1、Designation: E1647 16Standard Practice forDetermining Contrast Sensitivity in Radiology1This standard is issued under the fixed designation E1647; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number
2、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 covers the design and material selection ofa contrast sensitivity measuring gauge used to determine theminimum change in materia
3、l thickness or density that may beimaged without regard to unsharpness limitations.1.2 This practice is applicable to transmitted-beam radio-graphic imaging systems (film, radioscopy, computedradiography, and digital detector array image detectors) utiliz-ing X-ray and gamma ray radiation sources.1.
4、3 The values stated in inch-pound units are to be regardedas standard. The SI units given in parentheses are for informa-tion only.1.4 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 establi
5、sh appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use. For specific safetystatements, see NIST/ANSI Handbook 114 Section 8, Code ofFederal Regulations 21 CFR 1020.40 and 29 CFR 1910.96.2. Referenced Documents2.1 ASTM Standards:2B139/B139M
6、 Specification for Phosphor Bronze Rod, Bar,and ShapesB150/B150M Specification for Aluminum Bronze Rod, Bar,and ShapesB161 Specification for Nickel Seamless Pipe and TubeB164 Specification for Nickel-Copper Alloy Rod, Bar, andWireB166 Specification for Nickel-Chromium-Iron Alloys (UNSN06600, N06601,
7、 N06603, N06690, N06693, N06025,N06045, and N06696), Nickel-Chromium-Cobalt-Molybdenum Alloy (UNS N06617), and Nickel-Iron-Chromium-Tungsten Alloy (UNS N06674) Rod, Bar, andWireE747 Practice for Design, Manufacture and Material Group-ing Classification of Wire Image Quality Indicators (IQI)Used for
8、RadiologyE1025 Practice for Design, Manufacture, and MaterialGrouping Classification of Hole-Type Image Quality In-dicators (IQI) Used for RadiologyE1255 Practice for RadioscopyE1316 Terminology for Nondestructive ExaminationsE1411 Practice for Qualification of Radioscopic SystemsE1734 Practice for
9、Radioscopic Examination of CastingsE1742 Practice for Radiographic ExaminationE2002 Practice for Determining Total Image Unsharpnessand Basic Spatial Resolution in Radiography and Radios-copyE2445 Practice for Performance Evaluation and Long-TermStability of Computed Radiography Systems2.2 Federal S
10、tandards:321 CFR 1020.40 Safety Requirements for Cabinet X-raySystems29 CFR 1910.96 Ionizing Radiation2.3 NIST/ANSI Standards:NIST/ANSI Handbook 114 General Safety Standard forInstallations Using Non-Medical X-ray and SealedGamma Ray Sources, Energies to 10 MeV42.4 ISO Standard:5ISO 192325 Duplex Wi
11、re Image Quality Indicator2.5 Other Standards:EN 462 5 Duplex Wire Image Quality Indicator(withdrawn, replaced by ISO 192325)6EN 130681 Radioscopic Testing-Part 1: Qualitative Mea-surement of Imaging Properties61This practice is under the jurisdiction of ASTM Committee E07 on Nonde-structive Testing
12、 and is the direct responsibility of Subcommittee E07.01 onRadiology (X and Gamma) Method.Current edition approved June 1, 2016. Published July 2016. Originally approvedin 1994. Last previous edition approved in 2009 as E1647 09. DOI: 10.1520/E1647-16.2For referenced ASTM standards, visit the ASTM w
13、ebsite, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from U.S. Government Printing Office Superintendent of Documents,732 N. Capitol St., NW, Mail Stop
14、: SDE, Washington, DC 20401, http:/www.access.gpo.gov.4Available fromAmerican Society for NondestructiveTesting (ASNT), P.O. Box28518, 1711 Arlingate Ln., Columbus, OH 43228-0518, http:/www.asnt.org.5Available from International Organization for Standardization (ISO), ISOCentral Secretariat, BIBC II
15、, Chemin de Blandonnet 8, CP 401, 1214 Vernier,Geneva, Switzerland, http:/www.iso.org.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13. Terminology3.1 DefinitionsDefinitions of terms applicable to this testmethod may be found in Term
16、inology E1316.4. Summary of Practice4.1 It is often useful to evaluate the contrast sensitivity of apenetrating radiation imaging system separate and apart fromunsharpness measurements. Conventional image quality indi-cators (IQIs), such as Test Method E747 wire and PracticesE1025 or E1742 plaque IQ
17、Is, combine the contrast sensitivityand resolution measurements into an overall performancefigure of merit, other methods such as included in PracticeE2002 do not address contrast specifically. Such figures ofmerit are often not adequate to detect subtle changes inimaging system performance. For exa
18、mple, in a high contrastimage, unsharpness can increase with almost no noticeableeffect upon overall image quality. Similarly, in an applicationin which the imaging system provides a very sharp image,contrast can fade with little noticeable effect upon the overallimage quality. These situations ofte
19、n develop and may gounnoticed until the system performance deteriorates belowacceptable image quality limits.5. Significance and Use5.1 The contrast sensitivity gauge measures contrast sensi-tivity independent of the imaging system spatial resolutionlimitations. The thickness recess dimensions of th
20、e contrastsensitivity gauge are large with respect to the unsharpnesslimitations of most imaging systems. Four levels of contrastsensitivity are measured: 4 %, 3 %, 2 %, and 1 %.5.2 The contrast sensitivity gauge is intended for use inconjunction with a high-contrast resolution measuring gauge,such
21、as Practice E2002, ISO 19232 5 Duplex Wire ImageQuality Indicator7, or a line-pair gauge. Such gauges measuresystem unsharpness essentially independent of the imagingsystems contrast sensitivity. Such measurements are appropri-ate for the qualification and performance monitoring of radio-graphic and
22、 radioscopic imaging systems with film, realtimedevices, Computed Radiography (CR) and Digital DetectorArrays (DDA).5.3 Radioscopic/radiographic system performance may bespecified by combining the measured contrast sensitivity ex-pressed as a percentage with the unsharpness expressed inmillimetres o
23、f unsharpness. For the duplex wire image qualityindicator, the unsharpness is equal to twice the wire diameter.For the line pair gauge, the unsharpness is equal to thereciprocal of the line-pair/mm value. As an example, animaging system that exhibits 2 % contrast sensitivity andimages the 0.1 mm pai
24、red wires of the duplex wire IQI(equivalent to imaging 5 line-pairs/millimeter resolution on aline-pair gauge) performs at a 2 %0.2 mm sensitivity level. Astandard method of evaluating overall radioscopic systemperformance is given in Practice E1411 and in EN 130681. Aconversion table from duplex wi
25、re read out to lp/mm can befound in Practice E2002. For CR system performanceevaluation, this contrast sensitivity gauge is used in PracticeE2445.6. Contrast Sensitivity Gauge Construction and MaterialSelection6.1 Contrast sensitivity gauges shall be fabricated in accor-dance with Fig. 1, using the
26、dimensions given in Table 1, Table2, and Table 3.6.2 The gauge shall preferably be fabricated from theexamination object material. Otherwise, the following materialselection guidelines are to be used:6.2.1 Materials are designated in eight groupings, in accor-dance with their penetrating radiation a
27、bsorption characteris-tics: groups 03, 02, and 01 for light metals and groups 1through 5 for heavy metals.6.2.2 The light metal groups, magnesium (Mg), aluminum(Al), and titanium (Ti), are identified as 03, 02, and 01,respectively, for their predominant constituent. The materialsare listed in order
28、of increasing radiation absorption.6.2.3 The heavy metals group, steel, copper base, nickelbase, and other alloys, are identified as 1 through 5. Thematerials increase in radiation absorption with increasingnumerical designation.6.2.4 Common trade names or alloy designations have beenused for clarif
29、ication of pertinent materials.6.3 The materials from which the contrast sensitivity gaugeis to be made is designated by group number. The gauge isapplicable to all materials in that group. Material groupings areas follows:6.3.1 Materials Group 03:6.3.1.1 The gauge shall be made of magnesium or a ma
30、g-nesium alloy, provided it is no more radio-opaque thanunalloyed magnesium, as determined by the method outlined in6.4.6.3.1.2 Use for all alloys where magnesium is the predomi-nant alloying constituent.6.3.2 Materials Group 02:6.3.2.1 The gauge shall be made of aluminum or an alumi-num alloy, prov
31、ided it is no more radio-opaque than unalloyedaluminum, as determined by the method outlined in 6.4.7The former version of the duplex wire gauge with the mark EN-462 may alsobe used. FIG. 1 General Layout of the Contrast Sensitivity GaugeE1647 1626.3.2.2 Use for all alloys where aluminum is the pred
32、omi-nant alloying constituent.6.3.3 Materials Group 01:6.3.3.1 The gauge shall be made of titanium or a titaniumalloy, provided it is no more radio-opaque than unalloyedtitanium, as determined by the method outlined in 6.4.6.3.3.2 Use for all alloys where titanium is the predominantalloying constitu
33、ent.6.3.4 Materials Group 1:6.3.4.1 The gauge shall be made of carbon steel or Type 300series stainless steel.6.3.4.2 Use for all carbon steel, low-alloy steels, stainlesssteels, and magnesium-nickel-aluminum bronze (Superston8).6.3.5 Materials Group 2:6.3.5.1 The gauge shall be made of aluminum bro
34、nze (AlloyNo. 623 of Specification B150/B150M) or equivalent ornickel-aluminum bronze (Alloy No. 630 of Specification B150/B150M) or equivalent.6.3.5.2 Use for all aluminum bronzes and all nickel alumi-num bronzes.6.3.6 Materials Group 3:6.3.6.1 The gauge shall be made of nickel-chromium-ironalloy (
35、UNS No. N06600) (Inconel9). See Specification B166.6.3.6.2 Use for nickel-chromium-iron alloy and 18 %nickel-maraging steel.6.3.7 Materials Group 4:6.3.7.1 The gauge shall be made of 70 to 30 nickel-copperalloy (Monel10) (Class A or B of Specification B164)orequivalent, or 70 to 30 copper-nickel all
36、oy, (Alloy G ofSpecification B161) or equivalent.6.3.7.2 Use for nickel, copper, all nickel-copper series orcopper-nickel series of alloys and all brasses (copper-zincalloys) and all leaded brasses.6.3.8 Materials Group 5:6.3.8.1 The gauge shall be made of tin-bronze (Alloy D ofSpecification B139/B1
37、39M).6.3.8.2 Use for tin bronzes including gun-metal and valvebronze and leaded-tin bronzes.6.4 Where the material to be examined is a composite,ceramic, or other non-metallic material, or for some reasoncannot be obtained to fabricate a gauge, an equivalent materialmay be utilized, provided it is n
38、o more radio-opaque than theexamination object under comparable penetrating radiationenergy conditions. To determine the suitability of a substitutematerial, radiographs or digital images of identical thicknessesof both materials shall be evaluated. Using film, both materialshall be on one film usin
39、g the lowest penetrating radiationenergy to be used in the actual examination. Transmissiondensitometer readings for both materials shall be in the rangefrom 2.0 to 4.0. If the optical density of the substitute materialis within + 15 % to 0 % of the examination material, thesubstitute material is ac
40、ceptable. When using a non-filmtechnique (Radioscopy, CR, or DDA), both materials shall bein the same image using the lowest penetrating radiationenergy to be used in the actual examination. The gray valuesshall be in the range of 20 % to 60 % of saturation gray level(positive image with higher gray
41、 values for less materialthickness). If the gray value of the substitute material is within+ 15 % to 0 % of the examination material, the substitutematerial is acceptable.6.4.1 All contrast sensitivity gauges shall be suitablymarked by vibro-engraving or etching. The gauge thicknessand material type
42、 shall be clearly marked.7. Imaging System Performance Levels7.1 Imaging system performance levels are designated by atwo-part measurement expressed as C(%) U(mm). The firstpart of the expression C(%) refers to the depth of theshallowest flat-bottom hole that can be reliably and repeatablyimaged. Th
43、e second part of the expression refers to thecompanion system unsharpness measurement made with aresolution gauge expressed in terms of millimetres unsharp-ness. Where contrast sensitivity is measured for both thin andthick section performance, the performance level is expressedas Cmin(%)Cmax(%)U (m
44、m) (see Practices E1255 andE1734).7.2 Each contrast sensitivity gauge has four flat-bottomrecesses that represent 1 %, 2 %, 3 %, and 4 % of the gaugetotal thickness. The shallowest recess that can be repeatablyand reliably imaged shall determine the limiting contrastsensitivity.7.3 Contrast sensitiv
45、ity measurements shall be made underconditions as nearly identical to the actual examination aspossible. Penetrating radiation energy, image formation,8Superston is a registered trademark of Superston Corp., Jersey City, NJ.9Inconel is a registered trademark of The International Nickel Co., Inc.,Hun
46、tington, WV 25720.10Monel is a registered trademark of The International Nickel Co., Inc.,Huntington, WV 25720.TABLE 1 Design of the Contrast Sensitivity GaugeGaugeThicknessJ Recess K Recess L Recess M RecessT 1%ofT 2%ofT 3%ofT 4%ofTTABLE 2 Contrast Sensitivity Gauge DimensionsGaugeSizeB DIM. C DIM.
47、 D DIM. E DIM. F,G DIM.1 0.750 in. 3.000 in. 0.250 in. 0.625 in. 0.250 in.19.05 mm 76.20 mm 6.35 mm 15.88 mm 6.35 mm2 1.500 in. 6.000 in. 0.500 in. 1.250 in. 0.500 in.38.10 mm 152.40 mm 12.70 mm 31.75 mm 12.7 mm3 2.250 in. 9.000 in. 0.750 in. 1.875 in. 0.750 in.57.15 mm 228.60 mm 19.05 mm 47.63 mm 1
48、9.05 mm4 3.000 in. 12.000 in. 1.000 in. 2.500 in. 1.000 in.76.20 mm 304.80 mm 25.40 mm 63.50 mm 25.4 mmTABLE 3 Contrast Sensitivity Gauge ApplicationGauge Size Use on Thicknesses1 Up to 1.5 in. (38.1 mm)2 Over 1.5 in. (38.1 mm) to 3.0 in. (76.2 mm)3 Over 3.0 in. (76.2 mm) to 6.0 in. (152.4 mm)4 Over
49、 6.0 in. (152.4 mm)E1647 163processing, analysis, display, and viewing variables shallaccurately simulate the actual examination environment.8. Contrast Sensitivity Gauge Measurement Steps (seeTable 1)8.1 The gauge thickness T shall be within 65 % of theexamination object thickness value at which contrast sensitiv-ity is being determined.8.2 The gauge thickness tolerance shall be within 6 1%ofthe gauge design thickness T or 0.001 in. (0.025 mm),whichever is greater.8.3 The gauge recess depth tolerance shall be within6 10 % of the design value for the shallowe
