1、Designation: E2736 10E2736 17Standard Guide forDigital Detector Array RadiologyRadiography1This standard is issued under the fixed designation E2736; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A numb
2、er in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This standard is a user guide, which is intended to serve as a tutorial for selection and use of various digital detector arraysystems nomi
3、nally composed of the detector array and an imaging system to perform digital radiography. This guide also servesas an in-detail reference for the following standards: Practices E2597, E2698, and E2737.1.2 This standard does not purport to address all of the safety concerns, if any, associated with
4、its use. It is the responsibilityof the user of this standard to establish appropriate safety safety, health, and healthenvironmental practices and determine theapplicability of regulatory limitations prior to use.1.3 This international standard was developed in accordance with internationally recog
5、nized principles on standardizationestablished in the Decision on Principles for the Development of International Standards, Guides and Recommendations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2E94 Guide for Radiograp
6、hic Examination Using Industrial Radiographic FilmE155 Reference Radiographs for Inspection of Aluminum and Magnesium CastingsE192 Reference Radiographs of Investment Steel Castings for Aerospace ApplicationsE747 Practice for Design, Manufacture and Material Grouping Classification of Wire Image Qua
7、lity Indicators (IQI) Used forRadiologyE1000 Guide for RadioscopyE1025 Practice for Design, Manufacture, and Material Grouping Classification of Hole-Type Image Quality Indicators (IQI)Used for RadiologyE1316 Terminology for Nondestructive ExaminationsE1320 Reference Radiographs for Titanium Casting
8、sE1742 Practice for Radiographic ExaminationE1815 Test Method for Classification of Film Systems for Industrial RadiographyE1817 Practice for Controlling Quality of Radiological Examination by Using Representative Quality Indicators (RQIs)E2002 Practice for Determining Total Image Unsharpness and Ba
9、sic Spatial Resolution in Radiography and RadioscopyE2422 Digital Reference Images for Inspection of Aluminum CastingsE2445 Practice for Performance Evaluation and Long-Term Stability of Computed Radiography SystemsE2446 Practice for Manufacturing Characterization of Computed Radiography SystemsE259
10、7 Practice for Manufacturing Characterization of Digital Detector ArraysE2660 Digital Reference Images for Investment Steel Castings for Aerospace ApplicationsE2669 Digital Reference Images for Titanium CastingsE2698 Practice for Radiological Examination Using Digital Detector ArraysE2737 Practice f
11、or Digital Detector Array Performance Evaluation and Long-Term Stability2.2 ISO Document:3ISO 17636-2 Non-Destructive Testing of WeldsRadiographic Testing - Part 2: X- and Gamma-Ray Techniques with DigitalDetector1 This guide is under the jurisdiction of ASTM Committee E07 on Nondestructive Testing
12、and is the direct responsibility of Subcommittee E07.01 on Radiology (X andGamma) Method.Current edition approved April 15, 2010Dec. 1, 2017. Published July 2010February 2018. Originally approved in 2010. Last previous edition approved in 2010 asE2736 10. DOI: 10.1520/E2736-17.2 For referencedASTM s
13、tandards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.3 Available from International Organization for Standardization (ISO), ISO Central
14、Secretariat, BIBC II, Chemin de Blandonnet 8, CP 401, 1214 Vernier, Geneva,Switzerland, http:/www.iso.org.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be tech
15、nically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO
16、Box C700, West Conshohocken, PA 19428-2959. United States13. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 digital detector array (DDA) systeman electronic device that converts ionizing or penetrating radiation into a discretearray of analog signals which are subsequently digit
17、ized and transferred to a computer for display as a digital image correspondingto the radiation energy pattern imparted upon the input region of the device. The conversion of the ionizing or penetrating radiationinto an electronic signal may transpire by first converting the ionizing or penetrating
18、radiation into visible light through the useof a scintillating material. These devices can range in speed from many minutes per image to many images per second, up to andin excess of real-time radioscopy rates (usually 30 frames per seconds).3.1.2 signal-to-noise ratio (SNR)quotient of mean value of
19、 the intensity (signal) and standard deviation of the intensity(noise). The SNR depends on the radiation dose and the DDA system properties.3.1.3 normalized signal-to-noise ratio (SNRn)SNR normalized for basic spatial resolution (see Practice E2445).3.1.4 basic spatial resolution (SRb)basic spatial
20、resolution indicates the smallest geometrical detail, which can be resolvedusing the DDA. It is similar to the effective pixel size.3.1.5 effciencydSNRn (see 3.1.6 of Practice E2597) divided by the square root of the dose (in mGy) and is used to measurethe response of the detector at different beam
21、energies and qualities.3.1.1 achievable contrast sensitivity (CSa)optimumbest contrast sensitivity (see Terminology E1316 for a definition ofcontrast sensitivity) obtainable using a standard phantom with an X-ray technique that has little contribution from scatter.3.1.7 specific material thickness r
22、ange (SMTR)material thickness range within which a given image quality is achieved.3.1.2 contrast-to-noise ratio (CNR)bad pixelquotient of the difference of the mean signal levels between two image areasand the standard deviation of the signal levels. The CNR depends on the radiation dose and the DD
23、Asystem properties.a bad pixelis a pixel identified with a performance outside of the specification for a pixel of a DDA as defined in Practice E2597.3.1.9 lagresidual signal in the DDA that occurs shortly after the exposure is completed.3.1.3 burn-inchange in gain of the scintillator or photoconduc
24、tor that persists well beyond the exposure.3.1.11 internal scatter radiation (ISR)scattered radiation within the detector (from scintillator, photodiodes, electronics,shielding, or other detector hardware).3.1.4 bad pixeleffciencyaSNRn bad pixel is a pixel identified with a performance outside of th
25、e(see 3.1.6 of PracticeE2597specification for a pixel of a DDAas defined in Practice) divided by the square root of the dose (in mGy) E2597.and is usedto measure the response of the detector at different beam energies and qualities.3.1.5 grooved wedgea wedge with one groove, that is 5 % of the base
26、material thickness and that is used for achievablecontrast sensitivity measurement in Practice E2597.3.1.6 internal scatter radiation (ISR)scattered radiation within the detector (from scintillator, photodiodes, electronics,shielding, or other detector hardware).3.1.7 lagresidual signal in the DDA t
27、hat occurs shortly after the exposure is completed.3.1.8 phantoma part or item being used to quantify DDA characterization metrics.3.1.9 SNRNSNR, normalized by the basic spatial resolution SRb as measured directly in the digital image and/or calculatedfrom measured SNRmeasured by:SNRN 5SNRmeasured 3
28、S88.6 mSRbD (1)3.1.10 specific material thickness range (SMTR)material thickness range within which a given image quality is achieved.4. Significance and Use4.1 This standard provides a guide for the other DDA standards (see Practices E2597, E2698, and E2737). It is not intendedfor use with computed
29、 radiography apparatus. Figure 1 describes how this standard is interrelated with the aforementionedstandards.4.2 This guide is intended to assist the user to understand the definitions and corresponding performance parameters used inrelated standards as stated in 4.1 in order to make an informed de
30、cision on how a given DDAcan be used in the target application.4.3 This guide is also intended to assist cognizant engineering officers, prime manufacturers, and the general service andmanufacturing customer base that may rely on DDAs to provide advanced radiological results so that these parties ma
31、y set theirown acceptance criteria for use of these DDAs by suppliers and shops to verify that their parts and structures are of sound integrityto enter into service.4.4 The manufacturer characterization standard for DDA(see Practice E2597) serves as a starting point for the end user to selecta DDA
32、for the specific application at hand. DDA manufacturers and system integrators will provide DDA performance data usingE2736 172standardized geometry, X-ray beam spectra, and phantoms as prescribed in Practice E2597. The end user will look at theseperformance results and compare DDA metrics from vari
33、ous manufacturers and will decide on a DDA that can meet thespecification required for inspection by the end user. See Sections 5 and 8 for a discussion on the characterization tests andguidelines for selection of DDAs for specific applications.4.5 Practice E2698 is designed to assist the end user t
34、o set up the DDA with minimum requirements for radiologicalexaminations. This standard will also help the user to get the required SNR, to set up the required magnification, and providesguidance for viewing and storage of radiographs. Discussion is also added to help the user with marking and identi
35、fication of partsduring radiological examinations.4.6 Practice E2737 is designed to help the end user with a set of tests so that the stability of the performance of the DDA canbe confirmed. Additional guidance is provided in this document to support this standard.4.7 Figure 1 provides a summary of
36、the interconnectivity of these four DDA standards.4.8 DDAs may be used with significant success under a wide energy range, i.e. from 10 kV to 20 MeV if configuredappropriately. However in this document some phantoms such as the duplex wire gauge (Practice E2002) may not give an accuraterepresentatio
37、n of the basic spatial resolution at energies above 600 kV.FIG. 1 Flow Diagram Representing the Connection Between the Four DDA StandardsE2736 1735. DDA Technology Description5.1 General Discussion:5.1.1 DDAs are seeing increased use in industries to enhance productivity and quality of nondestructiv
38、e testing. DDAs are beingused for in-service nondestructive testing, as a diagnostic tool in the manufacturing process, and for inline testing on productionlines. DDAs are also being used as hand held, or scanned devices for pipeline inspections, in industrial computed tomographysystems, and as part
39、 of large robotic scanning systems for imaging of large or complex structures. Because of the digital natureof the data, a variety of new applications and techniques have emerged recently, enabling quantitative inspection and automaticdefect recognition.5.1.2 DDAs can be used to detect various forms
40、 of electromagnetic radiation, or particles, including gamma rays, X-rays,neutrons, or other forms of penetrating radiation. This standard focuses on X-rays and gamma rays.5.1.3 AreaDDAs are area imaging devices and as such can capture much more information in a single exposure than a LinearDetector
41、Array (LDA), or a linear-DDA. For the balance of this standard, the term LDAshall be considered a linear detector array,while a DDA shall be considered an area device. When capturing an area of interest, a DDA may capture a full area in a singleexposure, while an LDA captures only a single line in a
42、n exposure. To capture an area of interest, the LDA needs a series ofadjacent line scans and thereby a series of exposures.5.1.4 Despite the advantages in 5.1.3, there is a tradeoff in that the DDA devices are prone to higher levels of Compton scatter.For example, the use of a fan beam over the use
43、of a cone beam will inherently produce less Compton scatter from the object, orfrom the side walls of an X-ray cabinet. Secondly, the LDA can more effectively collimate this scatter using a narrow slit. Thatsaid, the DDA can be configured with a set of adjustable jaws both about the detector and/or
44、the source to reduce the scatter field,but the benefit of its projected coverage is diminished.5.1.5 When considering the SNR as a tradeoff, the LDAhas an advantage compared to DDAs. LDAs have significantly thickerscintillators, and thereby require a lower radiation dose to produce a successful imag
45、e per line compared to a DDA. For a givenoverall exposure time, because of the thicker scintillator in an LDA, there could be situations where it produces a higher SNRcompared to the thinner scintillator in a DDA. Also, for a given SNR, there could be situations where more overall exposure timeis ne
46、eded for a DDA.5.1.6 DDAs also enable a facile correction for differences in pixel value response (gain) across the DDA, X-ray beam shading,offset levels of the device, and bad pixels. These corrections result in a highly uniform and linear response to the X-ray beam andprovides the capability to pr
47、ovide very high and uniform signal to noise response with respect to the X-ray beam incident on theDDA. These corrections are not necessarily simple to perform with film or computed radiography systems where the SNR mightbe limited by a structure noise inherent in the imaging medium, or the shading
48、of the X-ray beam.5.1.7 Unlike film or computed radiography (CR) systems, the ability to flex the sensor, for example around a pipe has not yetbeen realized, and is certainly one of the advantages of these other imaging media over DDA devices.5.1.8 Another difference between film/CR is that these de
49、vices/media will enable very long exposure times. For example unlikea DDA there is not any restriction on frame rate. That said, a DDA can overcome this shortfall by averaging frames to achievethe desired image quality. All X-ray imaging devices will suffer from poor SNR if the dynamic nature of the inspection is too fastto capture enough photons as an object transits the beam.5.2 DDA architecture:5.2.1 A common aspect of the different forms of this technology is the use of discrete sensors (position-sensitive) where, thedata from each discrete locati
