1、Designation: E1114 091Standard Test Method forDetermining the Size of Iridium-192 Industrial RadiographicSources1This standard is issued under the fixed designation E1114; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of
2、 last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1NOTEEditorially corrected 2.2 and Figure 4 in June 2011.1. Scope1.1 This test method covers the determination of the size ofan I
3、ridium-192 radiographic source. The determination isbased upon measurement of the image of the Iridium metalsource in a projection radiograph of the source assembly andcomparison to the measurement of the image of a referencesample in the same radiograph.1.2 The values stated in either SI units or i
4、nch-pound unitsare to be regarded separately as standard. The values stated ineach system may not be exact equivalents; therefore, eachsystem shall be used independently of the other. Combiningvalues from the two systems may result in non-conformancewith the standard.1.3 This standard does not purpo
5、rt 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 and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2E999
6、 Guide for Controlling the Quality of Industrial Radio-graphic Film ProcessingE1316 Terminology for Nondestructive ExaminationsE1815 Test Method for Classification of Film Systems forIndustrial RadiographyE2445 Practice for Qualification and Long-Term Stabilityof Computed Radiology SystemsE2597 Prac
7、tice for Manufacturing Characterization of Digi-tal Detector Arrays2.2 Other International Standards:EN 12679:2000 Industrial RadiographyRadiographicMethod for the Determination of the Source Size forRadioisotopes33. Terminology3.1 For definitions of terms relating to this test method, referto Termi
8、nology E1316.4. Significance and Use4.1 One of the factors affecting the quality of a radiographicimage is geometric unsharpness. The degree of geometricunsharpness is dependent upon the size of the source, thedistance between the source and the object to be radiographed,and the distance between the
9、 object to be radiographed and thefilm or digital detector. This test method allows the user todetermine the size of the source and to use this result toestablish source to object and object to film or detectordistances appropriate for maintaining the desired degree ofgeometric unsharpness.NOTE 1The
10、 European standard CEN EN 12579 describes a simplifiedprocedure for measurement of source sizes of Ir-192, Co-60 and Se-75.The resulting source size of Ir-192 is comparable to the results obtained bythis test method.5. Apparatus5.1 Subject Iridium-192 Source, the source size of which isto be determi
11、ned. The appropriate apparatus and equipment forthe safe storage, handling, and manipulation of the subjectsource, such as a radiographic exposure device (also referred toas a gamma ray projector or camera), remote control, sourceguide tube, and source stop are also required.5.2 Reference Sample (se
12、e Figs. 1-3)The referencesample shall be of material which is not radioactive. Therecommended material is Iridium. However, substitutes such asplatinum, tungsten or other material of similar radiopacity maybe used. The sample should be of the same geometric shape as1This test method is under the jur
13、isdictioin of ASTM Committee E07 onNondestructive Testing and is the direct responsibility of Subcommittee E07.01 onRadiology (X and Gamma) Method.Current edition approved June 1, 2009. Published July 2009. Originally approvedin 1986. Last previous edition approved in 2003 as E1114 03. DOI: 10.1520/
14、E1114-09E01.2For referenced ASTM standards, visit the ASTM website, 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 American National Standards Insti
15、tute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.the subject source, should be approximately the same size asthe subject source, and should be positioned on
16、 or within ashim or envelope to simulate the source capsule wall. Theresulting radiographic contrast, with reference to adjacentbackground density of the image of the reference sample,should be approximately the same as that of the subject source.The actual dimensions of the reference sample should
17、bedetermined to the nearest 0.025 mm (0.001 in.).5.3 X-ray Generator, capable of producing a radiationintensity (roentgen per hour at one metre) at least ten timesgreater than that produced by the subject source. Examples oftypical X-ray generator output requirements that satisfy thiscriterion are p
18、resented in Table 1.5.4 Film systemsOnly film systems having cognizantengineering organization approval or meeting the system classrequirements of Test Method E1815, for system classes I, II orSpecial, shall be used. Selection of film systems should bedetermined by such factors as the required radio
19、graphic qualitylevel, equipment capability, materials and so forth. The filmsystem selected shall be capable of demonstrating the requiredimage quality. No intensifying screens shall be used. Radio-graphic films shall be processed in accordance with GuideE999.5.5 Image Measurement ApparatusThis appa
20、ratus is usedto measure the size of the image of the spot. The apparatusshall be an optical comparator with built-in graticule with 0.1mm divisions or 0.001 in. divisions and magnification of 53 to103.5.6 Digital DetectorsDigital detectors, which are eitherimaging plates or digital detector arrays,
21、may be used as filmreplacement. The digital detector shall possess a pixel pitchwhich is at least 40 times smaller than the nominal source sizeto measure and a basic spatial resolution smaller than120 of thenominal source size. The basic spatial resolution shall bemeasured in accordance with the pro
22、cedure of Practice E2597for DDAs or Practice E2445 for the imaging plate scannersystem or taken from manufacturer statements. In the area offree beam a detector SNRD 100 shall be achieved. Themeasurement procedure of the SNR shall be in accordance withFIG. 1 Reference Sample in Standard Source Encap
23、sulationFIG. 2 Alternate Reference Sample ArrangementFIG. 3 Alternate Reference Sample ArrangementTABLE 1 Examples of Typical X-ray Generator OutputRequirements for Related Iridium192Source ActivitiesSubject Iridium192SourceRadiationTypical X-ray GeneratorOutput RequirementsActivity(Curie)Output(R/h
24、 at 1 m)Potential Current30 14.4 160 kV 5 mAor 200 kV 3 mA100 48.0 160 kV 10 mAor 250 kV 4 mA200 96.0 160 kV 20 mAor 250 kV 8 mAor 300 kV 6 mAE1114 0912the procedure of Practice E2597 for DDAs or Practice E2445for the imaging plate scanner system.5.7 Evaluation of Digital ImagesDigital images shall
25、beevaluated by an image processing software with contrast,brightness, profile and zoom function. The digital images shallbe magnified at the monitor to a degree that allows the imageviewing with at least one pixel of the image at one pixel of themonitor.6. Procedure6.1 Set up the exposure arrangemen
26、t as shown in Figs. 4-7.Position the X-ray tube directly over the center of the film ordigital detector. The film or detector plane must be normal tothe central ray of the X-ray beam. The X-ray spot should be0.90 m (36 in.) from the film or detector. Position the referencesample and apparatus used t
27、o locate the subject source (sourcestop) as close together as possible and directly over the centerof the film or detector. The plane of the source stop andreference sample must be parallel to the film or detector andnormal to the central ray of the X-ray beam. The source stopand reference sample sh
28、ould be 0.15 m (6 in.) from the film ordetector. The source stop should be connected to the radio-graphic exposure device by the shortest source guide tubepracticable in order to minimize fogging of the film or detectorduring source transit.6.2 Place identification markers to be imaged on the film o
29、rdetector to identify, as a minimum, the identification (serialnumber) of the subject source, the size of the reference sample,the identification of the organization performing the determi-nation, and the date of the determination. Care should be takento ensure that the images of the subject source
30、and referencesample will not be superimposed on the image of the identifi-cation markers.6.3 ExposureSelect the X-ray tube potential (kV), X-raytube current (mA) and exposure time such that the density inthe image of the envelope surrounding the reference sampledoes not exceed 3.0 and that the densi
31、ty difference between theimage of the reference sample and the image of the envelopesurrounding the reference sample is at least 0.10. In digitalimages the linear grey value difference between the image ofthe reference sample and the image of the envelope surround-ing the reference sample shall be f
32、ive times larger than theimage noise s(s = standard deviation of the grey valuefluctuations in an area of homogeneous exposure, measured ina window of at least 20 by 55 pixels) in a homogeneousneighbor area.NOTE 2The actual parameters that will produce acceptable resultsmay vary between X-ray units,
33、 and trial exposures may be necessary.6.3.1 Energize the X-ray generator and, at the same time,manipulate the subject source into the exposure position in thesource stop. It is important that this be performed as quickly aspossible to minimize fogging of the film or detector.6.3.2 At the conclusion
34、of the exposure time, deenergize theX-ray generator and, at the same time, return the subject sourceto the proper shielded storage position.6.3.3 Process the film or read out the digital detector arrayor scan the imaging plate.7. Measurement of Source Dimensions7.1 When viewing the film radiograpgh,
35、 view it with suffi-cient light intensity for adequate viewing. Using an opticalcomparator with built-in graticule as described in 5.5, measurethe linear dimensions of the image of the spot size of thesubject source and the reference sample. Take measurementsFIG. 4 Typical Exposure ArrangementFIG. 5
36、 Typical Arrangement Using a Specially Designed GuideTubeFIG. 6 Typical Arrangement Using a Standard Guide Tube andSpecial Positioning FixtureE1114 0913from the perceptible edges of the image. When performing thephysical measurements with the optical comparator, the actualmeasured values shall be to
37、 the nearest graduation on thegraticule scale being used.7.2 When viewing the digital image, view it in a darkenedroom and use a bright monitor with at least 250 cd/m2. Use theprofile function of the image processing software for sizemeasurement in digital images after proper brightness andcontrast
38、adjustment.7.3 The source size for a given technique is the maximumprojected dimension of the source in the plane perpendicular toa line drawn from the source to the object being radiographed.Therefore, sufficient measurements of the image of the Iridiummust be made to determine the size of the sour
39、ce in anyorientation. Sections 7.4-7.7 serve as examples.7.4 Uniform Right Circular Cylinder (see Fig. 8)Determine the source size of a uniform right circular cylindri-cal source by measuring the diameter, d, the height, h, and thediagonal, m, as illustrated in Fig. 8 and computing the actualdimensi
40、ons as described in 8.1.7.5 Sphere (see Fig. 9)Determine the size of a sphericalsource by measuring the diameter, d, as illustrated in Fig. 9 andcomputing the actual dimension as described in 8.1.7.6 Nonuniform Stack of Right Circular Cylinders (see Fig.10)Determine the size of a nonuniform stack of
41、 right circularcylindrical components of a source by measuring the intrinsicdiameter, d, the height, h, and the effective maximum dimen-sion, m, as illustrated in Fig. 10 and computing the actualdimensions as described in 8.1.7.7 Separated Stack of Right Circular Cylinders (see Fig.11)Determine the
42、size of a separated stack of right circularcylindrical components of a source by measuring the intrinsicdiameter, d, the effective height, h, and the effective maximumdimension, m, as illustrated in Fig. 11 and computing the actualdimensions as described in 8.1.8. Calculation and Evaluation8.1 Measu
43、re the linear dimension of interest in the subjectsource image and measure the same linear dimension in thereference sample image (that is, the diameter of each). Theactual dimension of the subject source is computed from thefollowing:FIG. 7 Typical Arrangement Using Reference Sample Positioning Dev
44、iceFIG. 8 Uniform Right Circular CylinderFIG. 9 SphereFIG. 10 Nonuniform Cylindrical StackFIG. 11 Separated Cylindrical StackE1114 0914a 5 bc/dwhere:a = actual dimension of the subject source,b = actual dimension of the reference sample,c = measured dimension of the subject source image, andd = meas
45、ured dimension of the reference sample image.9. Report9.1 A report of the size of an Iridium-192 source shouldindicate the model number and serial number of the source, thename of the organization making the determination, the datethe determination was made, a description of the shape of thesource (
46、or an appropriate sketch), and the calculated actualdimensions. The actual radiograph should accompany thereport.10. Precision and Bias10.1 PrecisionIt is not possible to specify the precision ofthe procedure in this test method for measuring the size ofIridium-192 radiographic sources because round
47、 robin testinghas not yet been accomplished.10.2 BiasNo information can be presented on the bias ofthe procedure in this test method for measuring the size ofIridium-192 radiographic sources because round robin testinghas not yet been accomplished.11. Keywords11.1 cylinder(s); Iridium 192; radiograp
48、hic source; refer-ence sample; source size; sphereASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent right
49、s, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comme
