1、Designation: E746 17E746 18Standard 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, in the case of r
2、evision, 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 systems may be comparat
3、ively 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 5.3 of this practice. Figure 1 illustratesa relative image qualit
4、y indicator (RIQI) that has four different plaque thicknesses (0.015, 0.010, 0.008, and 0.005 in.) sequentiallypositioned (from top to bottom) on an absorber plate of a specified material and thickness. The four plaques contain a total of 14different arrays of penetrameter-type hole sizes designed t
5、o render varied conditions of threshold visibility when exposed to theappropriate radiation. Each “EPS” array consists of 30 identical holes; thus, providing the user with a quantity of thresholdsensitivity levels suitable for relative image qualitative response comparisons. There are two standard m
6、aterials (steel and plastic)specified herein for the RIQI and absorber. For special applications the user may design a non-standard RIQI-absorberconfiguration; however the RIQI configuration shall be controlled by a drawing similar to Fig. 1. Use of a non-standardRIQI-absorber configuration shall be
7、 described in the users written technique and approved by the CEO.1.2 This practice is not intended to qualify the performance of a specific radiographic technique nor for assurance that aradiographic technique will detect specific discontinuities in a specimen undergoing radiographic examination.1.
8、3 This practice is not intended to be used to classify or derive performance classification categories for radiographic imagingsystems. For example, performance classifications of radiographic film systems may be found within Test Method E1815, andmanufacturer characterization of computed radiograph
9、y (CR) systems may be found in Practice E2446. However, the RIQI andabsorber described in this practice are used by Practice E2446 for manufacturer characterization of computed radiography (CR)systems and by Practice E2445 to evaluate performance and to monitor long term stability of CR systems.1.4
10、For high-energy X-ray applications (4 to 25 MeV), Test Method E1735 provides a similar RIQR standard practice.1.5 The values stated 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 responsibi
11、lityof the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability ofregulatory limitations prior to use.1.7 This international standard was developed in accordance with internationally recognized principles on standardizationestabli
12、shed 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:2B152/B152M Specification for Copper Sheet, Strip, Plate, and Roll
13、ed BarE999 Guide for Controlling the Quality of Industrial 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 Densitometers1 This practice
14、 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 Nov. 1, 2017Feb. 1, 2018. Published December 2017February 2018. Originally approved in 1980. Last previous editi
15、on approved in 20142017as E746 - 07E746(2014). -17. DOI: 10.1520/E0746-17.10.1520/E0746-18.2 For referencedASTM 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 Sum
16、mary page on the ASTM website.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 technically possible to adequately depict all changes accurately, ASTM recommend
17、s 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 Box C700, West Conshohocken, PA 19428-2959. United States1E1316 Terminology
18、for Nondestructive ExaminationsE1735 Test Method for Determining 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 Basi
19、c Spatial Resolution in Radiography and RadioscopyE2445 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:
20、Geometric Conditions for Transmission Density2.3 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 average gradient, and ISO gradients G2and G4 when exposed
21、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 Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http:/www.ansi
22、.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 (0.028 0.001)5 0.13 0.012 (0.005 0.0005) 25 0.64 0.025 (0
23、.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 be in accordance with standard engineering practice.F
24、IG. 1 Relative Image Quality IndicatorE746 1823.2 Definitions of Terms Specific to This Standard:3.2.1 detectoran imaging 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
25、 device that is either flexible or rigid used to hold or protect a detector3.2.3 Relative Image Quality Indicator (RIQI) an image quality measuring device that is capable of determining meaningfuldifferences between two or more radiographic imaging systems or changes of individual components of radi
26、ographic imagingsystems.4. Significance and Use4.1 This standard provides a practice for RIQR evaluations of film and non-film imaging systems when exposed through anabsorber material. Three alternate data evaluation methods are provided in Section 9. Determining RIQR requires the comparisonof at le
27、ast two radiographs or radiographic processes whereby the relative degree of image quality difference may be determinedusing the EPS plaque arrangement of Fig. 1 as a relative image quality indicator (RIQI). In conjunction with the RIQI, a specifiedradiographic technique or method must be establishe
28、d and carefully controlled for each radiographic process. This practice isdesigned to allow the determination of subtle changes in EPS that may arise to radiographic imaging system performance levelsresultant from process improvements/changes or change of equipment attributes. This practice does not
29、 address relativeunsharpness of a radiographic imaging system as provided in Practice E2002. The common element with any relative comparisonis 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
30、be other techniques/methods in which thebasic RIQR arrangement of Fig. 1 might be utilized 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 documentedfo
31、r both processes. Where multiple radiographic process variables are evaluated, it is incumbent 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
32、 radiation or with the use of non-film radiographic imaging systems. RIQR may alsobe useful in evaluating imaging systems with alternate materials (RIQI and base plate) such as plastic, copper-nickel, or aluminum.When using any of these specialized applications, the specific method or techniques use
33、d shall be as specified and approved bythe cognizant engineering authority.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 ar
34、ise which preclude the use of same or “like” materials (i.e.excessive material 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 thick
35、ness used to calculatethe EPS.5.2 The RIQI steps may be fabricated as a single multi-step unit or separately and taped together to form the penetrameter typehole arrays shown in Fig. 1. If tape is used, the tape shall not cover or interfere with any of the holes in the RIQI. All dimensionsof the RIQ
36、I shall conform to Fig. 1.5.3 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 “multiple” of each respective step thickness; therefore, each array of 30 holes has a unique “equivalent”penetrameter sensitiv
37、ity (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 diameters within each EPS array are progressively smaller from the top to the bottom of Fig. 1; thus, providing descendingEPS val
38、ues ranging from 1.92 % to 0.94 % for the steel method using a 19 mm (0.75 in.) thick absorber and 1.05 % to 0.51 %for the plastic method using a 35 mm (1.375 in.) thick absorber.5.4 The absorber base plate shall be made of mild steel for the 200 kV method and polymethylmethacrylate (PMMA) plasticfo
39、r the 30 kV method. Both base plates shall be at least 200 by 250 mm (8 by 10 in.) wide and long (for CR applications it maybe beneficial to use an absorber that covers the entire CR imaging plate to prevent creation of a ghost image). The steel plate shallbe 19 6 0.12 mm (0.750 6 0.005 in.) thick a
40、nd the plastic plate shall be 35 6 0.12 mm (1.375 6 0.005 in.) thick. The surfacefinish of both absorber base plates shall be a maximum of 6.3 m (250 in.) Ra, ground finish (both faces).E746 1835.5 The RIQI shown in Fig. 1 shall be placed on the radiation source side and within the approximate cente
41、r 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.) for all exposures.6.2 The voltage calibration of the X-ray source for 200kV (commonly used with steel absorber) is based on ISO 7004. Wit
42、han 8-mm (0.32-in.) copper filter at the X-ray tube, adjust the kilovoltage until the half value layer (HVL) in copper is 3.5 mm (0.14in.) (see Specification B152/B152M). Using a calibrated ionization chamber or similar radiation measurement device, make areading of the detector with 8 mm (0.32 in.)
43、 of copper at the tube, and then, make a second reading with a total of 11.5 mm (0.45in.) of copper at the tube as shown in Fig. 2(A).6.3 The voltage calibration of the X-ray source for 30kV (commonly used with plastic absorber) is based on ISO 7004 methodfor 100kV calibration, modified for 30kV. Wi
44、th a 7.62-mm (0.30-in.) aluminum filter at the X-ray tube port, adjust thekilovoltage until the half value layer (HVL) in aluminum is 1.52 mm (0.06 in.). That is, the intensity of the X-ray beam with9.14mm (0.36in.) aluminum at the tube port shall be one-half that with 7.62mm (0.30in.) aluminum at t
45、he tube port.6.4 For both 200kV and 30kV X-ray beam calibration methods, calculate the ratio of the two readings. If this ratio is not 2,adjust the kilovoltage up or down and repeat the measurement until a ratio of 2 (within 5 %) is obtained. Record the X-ray machinevoltage settings and use these sa
46、me values for the RIQR evaluations. Prior to RIQR performance evaluations for both 200kV and30kV methods, remove all HVL and filter materials at the X-ray tube port.6.5 Use of other X-ray voltages or gamma spectra other than defined above shall employ a similar calibration method whichshall be docum
47、ented in the users written technique and approved by the CEO.7. Procedure7.1 BasicUse the physical set up as shown in Fig. 2(B). Position the X-ray tube directly over the approximate center of theRIQI and detector cassette. The plane of the detector and RIQI must be normal to the central ray of the
48、X-ray beam. Use adiaphragm at the tube to limit the field of radiation to the film area.FIG. 2 (A) Setup for Energy Calibration (B) Setup for RIQR ExposuresE746 1847.2 Source-to-detector distance (SDD) is based upon achieving a geometrical unsharpness (Ug) of 0.05 mm (0.002 in.) or lesson a 35 mm (1
49、.375 in.) thick plastic absorber plate for 30kV and a 19 mm (0.750 in.) thick steel absorber plate for 200kV.Calculate the minimum SDD, in millimeters, as follows:For plastic, t=35 mm 1.375 in.!, SDD = 6981t (2)For steel, t=19 mm 0.75 in.!, SDD = 3811t (3)where:SDD = source-to-detector distance, mm, and = focal spot size, mm.The SDD shall be the larger of this calculated value and 1 m (39.4 in.).7.3 Detector Cassettes and Screens (film and CR)Low absorption cassettes shall be used to maximize the
