1、Designation: F 640 07Standard Test Methods forDetermining Radiopacity for Medical Use1This standard is issued under the fixed designation F 640; 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
2、 parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.1. Scope*1.1 These test methods cover the determination of theradiopacity
3、of materials and products utilizing X-ray basedtechniques, including fluoroscopy, angiography, CT (computedtomography) and DEXA, also known as DXA, (dual energyX-ray absorptiometry). The results of these measurements arean indication of the likelihood of locating the product withinthe human body.1.2
4、 Types of TestsThere are three methods of tests de-scribed, differing in the method of determining radiopacity.1.2.1 Method ARadiopacity is (1) qualitatively deter-mined by viewing image(s) of a test sample and the imagebackground, with or without the use of a body mimic, or (2)quantitatively determ
5、ined as a specific difference in opticaldensity or pixel intensity between the image of a test sampleand the image background, with or without the use of a bodymimic.1.2.2 Method BRadiopacity is determined by (1) qualita-tively comparing image(s) of a test sample and a user-definedstandard without t
6、he use of a body mimic, or (2) quantitativelydetermining the specific difference in optical density or pixelintensity between the image of a test sample and the image ofa user-defined standard without the use of a body mimic.1.2.3 Method CRadiopacity is determined by (1) qualita-tively comparing ima
7、ge(s) of a test sample and a user-definedstandard with the use of body mimic or (2) quantitativelydetermining the specific difference in optical density or pixelintensity between the image of a test sample and the image ofa user-defined standard with the use of a body mimic.1.3 The values stated in
8、SI units are to be regarded as thestandard.1.4 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 regulato
9、ry limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2B 209 Specification for Aluminum and Aluminum-AlloySheet and PlateD 3182 Practice for RubberMaterials, Equipment, andProcedures for Mixing Standard Compounds and Prepar-ing Standard Vulcanized SheetsE94 Guide for Radiographic Exa
10、minationE 1316 Terminology for Nondestructive ExaminationsF 647 Practice for Evaluating and Specifying ImplantableShunt Assemblies for Neurosurgical Application3. Terminology3.1 DefinitionsFor definitions of terms relating to X-rayprocedures, refer to Terminology E 1316.3.2 Descriptions of Terms:3.2
11、.1 body mimic, na piece of material, a phantom, acadaver, or an animal utilized to mimic the appropriate X-rayattenuation through a particular part of the human body.3.2.2 digital resolution, nthe number of pixels per inch ina digital image.3.2.2.1 DiscussionThis may be different in the x and ydirec
12、tions3.2.3 grayscale range, nthe number of levels in pixelintensity resolved in the digital image.3.2.3.1 DiscussionThis is normally 256 levels in an 8-bitgrayscale image3.2.4 optical density, nthe range of values of opticaldensity as measured by a densitometer; in this test method theexpected range
13、 is 0.50 to 1.50.3.2.5 optical density difference, nthe difference in opticaldensity units between two regions or objects in an image,reported to at least two digits to the right of the decimal point.1These test methods are under the jurisdiction of ASTM Committee F04 onMedical and Surgical Material
14、s and Devices and are the direct responsibility ofSubcommittee F04.15 on Material Test Methods.Current edition approved March 1, 2007. Published March 2007. Originallyapproved in 1979. Last previous edition approved in 2000 as F 640 79 (2000).2For referenced ASTM standards, visit the ASTM website, w
15、ww.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.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive
16、, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.2.6 pixel intensity, nthe grayscale level of a pixelbetween 0 and 255, as determined by the digital analysisprogram.3.2.7 pixel intensity difference, nthe difference in gray-scale level between two regions or objects in an image,report
17、ed to within the significance capability of the digitalanalysis program.3.2.8 user-defined standard, na comparison standard se-lected by the user.3.2.8.1 DiscussionThis standard may be an existing medi-cal product or a material in a particular form, it may be acommercially available standard, or it
18、may be one developedby the user.4. Summary of Test Methods4.1 The test specimen is placed so it sits in the middle of theX-ray image area in the X-ray imaging system. X-ray imagesare made at specified voltages, times, and currents that aretypical of those used in the X-ray diagnosis of humans.Prefer
19、red settings are those appropriate for the product and forthe particular area of body interest (for example, leg, heart, andso forth). The radiopacity of the test specimen is evaluated interms of the criteria described for the test method selected.5. Significance and Use5.1 These methods are intende
20、d to determine whether amaterial, product, or part of a product has the degree ofradiopacity desired for its application as a medical device in thehuman body.5.2 These methods allow for both qualitative and quantita-tive evaluation in different comparative situations.6. Apparatus6.1 X-Ray Imaging Sy
21、stem.6.2 X-Ray Film or Digital Image Acquisition SystemThefilm or digital imaging system must be appropriate for theimaging conditions used. A grid may be used.6.3 Body Mimic for Methods A and C (not all-inclusive):6.3.1 Aluminum SheetA 10.0 6 0.15-mm thick aluminumsheet may be used. If so specified
22、 in the standard for themedical device, a 15.0 6 0.15-mm thick sheet may be used.The aluminum sheet shall be $99 % in purity, or type 1100 orpurer, in accordance with Specification B 209.6.3.2 AnimalAn appropriate animal, or portion of appro-priate animal, with which to perform the tests may be used
23、.6.3.3 CadaverA human body, or portion of human body,with which to perform the tests may be used.6.3.4 Calibration StandardFor digital analysis, a standardthat creates a completely clear area and a completely opaquearea in the image to allow setting of the full range of 256grayscale levels.6.3.5 Met
24、al, Plastic, or CompositeA metal, plastic, orcomposite material of appropriate dimensions may be used.6.3.6 PhantomA device that mimics a portion of the bodymay be used; this device may be as complex as a manufacturedtorso with appropriate densities representing all portions of theanatomy within the
25、 torso, or may be as simple as a tub of water.6.3.7 Step WedgeA step wedge may be used if it has therequisite thickness steps.6.4 Rubber BlanketsBlankets incorporating X-ray absorb-ers may be used to mask areas outside that covered by the bodymimic material (this prevents undercutting). Lead sheets
26、mayalso be used for masking.6.5 Back-Scatter Protection, as described in Guide E94,oras appropriate with the specific X-ray imaging system.6.6 DensitometerThe densitometer shall be capable ofmeasuring the optical density over the range of 0.0 to 3.0optical density units, minimum. It shall have a mea
27、suringaccuracy of 60.02 optical density units or better. The densi-tometer shall have been calibrated within six months previ-ously by a method and calibration standard traceable to theNational Institute of Standards and Technology. This is notrequired if digital analysis is used.6.7 Step Tablet,3fo
28、r calibrating densitometers. This is notrequired if digital analysis is used.7. Test Specimens7.1 MaterialThe material may be in any form. For com-paring results between materials, best results will be obtainedby utilizing the same form and dimensions for each material.7.2 ProductThe product or spec
29、ific part or section of theproduct may be utilized in any desired configuration.NOTE 1For plastics, a 2.0-mm thick sheet of material is often moldedespecially for testing. For example, see the description of sample inPractice D 3182.8. Imaging Conditions8.1 The test shall be performed at appropriate
30、 conditions forthe imaging system, the product or material, and the area of thebody within which the product is intended for use.8.2 Imaging conditions shall be described in the test report.9. ProcedureMethod A9.1 Test Specimen PlacementPlace the test specimen(s) inthe middle of the X-ray imaging ar
31、ea. If a body mimic is used,place the test specimen(s) as appropriate in, on, or under thebody mimic and ensure that the test specimen(s) are in themiddle of the X-ray imaging area. If digital analysis will beused, place the calibration standard within the image so that itdoes not interfere with the
32、 desired imaging of the test speci-men(s) and body mimic.9.2 X-Ray ExposureAs necessary for the imaging system,the product or material, and the area of the body within whichthe product is intended for use.9.2.1 If using film and a body mimic, the exposure shall beof such duration that an optical den
33、sity of 0.8 to 1.2 is obtainedfor the background or through the body mimic, if one is used.9.3 Film Development (If Used)Develop the X-ray film inaccordance with the manufacturers instructions. If a digitalanalysis method will be used, convert the developed film3SRM 1001 has been found suitable for
34、this purpose. The sole source of supplyof the apparatus known to the committee at this time is National Institute ofStandards and Technology (NIST), 100 Bureau Dr., Stop 1070, Gaithersburg, MD20899-1070, https:/srmors.nist.gov. If you are aware of alternative suppliers, pleaseprovide this informatio
35、n to ASTM International Headquarters. Your comments willreceive careful consideration at a meeting of the responsible technical committee,1which you may attend.F640072image(s) to digital format using an appropriate digital scanningor photographic method.9.4 Qualitative AnalysisVisually compare the i
36、mage(s) ofthe test specimen to the background on the film or in the digitalimage (whether original or converted from film).9.5 Quantitative Analysis:9.5.1 Measurement of Optical Density (Film):9.5.1.1 BackgroundMeasure the background or bodymimic optical density with a densitometer to determinewheth
37、er it is within the specified range of 0.8 to 1.2.9.5.1.2 Test Specimen ImageMeasure the optical densityof the image of the test specimen with a densitometer.9.5.1.3 Optical Density DifferenceSubtract the opticaldensity of the test specimen from the optical density of thebackground. If applicable, c
38、ompare this difference to therequired contrast specified in the standard for the medicaldevice.9.5.2 Measurement of Pixel Density (Digital):9.5.2.1 Set Grayscale RangeSet the fully clear portion ofthe imaged calibration standard to level 0 and the fully opaqueportion of the imaged calibration standa
39、rd to 255.9.5.2.2 BackgroundMeasure the background pixel inten-sity.9.5.2.3 Test SpecimenMeasure the pixel intensity of thetest specimen image. Pixel intensity may be measured atmultiple points and averaged or used to determine radiopacityat different points in the test specimen.9.5.2.4 Pixel Intens
40、ity DifferenceSubtract the pixel inten-sity of the test specimen from the pixel intensity of thebackground.10. ProcedureMethod B10.1 Test Specimen PlacementPlace the test specimen(s)in the middle of the X-ray imaging area. If digital analysis willbe used, place the calibration standard within the im
41、age so thatit does not interfere with the desired imaging of the testspecimen(s) and body mimic.10.2 X-Ray ExposureAs necessary for the imaging sys-tem, the product or material, and the area of the body withinwhich the product is intended for use.10.3 Film DevelopmentIf film is used, develop the X-r
42、ayfilm in accordance with the manufacturers instructions. If adigital analysis method will be used, convert the developedfilm image(s) to digital format using an appropriate digitalscanning or photographic method.10.4 Qualitative AnalysisVisually compare the image(s)of the test specimen to the user-
43、defined standard on the film orin the digital image (whether original or converted from film).10.5 Quantitative AnalysisCompare the image(s) of thetest specimen(s) with the user-defined standard(s) in accor-dance with 9.5.11. ProcedureMethod C11.1 Test Specimen PlacementPlace the test specimen(s)and
44、 the user-defined standard as appropriate in, on, or under thebody mimic and ensure that the test specimen(s) and user-defined standard(s) are in the middle of the X-ray imaging area.If digital analysis will be used, place the calibration standardwithin the image so that it does not interfere with t
45、he desiredimaging of the test specimen(s) and body mimic.11.2 X-Ray ExposureAs necessary for the imaging sys-tem, the product or material, and the area of the body withinwhich the product is intended for use.11.3 Film DevelopmentIf film is used, develop the X-rayfilm in accordance with the manufactu
46、rers instructions. If adigital analysis method will be used, convert the developedfilm image(s) to digital format using an appropriate digitalscanning or photographic method.11.4 Qualitative AnalysisVisually compare the image(s)of the test specimen(s) to the user defined standard(s) on thefilm or in
47、 the digital image (whether original or converted fromfilm).11.5 Quantitative AnalysisCompare the image(s) of thetest specimen(s) with the user defined standard(s) in accor-dance with 9.5.12. Report12.1 The report shall include the following:12.1.1 All test equipment, including source type, filter t
48、ype,detector type, machine geometry, machine type and modelnumbers, and film type and resolution (if film is used) orimaging system resolution (if digital analysis is used).12.1.2 All test conditions, including the specific values ofkVp and mAs, the source-to-detector distance, the object-to-detecto
49、r distance, and, if film is used, the focus-film distanceand film exposure settings.12.1.3 If applicable, specification requirements, as listed inthe requirements of the standard specification for the medicaldevice and the number and title of the medical device specifi-cation.12.1.4 Test sample description, including the manufacturername; the type of device or part; the dimensions, includingdiameter, wall thickness, and so forth; and the specific mate-rial(s), including elements or chemical formula(e), and the typeof radiopaqu
