1、Designation: F640 12Standard Test Methods forDetermining Radiopacity for Medical Use1This standard is issued under the fixed designation F640; the number immediately following the designation indicates the year of originaladoption or, in the case of revision, the year of last revision. A number in p
2、arentheses indicates the year of last reapproval. A superscriptepsilon () 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 of
3、materials and products utilizing X-ray basedtechniques, including fluoroscopy, angiography, CT (computedtomography) and DEXA (dual energy X-ray absorptiometry),also known as DXA, The results of these measurements are anindication of the likelihood of locating the product within thehuman body.1.2 Rad
4、iopacity is determined by (a) qualitatively compar-ing image(s) of a test specimen and a user-defined standard,with or without the use of a body mimic, or (b) quantitativelydetermining the specific difference in optical density or pixelintensity between the image of a test specimen and the imageof a
5、 user-defined standard, with or without the use of a bodymimic.1.3 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.4 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is t
6、heresponsibility 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:2B209 Specification for Aluminum and Aluminum-AlloySheet and PlateD3182 Practice for R
7、ubberMaterials, Equipment, and Pro-cedures for Mixing Standard Compounds and PreparingStandard Vulcanized SheetsE94 Guide for Radiographic ExaminationE1316 Terminology for Nondestructive ExaminationsF647 Practice for Evaluating and Specifying ImplantableShunt Assemblies for Neurosurgical Application
8、3. Terminology3.1 DefinitionsFor definitions of terms relating to X-rayprocedures, refer to Terminology E1316.3.2 Descriptions of Terms:3.2.1 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
9、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 ydirections3.2.3 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-bitgraysc
10、ale image3.2.4 optical density, nthe range of values of opticaldensity as measured by a densitometer; in this test method theexpected range 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 di
11、gits to the right of the decimal point.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,reported to within the signifi
12、cance 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 may be one developedby t
13、he user.1These test methods are under the jurisdiction of ASTM Committee F04 onMedical and Surgical Materials and Devices and are the direct responsibility ofSubcommittee F04.15 on Material Test Methods.Current edition approved Dec. 15, 2012. Published January 2013. Originallyapproved in 1979. Last
14、previous edition approved in 2007 as F640 07. DOI:10.1520/F0640-12.2For 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 we
15、bsite.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States14. Summary of Test Methods4.1 The test specimen is placed so it sits at or near themiddle of the X-ray image area i
16、n the X-ray imaging system.X-ray images are made at specified voltages, times, andcurrents that are typical of those used in the X-ray diagnosis ofhumans. Preferred settings are those appropriate for the prod-uct and for the particular area of body interest (for example,leg, heart, and so forth). Th
17、e radiopacity of the test specimenand user-defined standard is evaluated in terms of the imagebackground with or without the use of a body mimic. Theradiopacity may be reported qualitatively or quantitatively.5. Significance and Use5.1 These methods are intended to determine whether amaterial, produ
18、ct, or part of a product has the degree ofradiopacity desired for its application as a medical device in thehuman body. This method allows for comparison with orwithout the use of a body mimic. Comparisons without the useof a body mimic should be used with caution as the relativeradiopacity can be a
19、ffected when imaging through the humanbody.5.2 These methods allow for both qualitative and quantita-tive evaluation in different comparative situations.6. Apparatus6.1 X-Ray Imaging System.6.2 X-Ray Film or Digital Image Acquisition SystemThefilm or digital imaging system shall be appropriate for t
20、heimaging conditions used. A grid may be used.6.3 Body Mimic (if used): (Note that this is not an all-inclusive list and other body mimics might be appropriate.)6.3.1 AnimalAn appropriate animal, or portion of appro-priate animal, with which to perform the tests may be used.6.3.2 CadaverA human body
21、, or portion of human body,with which to perform the tests may be used.6.3.3 Metal, Plastic, or CompositeA metal, plastic, orcomposite material of appropriate dimensions may be used.For example, a 10.0 mm or 15.0 6 0.15 mm thick aluminumsheet might be appropriate. The aluminum sheet shall be99 % in
22、purity, or type 1100 or purer, in accordance withSpecification B209.6.3.4 PhantomAn apparatus that mimics a portion of thebody may be used; Note that this apparatus may be as complexas a manufactured torso with appropriate densities representingall portions of the anatomy within the torso, or may be
23、 assimple defined thickness of water.6.3.5 Step WedgeA step wedge may be used as a user-defined standard, if it has the requisite thickness steps.6.4 Rubber BlanketsBlankets incorporating X-ray absorb-ers may be used to mask the image area not covered by thebody mimic material (this prevents undercu
24、tting). Lead sheetsmay also 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 Densitometer (if used)The densitometer shall be ca-pable of measuring the optical density over the range of 0.0 to3.0 optical density uni
25、ts, minimum. It shall have a measuringaccuracy 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 anal
26、ysis is used.6.7 Step Tablet, for 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 materia
27、l.7.2 ProductThe product or specific 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 D3182.8. Imaging Conditions8.1 The test sh
28、all be performed at appropriate conditions forthe imaging system, the product or material, and the area of thebody within which the product is intended for use. Forexample, each X-ray image is made at a specified voltage,current, time contrast and brightness, that are typical of thoseused in the X-r
29、ay diagnosis of humans. Preferred settings arethose appropriate for the product and for the particular area ofbody interest (for example, leg, heart, and so forth).8.2 Imaging conditions shall be described in the test report.9. Procedure9.1 Test Specimen PlacementPlace the test specimen(s)and the us
30、er-defined standard at or near the middle of the X-rayimaging area. If a body mimic is used, place the test speci-men(s) and the user-defined standard as appropriate in, on, orunder the body mimic. As appropriate, the effect of the clinicalX-ray table shall also be included with use of an appropriat
31、ematerial of thickness similar to that used clinically.9.2 X-Ray ExposureComplete X-ray exposure using con-ditions typical of those used in the X-ray diagnosis of humans,the product, and for the particular area of interest.9.2.1 If using film, the exposure shall be of such durationthat an optical de
32、nsity of 0.8 to 1.2 is obtained for thebackground.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 filmimage(s) to digital format using an appropriate digital scanningor photographic
33、 method.9.4 Qualitative AnalysisVisually compare the image(s) ofthe test specimen and the user-defined standard to the back-ground on the film or in the digital image (whether original orconverted from film).9.5 Quantitative Analysis:9.5.1 Measurement of Optical Density (Film):F640 1229.5.1.1 Backgr
34、oundMeasure the background (includesbody mimic, if used) optical density with a densitometer todetermine whether 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 and the user-defined standardwith a densitometer.9.5
35、.1.3 Optical Density DifferenceSubtract the opticaldensity of the test specimen and the user-defined standard fromthe optical density of the background.9.5.2 Measurement of Pixel Density (Digital):9.5.2.1 BackgroundMeasure the background pixel inten-sity.9.5.2.2 Test SpecimenMeasure the pixel intens
36、ity of thetest specimen and user-defined standard. Pixel intensity may bemeasured at multiple points and averaged or used to determineradiopacity at different points in the test specimen.9.5.2.3 Pixel Intensity DifferenceSubtract the pixel inten-sity of the test specimen and the user-defined standar
37、d from thepixel intensity of the background.10. Report10.1 The report shall include the following:10.1.1 All test equipment, including source type, filter type,detector type, machine geometry, machine type and modelnumbers, and film type and resolution (if film is used) orimaging system resolution (
38、if digital analysis is used).10.1.2 All test conditions, including the specific values ofkVp and mAs, the source-to-detector distance, the object-to-detector distance, and, if film is used, the focus-film distanceand film exposure settings.10.1.3 If applicable, specification requirements, as listed
39、inthe requirements of the standard specification for the medicaldevice and the number and title of the medical device specifi-cation (for example, Practice F647).10.1.4 Test specimen description, including the manufactur-ers name; the type of device or part; the dimensions, includingdiameter, wall t
40、hickness, and so forth; and the specificmaterial(s), including elements or chemical formula(e), and thetype of radiopaque additive (if any) and how it occurs in thepart, such as a uniform dispersion, line of specific crosssection, and so forth.10.1.5 Body mimic description, if used : (1) for a phant
41、om,include the manufacturers name and model number, and thetype of device, for example, “torso” or “knee,” if applicable.Also include a description of the materials and dimensions. (2)for a cadaver, include the location and dimensions; (3) for ananimal, include the location and dimensions.10.1.6 If
42、used, the material and thickness representing theX-ray table.10.1.7 User-defined standard description, including materi-als and dimensions.10.1.8 If applicable, test specimen and user-defined stan-dard placement in comparison to the body mimic (that is, ontop of, within, underneath, near, and so for
43、th).10.1.9 Optical and X-ray image(s) of the test specimen(s).10.1.10 Optical density or pixel intensity readings for allmeasurements as described in 9.5.11. Precision and Bias11.1 The precision and bias of these test methods have notyet been established.11.2 It is intended to develop data for the o
44、verall methodand the measurement of density from a round-robin test.12. Keywords12.1 implants; radiopacity; surgical applications; surgicaldevices; surgical implants; test methods; X-rayAPPENDIX(Nonmandatory Information)X1. RATIONALEX1.1 GeneralThe initial development of this standard wasbased on th
45、e need to determine the location in the body ofplastic parts of small diameter. This led to a proposed require-ment for an optical density contrast measured on the medicaldevice. However, radiopacity is a property of many types ofmedical devices and its required numerical level is influencedby many
46、variables, some of the principal being: type ofmaterial, size, thickness, and configuration; part of body orcirculatory system; and X-ray energy applied during theprocedure.X1.2 Specification ValuesThis standard does not have anyrequirements for minimum levels of radiopacity, nor is there apreferred
47、 test method (of the three described). The standardspecification for the medical devices may specify materials andvalues for some parameters of the test method, such as for thebody mimic and the X-ray test voltageX1.3 Background DensityIt has been proposed that, formany applications, an optical dens
48、ity contrast of 0.10 issatisfactory. For larger pieces and thin sections of the humanbody, a contrast of 0.05 optical density units may be adequate.F640 123SUMMARY OF CHANGESCommittee F04 has identified the location of selected changes to this standard since the last issue (F640 07)that may impact t
49、he use of this standard. (Approved Dec. 15, 2012.)(1) Method A was removed and methods B and C werecombined.(2) The location of the test specimen in the X-ray image wasmodified to allow it to sit at or near the middle versus only themiddle.(3) The following was added to the procedure: As appropriate,the effect of the clinical X-ray table shall also be included withuse of an appropriate material of thickness similar to that usedclinically.(4) The calibration standard for the digital analysis (standardthat creates a clear and completely op
