ASTM_E_1165_-_12.pdf

Designation:E116512Standard 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 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.Scope1.1 The image quality and the resolution of X-ray imageshighly depend on the characteristics of the focal spot.Theimaging qualities of the focal spot are based on its twodimensional intensity distribution as seen from the detectorplane.1.2 This test method provides instructions for determiningthe effective size(dimensions)of standard and mini focal spotsof industrial x-ray tubes.This determination is based on themeasurement of an image of a focal spot that has beenradiographically recorded with a“pinhole”technique.1.3 This standard specifies a method for the measurement offocal spot dimensions from 50 m up to several mm of X-raysources up to 1000 kV tube voltage.Smaller focal spots shouldbe measured using EN 12543-5 using the projection of an edge.1.4 This test method may also be used to determine thepresence or extent of focal spot damage or deterioration thatmay have occurred due to tube age,tube overloading,and thelike.This would entail the production of a focal spot radio-graph(with the pinhole method)and an evaluation of theresultant image for pitting,cracking,and the like.1.5 Values stated in SI units are to be regarded as thestandard.1.6 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 establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2E1000 Guide for RadioscopyE1255 Practice for RadioscopyE2002 Practice for Determining Total Image Unsharpness inRadiologyE2033 Practice for Computed Radiology(PhotostimulableLuminescence Method)E2698 Practice for Radiological Examination Using DigitalDetector Arrays2.2 European Standards:3EN 12543-2 Non-destructive testingCharacteristics of fo-cal spots in industrial X-ray systems for use in non-destructive testingPart 2:Pinhole camera radiographicmethodEN 12543-5 Non-destructive testingCharacteristics of fo-cal spots in industrial X-ray systems for use in non-destructive testingPart 5:Measurement of the effectivefocal spot size of mini and micro focus X-ray tubes2.3 Papers:Klaus Bavendiek,Uwe Heike,Uwe Zscherpel,Uwe EwertAnd Adrian Riedo,“New measurement methods of focalspot size and shape of X-ray tubes in digital radiologicalapplications in comparison to current standards,”WC-NDT 2012,Durban,South Africa3.Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 actual focal spotthe X-ray producing area of thetarget as viewed from a position perpendicular to the targetsurface(see Fig.1).3.1.2 effective focal spotthe X-ray producing area of thetarget as viewed from a position perpendicular to the tube axisin the center of the X-ray beam(see Fig.1).3.1.3 effective size of focal spotfocal spot size measured inaccordance with this standard.4.Summary of Test Method4.1 This method is based on a projection image of the focalspot using a pinhole camera.This image shows the intensitydistribution of the focal spot.From this image the effective sizeof the focal spot is computed.A double integration of a profile1This test method is under the jurisdiction of ASTM Committee E07 onNondestructive Testing and is the direct responsibility of Subcommittee E07.01 onRadiology(X and Gamma)Method.Current edition approved June 15,2012.Published September 2012.Originallyapproved in 1987.Last previous edition approved in 2010 as E1165 04(2010).DOI:10.1520/E1165-04R12.2For 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 European Committee for Standardization(CEN),AvenueMarnix 17,B-1000,Brussels,Belgium,http:/www.cen.eu.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 across the pinhole image transforms the pinhole image into anedge profile.The X-and Y-dimension of the edge unsharpnessis used for calculation of the size of the focal spot.This methodprovides similar results as the method described in EN 12543-5using an edge target instead of a pinhole camera.The measuredeffective spot sizes correspond to the geometrical imageunsharpness values at given magnifications as measured withthe ASTM E2002 duplex wire gauge in practical images usingequation:uG5 v 2 1!(1)with geometrical unsharpness uG,focal spot size andmagnification v(seeASTM E1000 for details