1、Designation:E116504 (Reapproved 2010) Designation: E1165 12Standard Test Method forMeasurement of Focal Spots of Industrial X-Ray Tubes byPinhole Imaging1This standard is issued under the fixed designation E1165; the number immediately following the designation indicates the year oforiginal adoption
2、 or, 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. Scope1.1This test method provides instructions for determining the length and width d
3、imensions of line focal spots in industrial X-raytubes (see Note 1). This determination is based on the measurement of an image of a focal spot that has been radiographicallyrecorded with a “pinhole” projection/imaging technique.NOTE1Line focal spots are associated with vacuum X-ray tubes whose maxi
4、mum voltage rating does not generally exceed 500 kV.1.2This test method may not yield meaningful results on focal spots whose nominal size is less than 0.3 mm (0.011 in.). (SeeNote 2.)NOTE2The X-ray tube manufacturer may be contacted for nominal focal spot dimensions.1.3This test method may also be
5、used to determine the presence or extent of focal spot damage or deterioration that may haveoccurred due to tube age, tube overloading, and the like. This would entail the production of a focal spot radiograph (with thepinhole method) and an evaluation of the resultant image for pitting, cracking, a
6、nd the like.1.4Values stated in SI units are to be regarded as the standard. Inch-pound units are provided for information only.1.51.1 The image quality and the resolution of X-ray images highly depend on the characteristics of the focal spot. The imagingqualities of the focal spot are based on its
7、two dimensional intensity distribution as seen from the detector plane.1.2 This test method provides instructions for determining the effective size (dimensions) of standard and mini focal spots ofindustrial x-ray tubes. This determination is based on the measurement of an image of a focal spot that
8、 has been radiographicallyrecorded with a “pinhole” technique.1.3 This standard specifies a method for the measurement of focal spot dimensions from 50 m up to several mm of X-raysources up to 1000 kV tube voltage. Smaller focal spots should be measured using EN 12543-5 using the projection of an ed
9、ge.1.4 This test method may also be used to determine the presence or extent of focal spot damage or deterioration that may haveoccurred due to tube age, tube overloading, and the like. This would entail the production of a focal spot radiograph (with thepinhole method) and an evaluation of the resu
10、ltant image for pitting, cracking, and the like.1.5 Values stated in SI units 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 sa
11、fety and health practices and determine the applicability of regulatorylimitations prior to use.1This test method is under the jurisdiction of ASTM Committee E07 on Nondestructive Testing and is the direct responsibility of Subcommittee E07.01 on Radiology(X and Gamma) Method.Current edition approve
12、d June 1, 2010.15, 2012. Published November 2010.September 2012. Originally approved in 1987. Last previous edition approved in 20042010as E1165 04 (2010). DOI: 10.1520/E1165-04R102.1This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of w
13、hat 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 t
14、he official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.2. Referenced Documents2.1 ASTM Standards:2E999Guide for Controlling the Quality of Industrial Radiographic Film Processing 1000 Guide for RadioscopyE1255 Practice f
15、or RadioscopyE2002 Practice for Determining Total Image Unsharpness in RadiologyE2033 Practice for Computed Radiology (Photostimulable Luminescence Method)E2698 Practice for Radiological Examination Using Digital Detector Arrays2.2 European Standards:3EN 12543-2 Non-destructive testingCharacteristic
16、s of focal spots in industrial X-ray systems for use in non-destructivetestingPart 2: Pinhole camera radiographic methodEN 12543-5 Non-destructive testingCharacteristics of focal spots in industrial X-ray systems for use in non-destructivetestingPart 5: Measurement of the effective focal spot size o
17、f mini and micro focus X-ray tubes2.3 Papers:Klaus Bavendiek, Uwe Heike, Uwe Zscherpel, Uwe Ewert And Adrian Riedo, “New measurement methods of focal spot sizeand shape of X-ray tubes in digital radiological applications in comparison to current standards,” WC-NDT 2012, Durban,South Africa3. Termino
18、logy3.1 Definitions of Terms Specific to This Standard:3.1.1 actual focal spotthe X-ray producing area of the target as viewed from a position perpendicular to the target surface (seeFig. 2Fig. 1).3.1.2 effective focal spotthe X-ray producing area of the target as viewed from a position perpendicula
19、r to the tube axis inthe center of the X-ray beam (see Fig. 2Fig. 1).3.1.3 line focal spota focal spot whose projected pinhole image consists primarily of two curved lines (see Fig. 3). effectivesize of focal spotfocal spot size measured in accordance with this standard.4. Significance and Use4.1One
20、 of the factors affecting the quality of a radiographic image is geometric unsharpness. The degree of geometricunsharpness is dependent upon the focal size of the radiation source, the distance between the source and the object to beradiographed, and the distance between the object to be radiographe
21、d and the film. This test method allows the user to determinethe focal size of the X-ray source and to use this result to establish source to object and object to film distances appropriate formaintaining the desired degree of geometric unsharpness. Summary of Test Method4.1 This method is based on
22、a projection image of the focal spot using a pinhole camera. This image shows the intensitydistribution of the focal spot. From this image the effective size of the focal spot is computed. A double integration of a profile2For referencedASTM standards, visit theASTM website, www.astm.org, or contact
23、ASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.3Available from European Committee for Standardization (CEN), Avenue Marnix 17, B-1000, Brussels, Belgium, http:/www.cen.eu.FIG. 1 Actual/Ef
24、fective Focal SpotE1165 122across the pinhole image transforms the pinhole image into an edge profile. The X- and Y-dimension of the edge unsharpness isused for calculation of the size of the focal spot. This method provides similar results as the method described in EN 12543-5 usingan edge target i
25、nstead of a pinhole camera. The measured effective spot sizes correspond to the geometrical image unsharpnessvalues at given magnifications as measured with the ASTM E2002 duplex wire gauge in practical images using equation:uG5Fv 1! E1165-12_1 (1)FIG. 2 Exays the emplectr fons are accelera ted from
26、 the filam Ment to the target in twosepaurate paths (see Sketch 1). Electronsemitted at the front of the Efilamfenct traivel prim Focarily al Spot Leng Path A, and electrons em Witted at the backs wide ofthefilamen t travel primarily along Path B. Note that these two paths i Integrsectat a certad Li
27、n point; this is the point at which the ta Prgetis posfitioned. As a result, the pinhol (ILP) Me picture of the fod (cal spot shows two linesthat correspond with the intuersections of Paths Aand B at the target (see Sketch 2).(e) Image of a double line Focal Spot with the Location and Size of the Li
28、ne Profile in Width Direction.(f) Integrated Line Profile with Markers (blue) for 16 % and 84 % of the Profile Intensity, Markers (green) for 0 % and 100 % Extrapolation and the Extrapolation Line(dotted black) for the Width Direction.E1165 123with geometrical unsharpness uG, focal spot size F and m
29、agnification v (see ASTM E1000 for details of this equation). For afull description see Reference 2.3.4.2 Additionally, a simplified test method is described in the annex A for users of X-ray tubes who may not intend to use apinhole camera. This alternative method is based on the edge method in acco
30、rdance with EN 12543-5 using a plate hole IQI asdescribed in ASTM E1025 or E1742 instead of a pinhole camera.5. Significance and Use5.1 One of the factors affecting the quality of radiologic images is the geometric unsharpness. The degree of geometricunsharpness is dependent on the focal spot size o
31、f the radiation source, the distance between the source and the object to beradiographed, and the distance between the object to be radiographed and the detector (imaging plate, Digital Detector Array(DDA) or film). This test method allows the user to determine the effective focal size of the X-ray
32、source. This result may thenbe used to establish source to object and object to detector distances appropriate for maintaining the desired degree of geometricunsharpness and/or maximum magnification for a given radiographic imaging application. Some ASTM standards require thisvalue for calculation o
33、f a required magnification, for example, E1255, E2033, and E2698.6. Apparatus5.16.1 Pinhole DiaphragmThe pinhole diaphragm shall conform to the design and material requirements of Table 1 and Fig.1and Fig. 3.5.26.2 CameraThe pinhole camera assembly consists of the pinhole diaphragm, the shielding ma
34、terial to which it is affixed, andany mechanism that is used to hold the shield/diaphragm in position (jigs, fixtures, brackets, and the like; see The pinhole cameraassembly consists of the pinhole diaphragm, the shielding material to which it is affixed, and any mechanism that is used to holdthe sh
35、ield/diaphragm in position (jigs, fixtures, brackets, and the like).6.3 Alignment and Position of the Pinhole CameraThe angle between the beam direction and the pinhole axis (see Fig. 4).5.3FilmIndustrial type extra fine grain. No intensifying screens are to be used. The film shall be processed in a
36、ccordance withGuide E999) shall be smaller than 61.5. When deviating from Fig. 4, the direction of the beam shall be indicated. The incidentface of the pinhole diaphragm shall be placed at a distance m from the focal spot so that the variation of the magnification overthe extension of the actual foc
37、al spot does not exceed 65 % in the beam direction. In no case shall this distance be less than 100mm.6.4 Position of the Radiographic Image DetectorThe radiographic image detector (film, imaging plate or DDA) shall beplaced normal to the beam direction at a distance n from the incident face of the
38、pinhole diaphragm determined from the applicablemagnification according to Fig. 5 and Table 2.5.4Image Measurement Apparatus This apparatus is used to measure the size of the image of the focal spot. The apparatusshall be an optical comparator with built-in graticule with 0.1 mm or .001 in., or both
39、 divisions and magnification of 53 to 103(or equivalent).6.6.5 Radiographic Image DetectorAnalogue or digital radiographic image detectors may be used, provided sensitivity,dynamic range and detector unsharpness allow capturing of the full spatial size of the focal spot image without detector satura
40、tion.TABLE 1 Pinhole Diaphragm Design Requirements (Dimension)ANOTE 1The pinhole diaphragm shall be made from one of thefollowing materials: (1) An alloy of 90 % gold and 10 % platinum,(2) Tungsten, (3) Tungsten carbide, (4) Tungsten alloy, (5) Platinum and10 % Iridium Alloy, or (6) Tantalum.NFominc
41、al D Spot Simzension ofFocal Spot,mm (in.)BNominalDiameter of Diaphragm POpening,mm (in.)Required “D” and “L” DimensD LDHeight Hm0.3 to1.2 (0.011 to 0.046) incl 0.030 (0.0011) 0.030 6 0.005 (0.0011 6 0.0002)0.05 to 0.3 10 6 5 0.030 (0.0011) 0.030 6 0.0050 6 0.0002)1.2 to 2.5 (0.046 to 0.097) incl 0.
42、075 (0.0029) 0.075 6 0.005(0.0029 6 0.0002)0.350 60.3to0.8 30 6 5 75 (0.0029) 0.075 6 0.005(0.0029 6 0.0002)2.5 (0.097) 0.100 (0.0039) 0.100 6 0.005 (0.0039 6 0.0002)0.500 60.8 100 6 5 0.100 (0.0039) 0.100 6 0.00500 6 0.0002)ASee Fig. 1 3.BNominal focal spot dimensions may be obtained from the X-ray
43、 tube manufac-turer.E1165 124The maximum allowed detector unsharpness is given by the geometrical unsharpness uGof the pinhole and the pinhole diameterP. It is calculated according to (see Fig. 5).uG5 P1 1 n/m! E1165-12_2 (2)6.5.1 The detector unsharpness shall be determined with the duplex wire IQI
44、 in accordance with ASTM E2002. The minimumprojected length and width of the focal spot image should be covered always by at least 20 detector pixels in digital images. Thesignal-to-noise ratio of the focal spot image (ratio of the maximum intensity value inside the focal spot and the standard devia
45、tionof the background signal outside) should be at least 50. The maximum intensity inside the focal spot should be above 30 %, butlower than 90 % of the maximum linear detector output value. The grey value resolution of the detector shall be in minimum 12Bit.6.5.2 Imaging plate systems (Computed Rad
46、iography, CR) or digital detector arrays (DDA) may be used as digital imagedetectors following practices E2033 or E2698. The pixel values shall be linear to the dose.6.5.3 If radiographic film is used as image detector, it shall meet the requirements of E1815 film system class I or Special andFIG.12
47、PinExample for the Measurement olf Effe Dctive Focal Spot Lengthr and Width with the Integm Dratesd Ligne Profile (ILP)Method(a) Image of a double line Focal Spot with the Location and Size of the Line Profile in Length Direction.(b) Line Profile in the direction of the large arrow averaged over the
48、 dotted rectangle of Fig. 2a.(c) Integrated Line Profile with Markers (blue) for 16 % and 84 % of the Profile Intensity, Markers (green) for 0 % and 100 % Extrapolation and the Extrapolation Line(dotted black), corresponding to the Klasens method of E1000.(d) Pseudo 3D Image of the Focal Spot; the l
49、arge arrow points in the direction of the Line Profile.(e) Image of a double line Focal Spot with the Location and Size of the Line Profile in Width Direction.(f) Integrated Line Profile with Markers (blue) for 16 % and 84 % of the Profile Intensity, Markers (green) for 0 % and 100 % Extrapolation and the Extrapolation Line(dotted black) for the Width Direction.E1165 125shall be packed in low absorption cassettes using no screens. The film shall be exposed to a maximum optical density between 1.5and 2.5. The film shall be digitized with a maximum pi
