term Stability1This standard is issued under the fixed designation E2737; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revi

2、sion, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice describes the evaluation of DDA systemsfor industrial radiology. It is intended to ens

3、ure that theevaluation of image quality, as far as this is influenced by theDDA system, meets the needs of users, and their customers,and enables process control and long term stability of the DDAsystem.1.2 This practice specifies the fundamental parameters ofDigital Detector Array (DDA) systems to

4、be measured todetermine baseline performance, and to track the long termstability of the DDA system.1.3 The DDA system performance tests specified in thispractice shall be completed upon acceptance of the systemfrom the manufacturer and at intervals specified in this practiceto monitor long term sta

5、bility of the system. The intent of thesetests is to monitor the system performance for degradation andto identify when an action needs to be taken when the systemdegrades by a certain level.1.4 The use of the gages provided in this standard ismandatory for each test. In the event these tests or gag

6、es arenot sufficient, the user, in coordination with the cognizantengineering organization (CEO) may develop additional ormodified tests, test objects, gages, or image quality indicatorsto evaluate the DDA system. Acceptance levels for theseALTERNATE tests shall be determined by agreement betweenthe

7、 user, CEO and manufacturer.1.5 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety, health, and environmental practices and deter-mine the applicability of regulat

8、ory limitations prior to use.1.6 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Orga

9、nization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2E1025 Practice for Design, Manufacture, and MaterialGrouping Classification of Hole-Type Image Quality In-dicators (IQI) Used for RadiologyE1316 Terminology for Nondestructive ExaminationsE1742/E1742M Prac

10、tice for Radiographic ExaminationE2002 Practice for Determining Total Image Unsharpnessand Basic Spatial Resolution in Radiography and Radios-copyE2445/E2445M Practice for Performance Evaluation andLong-Term Stability of Computed Radiography SystemsE2597/E2597M Practice for Manufacturing Characteriz

11、ationof Digital Detector ArraysE2698 Practice for Radiological Examination Using DigitalDetector ArraysE2736 Guide for Digital Detector Array Radiology3. Terminology3.1 DefinitionsThe definition of terms relating to gammaand X-radiology, which appear in Terminology E1316, PracticeE2597/E2597M, Guide

12、 E2736, and Practice E2698 shall applyto the terms used in this practice.3.2 Definitions of Terms Specific to This Standard:3.2.1 digital detector array (DDA) systeman electronicdevice that converts ionizing or penetrating radiation into adiscrete array of analog signals which are subsequently digi-

13、tized and transferred to a computer for display as a digitalimage corresponding to the radiologic energy pattern impartedupon the input region of the device. The conversion of theionizing or penetrating radiation into an electronic signal maytranspire by first converting the ionizing or penetrating

14、radia-tion into visible light through the use of a scintillating material.These devices can range in speed from many seconds per1This practice is under the jurisdiction of ASTM Committee E07 on Nonde-structive Testing and is the direct responsibility of Subcommittee E07.01 onRadiology (X and Gamma)

15、Method.Current edition approved Feb. 1, 2018. Published February 2018. Originallyapproved in 2010. Last previous edition approved in 2010 as E2737 10. DOI:10.1520/E2737-10R18.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For

16、 Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationa

17、lly recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.1image to many images per second, up to and in excess of

18、real-time radioscopy rates (usually 30 frames per seconds).3.2.2 active DDA areathe active pixelized region of theDDA, which is recommended by the manufacturer as usable.3.2.3 signal-to-noise ratio (SNR)quotient of mean valueof the intensity (signal) and standard deviation of the intensity(noise). T

19、he SNR depends on the radiation dose and the DDAsystem properties.3.2.4 contrast-to-noise ratio (CNR)quotient of the differ-ence of the signal levels between two material thicknesses, andstandard deviation of the intensity (noise) of the base material.The CNR depends on the radiation dose and the DD

20、A systemproperties.3.2.5 contrast sensitivityrecognized contrast percentageof the material to examine. It depends on 1/CNR.3.2.6 spatial resolution (SR)the spatial resolution indi-cates the smallest geometrical detail, which can be resolvedusing the DDA with given geometrical magnification. It is th

21、ehalf of the value of the detector unsharpness divided by themagnification factor of the geometrical setup and is similar tothe effective pixel size.3.2.7 material thickness range (MTR)the wall thicknessrange within one image of a DDA, whereby the thinner wallthickness does not saturate the DDA and

22、at the thicker wallthickness, the signal is significantly higher than the noise.3.2.8 frame ratenumber of frames acquired per second.3.2.9 lagresidual signal in the DDA that occurs shortlyafter detector read-out and erasure.3.2.10 burn-inchange in gain of the scintillator that per-sists well beyond

23、the exposure.3.2.11 bad pixela pixel identified with a performanceoutside of the specification range for a pixel of a DDA asdefined in Practice E2597/E2597M.3.2.12 five-groove wedgea continuous wedge with fivelong grooves on one side (see Fig. 1).3.2.13 phantoma part or item being used to quantify D

24、DAcharacterization metrics.3.2.14 duplex plate phantomtwo plates of the same mate-rial; Plate 2 has same size in x- and half the size in v- directionof Plate 1; the thickness of Plate 1 matches the minimumthickness of the material for inspection; the thickness of Plate1 plus Plate 2 matches the maxi

25、mum thickness of the materialfor inspection (see Fig. 2).3.2.15 DDA offset imageimage of the DDA in the absenceof x-rays providing the background signal of all pixels.3.2.16 DDA gain imageimage obtained with no structuredobject in the x-ray beam to calibrate pixel response in a DDA.3.2.17 calibratio

26、ncorrection applied for the offset signaland the non-uniformity of response of any or all of the X-raybeam, scintillator, and the read out structure.3.2.18 gray valuethe numeric value of a pixel in the DDAimage. This is typically interchangeable with the term pixelvalue, detector response, Analog-to

27、-Digital unit and detectorsignal.3.2.19 saturation gray valuethe maximum possible usablegray value of the DDA after offset correction.NOTE 1Saturation may occur because of a saturation of the pixelitself, the amplifier, or digitizer, where the DDA encounters saturationgray values as a function of in

28、creasing exposure levels.3.2.20 userthe user and operating organization of theDDA system.3.2.21 customerthe company, government agency, orother authority responsible for the design, or end user, of thesystem or component for which radiologic examination isrequired, also known as the CEO. In some ind

29、ustries, thecustomer is frequently referred to as the “Prime”.3.2.22 manufacturerDDA system manufacturer, supplierfor the user of the DDA system.4. Significance and Use4.1 This practice is intended to be used by the NDT usingorganization to measure the baseline performance of the DDAand to monitor i

30、ts performance throughout its service as anNDT imaging system.4.2 It is to be understood that the DDA has already beenselected and purchased by the user from a manufacturer basedon the inspection needs at hand. This practice is not intended tobe used as an “acceptance test” of the DDA, but rather to

31、establish a performance baseline that will enable periodicperformance tracking while in-service.4.3 Although many of the properties listed in this standardhave similar metrics to those found in Practice E2597/E2597M, data collection methods are not identical, and com-parisons among values acquired w

32、ith each standard should notbe made.4.4 This practice defines the tests to be performed andrequired intervals. Also defined are the methods of tabulatingresults that DDA users will complete following initial baselin-ing of the DDA system. These tests will also be performedperiodically at the stated

33、required intervals to evaluate theDDA system to determine if the system remains withinacceptable operational limits as established in this practice ordefined between user and customer (CEO).4.5 There are several factors that affect the quality of a DDAimage including the spatial resolution, geometri

34、calunsharpness, scatter, signal to noise ratio, contrast sensitivity(contrast/noise ratio), image lag, and burn in. There are severaladditional factors and settings (for example, integration time,detector parameters or imaging software), which affect theseresults. Additionally, calibration technique

35、s may also have animpact on the quality of the image. This practice delineatestests for each of the properties listed herein and establishesstandard techniques for assuring repeatability throughout thelifecycle testing of the DDA.5. General Testing Procedures5.1 The tests performed herein can be com

36、pleted either bythe use of the five-groove wedge phantom (see Fig. 1) or withseparate IQIs on the Duplex Plate Phantom (see Fig. 2).E2737 10 (2018)25.2 DDA Calibration MethodPrior to testing, the DDAshall be calibrated for offset and, or gain to generate correctedimages per manufacturers recommendat

37、ion. It is importantthat the calibration procedure be completed as would be donein production during routine calibration procedures, and thatthese same procedures be used throughout the periodic testingof the DDA after it is in-service.5.3 Bad Pixel Standardization for DDAsImages collectedfor testin

38、g shall be corrected for bad pixels as would be donein production during routine bad pixel correction proceduresper manufacturers recommendation wherever required. Astandardized nomenclature is presented in Practice E2597/E2597M. The identification and correction of bad pixels in adelivered DDA rema

39、in in the purview of agreement betweenthe user and the system manufacturer. The various tests shall becompleted under similar conditions as in production. Someparameters to control are listed below. If several differentenergies are used in production, the complete settings with thehighest energy lev

40、el shall be used for these tests.5.3.1 X-ray tube voltage kV5.3.2 tube current mA5.3.3 focus detector distance (FDD) mm5.3.4 object detector distance (ODD) mm5.3.5 total exposure time per image ms5.3.6 detector corrections (calibration and bad pixel substi-tution)5.3.7 detector settings5.3.8 image a

41、cquisition software and image processingFIG. 1 5-Groove-Wedge (steel) see AppendixE2737 10 (2018)36. Application of Baseline Tests and Test Methods6.1 DDA System Baseline Performance Tests6.1.1 The user shall accept the DDA system based onmanufacturers results of Practice E2597/E2597M on thespecific

42、 detector as provided in a data sheet for that serializedDDA or other agreed to acceptance test between the user andmanufacturer (not covered in this practice). The user baselinesthe DDA using the tests defined in Table 1. Additional tests areto be defined in agreement between the CEO and the usingo

43、rganization in terms of the specific tests to perform, how thedata is presented, and the frequency of testing. This approachdoes the following:6.1.1.1 Provides a quantitative baseline of performance,6.1.1.2 provides results in a defined form that can bereviewed by the CEO and6.1.1.3 offers a means t

44、o perform process checking ofperformance on a continuing basis.FIG. 2 Duplex Plate Phantom with IQIs positioned; one ASTM E1025 or E1742/E1742M Penetrameter on each plate and one ASTM E2002Duplex Wire IQI on the thinner plate. The boxes ROI 1 to ROI 4 are for evaluation of signal level and SNR.E2737

45、 10 (2018)46.1.2 Acceptance values, and tolerances thereof obtainedfrom these tests shall also be in agreement between the CEOand the using organization.6.1.3 Acceptance levels for individual bad pixels, badclusters, relevant bad clusters, and bad lines, and their statis-tical distribution within th

46、e DDA, as well as proximity to saidanomalies is to be determined by agreement between the userand the CEO. The user and or CEO may refer to the Guide forDDAs (E2736), Practice E2597/E2597M, as well as consultwith the manufacturer on how the prevalence of these anoma-lous pixels might impact a specif

47、ic application. This practicedoes not set limits, but does offer a means for tracking suchanomalous pixels in the table templates provided herein.6.1.4 Given that the other elements of the DDA system arewithin their tolerances including the x-ray source/generator, theimaging system, and the inspecti

48、on itself (for example errorswith gain/offset mapping are controlled, as is any severe x-rayscatter in the inspection), and the test produces a result belowthe “agreed to” requirements, the detector is not to be placed inservice unless it is repaired, replaced, or some other change isinstituted that

49、 will assure the quality of the inspection as statedin the agreement between contracting parties.6.1.5 The results of the initial test of the new system shall bedocumented, as delineated in Table 2 and Table 3 and taken asreference values “Result (new)” for further use.6.1.6 Maximum deviations from Result (new) as tolerancesand limits defined between contracting parties shall also bedocumented in Table 2 and Table 3 as reference values “Limit”for further use.6.1.7 If a replacement DDA is placed into service, thereferen