1、Designation: E746 07 (Reapproved 2014)E746 17Standard Practice forDetermining Relative Image Quality Response of IndustrialRadiographic Imaging Systems1This standard is issued under the fixed designation E746; the number immediately following the designation indicates the year oforiginal adoption or
2、, in the case of revision, 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 standard provides a practice whereby industrial radiographic imaging syste
3、ms may be comparatively assessed usingthe concept of relative image quality response (RIQR). The RIQR method presented within this practice is based upon the use ofequivalent penetrameter sensitivity (EPS) described within Practice E1025 and subsection 5.25.3 of this practice. Figure 1illustrates a
4、relative image quality indicator (RIQI) that has four different steel plaque thicknesses (.015, .010, .008, and .005(0.015,0.010, 0.008, and 0.005 in.) sequentially positioned (from top to bottom) on an absorber plate of a 34-in. thick steel plate.specifiedmaterial and thickness. The four plaques co
5、ntain a total of 14 different arrays of penetrameter-type hole sizes designed to rendervaried conditions of threshold visibility ranging from 1.92 % EPS (at the top) to .94 % EPS (at the bottom) when exposed tonominal 200 keV X-ray the appropriate radiation. Each “EPS” array consists of 30 identical
6、 holes; thus, providing the user witha quantity of threshold sensitivity levels suitable for relative image qualitative response comparisons. There are two standardmaterials (steel and plastic) specified herein for the RIQI and absorber. For special applications the user may design a non-standardRIQ
7、I-absorber configuration; however the RIQI configuration shall be controlled by a drawing similar to Fig. 1. Use of anon-standard RIQI-absorber configuration shall be described in the users written technique and approved by the CEO.1.2 This practice is not intended to qualify the performance of a sp
8、ecific radiographic technique nor for assurance that aradiographic technique will detect specific discontinuities in a specimen undergoing radiographic examination.1.3 This practice is not intended to qualify the performance of a specific radiographic technique nor for assurance that aradiographic t
9、echnique will detect specific discontinuities in a specimen undergoing radiographic examination. This practicebeused to classify or derive performance classification categories for radiographic imaging systems. For example, performanceclassifications of radiographic film systems may be found within
10、Test Method E1815is not intended to be used to classify or deriveperformance classification categories for, and manufacturer characterization of computed radiography (CR) systems may be foundin Practice E2446radiographic imaging systems. For example, performance classifications of radiographic film
11、systems may befound within. However, the RIQI and absorber described in this practice are used by Practice E2446 Test Method for manufacturercharacterization of computed radiography (CR) systems and by Practice E1815E2445. to evaluate performance and to monitor longterm stability of CR systems.1.4 T
12、his practice contains an alternate provision whereby industrial radiographic imaging systems may be comparativelyassessed using Lucite plastic material exposed to nominal 30 keV X-ray radiation. The RIQI for this alternate evaluation is alsoillustrated in Fig. 1, except the plaque and base plate mat
13、erials are constructed of Lucite plastic in lieu of steel. EPS values forLucite plastic are provided in Section 5 based upon the use of a 138-in. thick Lucite base plate. For high-energy X-ray applications(4 to 25 MeV), Test Method E1735 provides a similar RIQR standard practice.1.5 The values state
14、d in SI are to be regarded as the standard.1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety safety, health, and healthenvironmental practices and determine t
15、heapplicability of regulatory limitations prior to use.1.7 This international standard was developed in accordance with internationally recognized principles on standardizationestablished in the Decision on Principles for the Development of International Standards, Guides and Recommendations issuedb
16、y the World Trade Organization Technical Barriers to Trade (TBT) Committee.1 This practice is under the jurisdiction ofASTM Committee E07 on Nondestructive Testing and is the direct responsibility of Subcommittee E07.01 on Radiology (X andGamma) Method.Current edition approved July 1, 2014Nov. 1, 20
17、17. Published July 2014December 2017. Originally approved in 1980. Last previous edition approved in 20072014 asE746 - 07.E746 - 07(2014). DOI: 10.1520/E0746-07R14.10.1520/E0746-17.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of wha
18、t changes have been made to the previous version. Becauseit may not be technically 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
19、 official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States12. Referenced Documents2.1 ASTM Standards:2B152/B152M Specification for Copper Sheet, Strip, Plate, and Rolled BarE999 Guide for Controlling the Quality of Industrial
20、Radiographic Film ProcessingE1025 Practice for Design, Manufacture, and Material Grouping Classification of Hole-Type Image Quality Indicators (IQI)Used for RadiologyE1079 Practice for Calibration of Transmission DensitometersE1316 Terminology for Nondestructive ExaminationsE1735 Test Method for Det
21、ermining Relative Image Quality of Industrial Radiographic Film Exposed to X-Radiation from 4 to25 MeVE1815 Test Method for Classification of Film Systems for Industrial RadiographyE2002 Practice for Determining Total Image Unsharpness and Basic Spatial Resolution in Radiography and RadioscopyE2445
22、Practice for Performance Evaluation and Long-Term Stability of Computed Radiography SystemsE2446 Practice for Manufacturing Characterization of Computed Radiography Systems2.2 ANSI Standard3:ANSI PH2.19 Photography Density Measurements-Part 2: Geometric Conditions for Transmission Density2 For refer
23、encedASTM standards, 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 American National Standards Institute (ANSI), 25 W. 43r
24、d St., 4th Floor, New York, NY 10036, http:/www.ansi.org.Step Identification Shim Thickness, mm (in.) Hole Identification Hole Size, mm (in.)15 0.38 0.012 (0.015 0.0005) 32 0.81 0.025 (0.032 0.001)10 0.25 0.012 (0.010 0.0005) 31 0.79 0.025 (0.031 0.001)8 0.20 0.012 (0.008 0.0005) 28 0.71 0.025 (0.02
25、8 0.001)5 0.13 0.012 (0.005 0.0005) 25 0.64 0.025 (0.025 0.001)23 0.58 0.025 (0.023 0.001)20 0.50 0.025 (0.020 0.001)Hole Spacing (horizontal): 5 0.1 mm (0.2 0.004 in.) NonaccumulativeRow Spacing: 3 0.1 mm (0.2 0.004 in.)Spacing between hole sets: 5 0.1 mm (0.2 0.004 in.)All other dimensions shall b
26、e in accordance with standard engineering practice.FIG. 1 Relative Image Quality IndicatorE746 1722.3 ISO Standards3:ISO 5-2 Photography Density Measurements-Part 2: Geometric Conditions for Transmission DensityISO 7004 Photography- Industrial Radiographic Film, Determination of ISO Speed, ISO avera
27、ge gradient, and ISO gradients G2and G4 when exposed to X- and gamma-radiation3. Terminology3.1 DefinitionsThe definitions of terms relating to gamma and X-radiology in Terminology E1316 shall apply to terms usedin this practice.3.2 Definitions of Terms Specific to This Standard:3.2.1 detectoran ima
28、ging device used to store a radiographic latent image or directly convert ionizing radiation into electricalsignals in proportion to the quantity of radiation absorbed.3.2.2 cassettea device that is either flexible or rigid used to hold or protect a detector3.2.3 Relative Image Quality Indicator (RI
29、QI) an image quality measuring device that is capable of determining meaningfuldifferences between two or more radiographic imaging systems or changes of individual components of radiographic imagingsystems.3.2.4 pixel intensity value (PV)a positive integer numerical value of gray scale level of a p
30、icture data element (pixel) directlyproportional with originating digital image data values.3.2.4.1 DiscussionPV is directly related to radiation dose received by a digital detector, that is, PV is “0” if radiation dose was “0”. The number ofavailable PV integers is associated with gray scale bit de
31、pth of the digital image. For example: a 12-bit gray scale image will havea range from “0” to “4095” levels (shades) of gray (4096 total pixel value integers) and will become saturated when PV reaches“4095”.4. Significance and Use4.1 This standard provides a practice for RIQR evaluations of film and
32、 non-film imaging systems when exposed through steelor plastic materials. an absorber material. Three alternate data evaluation methods are provided in Section 9. Determining RIQRrequires the comparison of at least two radiographs or radiographic processes whereby the relative degree of image qualit
33、ydifference may be determined using the EPS plaque arrangement of Fig. 1 as a relative image quality indicator (RIQI). Inconjunction with the RIQI, a specified radiographic technique or method must be established and carefully controlled for eachradiographic process. This practice is designed to all
34、ow the determination of subtle changes in EPS that may arise to radiographicimaging system performance levels resultant from process improvements/changes or change of equipment attributes. This practicedoes not address relative unsharpness of a radiographic imaging system as provided in Practice E20
35、02. The common element withany relative comparison is the use of the same RIQI arrangement for both processes under evaluation.4.2 In addition to the standard evaluation method described in Section 9, there may be other techniques/methods in which thebasic RIQR arrangement of Fig. 1 might be utilize
36、d to perform specialized assessments of relative image quality performance. Forexample, other radiographic variables can be altered to facilitate evaluations provided these differences are known and documentedfor both processes. Where multiple radiographic process variables are evaluated, it is incu
37、mbent upon the user of this practice tocontrol those normal process attributes to the degree suitable for the application. Specialized RIQR techniques may also be usefulwith micro focus X-ray, isotope sources of radiation or with the use of non-film radiographic imaging systems. RIQR may alsobe usef
38、ul in evaluating imaging systems with alternate materials (RIQI and base plate) such as copper-nickel plastic, copper-nickel,or aluminum. When using any of these specialized applications, the specific method or techniques used shall be as specified andapproved by the cognizant engineering authority.
39、5. Relative Image Quality Indicator5.1 The materials for the RIQI and absorber should be the same. For metals use the same alloy and heat treat family, fornon-metallic materials use the same polymer system. When situations arise which preclude the use of same or “like” materials (i.e.excessive mater
40、ial grain variation affecting test results), alternate absorber materials may be used, provided the alternate materialand thickness produces the same optical density (film) or PV (for CR/DDA) as the like material of the thickness used to calculatethe EPS.5.2 The relative image quality indicator (RIQ
41、I) illustrated in Fig. 1 shall be fabricated from mild steel plate for the 200 keVevaluation method and Lucite plastic for the 30 keV evaluation method. The RIQI steps may be fabricated as a single multi-stepunit or separately and taped together to form the penetrameter type hole arrays shown in Fig
42、. 1. If tape is used, the tape shall notcover or interfere with any of the holes in the RIQI. All dimensions of the RIQI shall conform to Fig. 1.E746 1735.3 The RIQI shown in Fig. 1 consists of 14 arrays of 30 holes where all hole diameters are the same for each array. Holediameters are based upon a
43、 “multiple” of each respective step thickness; therefore, each array of 30 holes has a unique “equivalent”penetrameter sensitivity (EPS) as defined by the following relationship (E1025):EPS,%5100X 3Th2 (1)where:h = hole diameter, mmT = step thickness of IQI, mmX = thickness of test object, mmHole di
44、ameters within each EPS array are progressively smaller from the top to the bottom of Fig. 1; thus, providing descendingEPS values ranging from 1.92 % to 0.94 % for the steel method using a 19 mm (0.75 in.) thick absorber and 1.05 % to .51 %0.51 %for the plastic method (usingFig. 1 illustrates EPS v
45、alues for the steel method). Descending EPS values for Lucite plastic are:1.05 %, 1.00 %, .96 %, .91 %, .86 %, .81 %, .77 %, .73 %, .70 %, .65 %, .61 %, .58 %, .55 % and .51 % for the plaque steps ofa 35 mm (1.375 in.) thick absorber.Fig. 1.5.4 The absorber base plate shall be made of mild steel for
46、 the 200 keVkVmethod and Lucite polymethylmethacrylate (PMMA)plastic for the 30 keVkV method. Both base plates shall be at least 200 by 250 mm (8 by 10 in.) wide and long. long (for CRapplications it may be beneficial to use an absorber that covers the entire CR imaging plate to prevent creation of
47、a ghost image).The steel plate shall be 19 6 0.12 mm (0.750 6 0.005 in.) thick and the plastic plate shall be 3635 6 0.12 mm (1.375 6 0.005in.) 0.005 in.) thick. The surface finish of both absorber base plates shall be a maximum of 6.3 m (250 in.) Ra, ground finish(both faces).5.5 The RIQI shown in
48、Fig. 1 shall be placed on the radiation source side and within the approximate center of the appropriateabsorber base plate as illustrated in Fig. 2(B).6. Calibration of X-Ray Source6.1 Use a target to detector distance at least 750 mm (29.5 in.) (29.5 in.) for all exposures.FIG. 2 (A) Setup for Ene
49、rgy Calibration (B) Setup for RIQR ExposuresE746 1746.2 The voltage calibration of the X-ray source for 200keV 200kV (commonly used with steel absorber) is based on ISO7004. With an 8-mm (0.32-in.) copper filter at the X-ray tube, adjust the kilovoltage until the half value layer (HVL) in copperis 3.5 mm 3.5 mm (0.14 in.) (see Specification B152/B152M). Using a calibrated ionization chamber or similar radiationmeasurement device, make a reading of the detector with 8 mm (0.32 in.) of copper at the tube, and then,
