ASTM_E_2903_-_13.pdf

Designation:E290313Standard Test Method forMeasurement of the Effective Focal Spot Size of Mini andMicro Focus X-ray Tubes1This standard is issued under the fixed designation E2903;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 imagingplace.1.2 This test method provides instructions for determiningthe effecting size(dimensions)of mini and micro focal spots ofindustrial X-ray tubes.It is based on the European standard,EN 125435,Non-destructive testing-Characteristics of focalspots in industrial X-ray systems for use in non-destructivetesting-Part 5:Measurement of the effective focal spot size ofmini and micro focus X-ray tubes.1.3 This standard specifies a method for the measurement ofeffective focal spot dimensions from 5 up to 300 m of X-raysystems up to and including 225 kV tube voltage,by means ofradiographs of edges.Larger focal spots should be measuredusing Test Method E1165 Standard Test Method for Measure-ment of Focal Spots of Industrial X-Ray Tubes by PinholeImaging.1.4 The same procedure can be used at higher kilovoltagesby agreement,but the accuracy of the measurement may bepoorer.1.5 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.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:2E1165 Test Method for Measurement of Focal Spots ofIndustrial X-Ray Tubes by Pinhole ImagingE1255 Practice for RadioscopyE1742 Practice for Radiographic ExaminationE1815 Test Method for Classification of Film Systems forIndustrial RadiographyE2002 Practice for Determining Total Image Unsharpness inRadiologyE2033 Practice for Computed Radiology(PhotostimulableLuminescence Method)E2446 Practice for Classification of Computed RadiologySystemsE2597 Practice for Manufacturing Characterization of Digi-tal Detector ArraysE2698 Practice for Radiological Examination Using DigitalDetector Arrays2.2 European Standards:3EN 125435 Non-destructive testingCharacteristics of fo-cal spots in industrial X-ray systems for use in non-destructive testing-Part 5:Measurement of the effectivefocal spot size of mini and micro focus X-ray tubes3.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.3.1.2 effective focal spotthe X-ray producing area of thetarget as viewed from the image plane.1This 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 1,2013.Published June 2013.DOI:10.1520/E290313.2For 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 Institute(ANSI),25 W.43rd St.,4th Floor,New York,NY 10036,http:/www.ansi.org.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 4.Summary of Test Method4.1 This method is based on indirect measurement of thefocal spot size by measuring the geometric unsharpness thenusing a geometric calculation to determine the effective focalspot dimensions(see Section 8).For this purpose,edges areimaged either on a film or by means of a radioscopic or digitalradiographic device using a relatively high geometric magni-fication.For a full description see reference below.45.Significance and Use5.1 One of the factors affecting the image quality of aradiographic image is geometric unsharpness.The degree ofgeometric unsharpness is dependent upon the focal spot size ofthe radiation source,the distance between the source and theobject to be radiographed,the distance between the object to beradiographed and the image plane(film,imaging plate,DigitalDetector Array(DDA),or radioscopic detector).This testmethod allows the user to determine the effective focal spotsize(dimensions)of the X-ray source.This result can then beused to establish source to object and object to image detectordistances appropriate for maintaining the desired degree ofgeometric unsharpness or maximum