ASTM E1815-2006 Standard Test Method for Classification of Film Systems for Industrial Radiography《工业用射线照相胶片系统分类的标准试验方法》.pdf

1、Designation: E 1815 06Standard Test Method forClassification of Film Systems for Industrial Radiography1This standard is issued under the fixed designation E 1815; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last re

2、vision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers a procedure for determinationof the performance of film systems used for industrial radiog-raphy. Th

3、is test method establishes minimum requirements thatcorrespond to system classes.1.2 This test method is to be used only for direct exposure-type film exposed with lead intensifying screens. The perfor-mance of films exposed with fluorescent (light-emitting) inten-sifying screens cannot be determine

4、d accurately by this testmethod.1.3 The values stated in SI units are to be regarded asstandard. The values given in brackets are for information only.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

5、 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:2E94 Guide for Radiographic ExaminationE 999 Guide for Controlling the Quality of Industrial Ra-diographic Film Processing

6、E 1079 Practice for Calibration of Transmission Densitom-etersE 1316 Terminology for Nondestructive Examinations2.2 ANSI Standards:3PH 2.40 Root Mean Square (rms) Granularity of Film(Images on One Side Only) Method of Measuring2.3 ISO Standards:3ISO 5-2 Photography Density MeasurementsPart 2: Geo-me

7、tric Conditions for Transmission DensityISO 5-3 Photography Density MeasurementsPart 3:Spectral ConditionsISO 7004 PhotographyIndustrial Radiographic Film, De-termination of ISO Speed and Average Gradient WhenExposed to X and Gamma Radiation2.4 DIN Standard:3EN 584-1 Non-Destructive TestingIndustria

8、l Radio-graphic FilmClassification of Film Systems3. Terminology3.1 DefinitionsFor definitions of terms used in this testmethod, refer to Terminology E 1316.3.2 Definitions of Terms Specific to This Standard:3.2.1 film systemthe film and associated film-processingrequirements in accordance with the

9、criteria established by themanufacturers of the film and processing chemicals.3.2.2 gradient Gthe slope of the characteristic curve at acertain density, D, and a measure of the contrast of the filmsystem.3.2.3 granularity, sDnonuniformity of density in a radio-graphic image typically caused by rando

10、m, statistical group-ings of individual silver particles in processed film.3.2.4 ISO speed Sdetermined by the dose Ks, measured ingray at a specified optical density, D, in the radiograph.4. Significance and Use4.1 This test method provides a relative means for classifi-cation of film systems used f

11、or industrial radiography. The filmsystem consists of the film and associated processing system(the type of processing and processing chemistry). Section 6describes specific parameters used for this test method. Ingeneral, the classification for hard X-rays, as described inSection 6, can be transfer

12、red to other radiation energies andmetallic screen types, as well as screens without films. Theusage of film system parameters outside the energy rangesspecified may result in changes to a film/system performanceclassification.1This test method is under the jurisdiction of ASTM Committee E07 onNonde

13、structive Testing and is the direct responsibility of Subcommittee E07.01 onRadiology (X and Gamma) Method.Current edition approved Feb. 1, 2006. Published February 2006. Originallyapproved in 1996. Last previous edition approved in 2001 as E 1815 - 96 (2001).2For referenced ASTM standards, visit th

14、e 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

15、10036.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.4.1.1 The film performance is described by signal and noiseparameters. The signal is represented by gradient and the noiseby granularity.4.1.2 A film is assigned a particular clas

16、s if it meets all fourof the minimum performance parameters: for Gradient G atD = 2.0 and D = 4.0, granularity sDat D = 2.0, and gradient/noise ratio at D = 2.0.4.2 This test method describes how the parameters shall bemeasured and demonstrates how a classification table can beconstructed.4.3 Manufa

17、cturers of industrial radiographic film systemswill be the users of this test method. The result is a classifica-tion table as shown by the example given in Table 1. This tablealso includes speed data for user information. Users of indus-trial radiographic film systems may also perform the tests and

18、measurements outlined in this test method, provided that therequired test equipment is used and the methodology isfollowed strictly.4.4 The publication of classes for industrial radiographyfilm systems will enable specifying bodies and contractingparties to agree to particular system classes, which

19、are capableof providing known image qualities. See 7.2.4.5 European standard EN 584-1 describes a similar methodfor classification of film systems for industrial radiography, butits class definitions and number of classes do not align exactlywith this test method. International users of these standa

20、rdsshould be aware of these differences for their particularapplications.NOTE 1ASTM research report E071005 contains documentation oftechnical methods used during the development of this test method.45. Sampling and Storage5.1 For determination of the gradient and granularity of afilm system, it is

21、important that the samples evaluated yield theaverage results obtained by users. This will require evaluatingseveral different batches periodically, under the conditionsspecified in this test method. Prior to evaluation, the samplesshall be stored in accordance with the manufacturers recom-mendation

22、s for a length of time to simulate the average age atwhich the product is normally used. Several independentevaluations shall be made to ensure the proper calibration ofequipment and processes. The basic objective in selecting andstoring samples as described above is to ensure that the filmcharacter

23、istics are representative of those obtained by a con-sumer at the time of use.6. Procedure6.1 Principle:6.1.1 Film to be tested shall be exposed to X-rays fromtungsten target tubes. Inherent filtration of the tube, plus anadditional copper filter located as close to the target as possible,shall prov

24、ide filtration equivalent to 8.00 6 0.2 mm of copper.6.1.2 The film system includes a front and a back screen of0.02 to 0.25-mm lead. If single-coated films are used, theemulsion-coated surface must face the X-ray tube. Vacuum orpressure cassettes may be used to ensure sufficient contactbetween the

25、film and screen.6.2 X-ray Spectral Quality:6.2.1 Use the same X-ray spectral quality for determiningboth the film gradient and its root mean square granularity.Make the film exposures with an 8-mm 0.32-in. copper filterat the X-ray tube and the kilovoltage set such that thehalf-value layer in copper

26、 is 3.5 mm 0.14 in. The kilovoltagesetting will be approximately 220 kV.6.2.2 Determine the required kilovoltage setting by makingan exposure (or exposure rate) measurement with the detectorplaced at a distance of at least 750 mm 29.5 in. from the tubetarget and with an 8-mm 0.32-in. copper filter a

27、t the tube.Then make a second measurement with a total of 11.5 mm0.45 in. of copper at the tube. These filters should be made of99.9 % pure copper.6.2.3 Calculate the ratio of the first and second readings. Ifthis ratio is not 2, adjust the kilovoltage up or down and repeatthe measurements until a r

28、atio of 2 (within 5 %) is obtained.Record the machine setting of the kilovoltage for use with thefilm tests.6.3 Film Cassette and Screens:4Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR: E071005.TABLE 1 Typical Film System Class

29、ificationAutomatic Film ProcessingDeveloper: Type ADeveloper immersion time: XXX secondsDeveloper temperature: XXC/YYFFilm TypeAASTM SystemClassMinimum Gradient G atMinimumGradient/GranularityRatio, G/sD,atD = 2.0 aboveDoMaximumGranularity, sD,at D = 2.0 aboveDoISO SpeedSDose, Ks,mGy,D =2.0D =2.0abo

30、ve DoD =4.0above DoA Special 5.4 9.1 360 0.015 32 29.0B I 4.5 8.4 281 0.016 64 14.0C I 4.4 7.6 232 0.019 100 8.7D I 4.4 7.6 169 0.026 200 4.6E II 4.4 7.6 142 0.031 320 3.2F III 4.0 5.2 114 0.035 400 2.5G W-A 4.2 6.5 225 0.019 100 8.6H W-B 4.1 5.3 170 0.025 300 5.0AFamily of films ranging in speed an

31、d image quality.E18150626.3.1 The film cassette (holder) shall provide a means ofensuring good film screen contact. A vacuum cassette may beused.6.3.2 Lead-foil screens shall be used with the front-screenthickness being 0.130 6 0.013 mm 0.005 6 0.05 in. and theback-screen thickness being 0.250 6 0.0

32、25 mm 0.010 60.001 in.NOTE 2These thicknesses reflect commercially available tolerancesin lead foil for use as radiographic screens.6.3.3 It is especially important that the exposure to the filmspecimen for the granularity measurements be spatially uni-form. Any nonuniformities in X-ray transmission

33、 of the cas-sette front or nonuniformities or defects in the lead-foil screenscould influence the granularity measurement. Therefore, exer-cise considerable care in selection and maintenance of thecassette and lead screens to minimize these effects.6.3.4 Expose single-coated films with the emulsion-

34、coatedsurface in contact with the front screen.6.4 Film ProcessingThe film image quality will vary withthe processing variables, such as chemistry, temperature, andmethod of processing (manual or automatic). The film process-ing and record requirements shall be in accordance with GuideE 999.6.5 Expo

35、sure Conditions:6.5.1 The plane of the film shall be normal to the central rayof the X-ray beam. Use a diaphragm at the tube to limit thefield of radiation to the film area. The X-ray tube target to filmdistance shall be adequate to ensure that the exposure over theuseful area of each exposure step

36、is uniform to within 3 %.6.5.2 To minimize the effects of backscattered radiation, usea 6.3 6 0.8-mm 14 6132-in. thick lead shielding behind thecassette. The shielding lead shall extend at least 25 mm 1 in.beyond each edge of the cassette. Alternatively, the shieldinglead may be omitted, provided th

37、at the cassette is supportedsuch that the X-ray beam strikes no scattering material, otherthan air, for a distance of at least 2 m 78.7 in. behind thecassette.6.5.3 Modulation of the X-ray exposure may be accom-plished by changing the exposure time or tube target to filmdistance. Changing the tube c

38、urrent is not recommended butmay be done, provided it is verified by measurement (see 6.2)that the X-ray spectral quality does not change.6.5.4 Measure exposures with an air-ionization chamber, orother types of X-ray detectors, having linear response over therange of X-ray intensities and exposure t

39、imes used for the filmexposures.6.5.5 During and after exposure, prior to processing, keepthe film at a temperature of 23 6 5C 59.7 6 5F and arelative humidity of 50 6 20 %. Start processing of the filmbetween 30 min and 8 h after exposure. Process an unexposedspecimen of the film sample with the X-

40、ray-exposed specimenin order to determine the base plus fog density.6.5.6 Measure the visual diffuse transmission density of theprocessed films with a densitometer complying with therequirements of ISO 5-2 and calibrated by the method ofPractice E 1079. Use a minimum aperture of 7 mm 0.275 in.6.6 Me

41、asurement of Gradient G:6.6.1 Gradient G relates to a D versus log K curve. In thescope of this test method, G is calculated from the slope of a Dversus K curve at density (DDo), as follows:G 5dDd log K5Klog e3dDdK(1)where:K = dose required for density D Do, andDo= fog and base density.6.6.2 The D v

42、ersus K curve is approximated by a polyno-mial of the third order. To obtain a regular and reliable shapeof this curve, make a series of exposures to obtain at least 12uniformly distributed measuring points between density 1.0and 5.0 above Do.6.6.3 Average the Gradient G measurements, with a maxi-mu

43、m inaccuracy of 65%.6.7 Root Mean Square (rms) Granularity, sD:6.7.1 Determine the rms granularity of the film in accor-dance with ANSI PH 2.40, with the following exceptions:6.7.2 The procedure is limited to the measurement ofcontinuous tone black-and-white industrial X-ray films viewedby transmitt

44、ed light. The film may have emulsion coated onone side or both sides of the film support.6.7.3 Expose the film specimen with X-rays having thespectral quality described in 6.2. The cassette and lead-foilscreens shall be as specified in 6.3. Expose the film specimenin accordance with the exposure con

45、ditions of 6.5. Exercisecare to ensure that the film specimen does not contain densityvariations arising from the exposing equipment (such asnonuniform beam filters or damaged or defective lead screens).During and after exposure, prior to processing, maintain thefilm specimen at the temperature and

46、relative humidity condi-tions specified in 6.5.5. The film processing chemicals andprocedures shall be the same as those used for determininggradient, and they shall be described completely as specified in6.4.6.7.4 The film specimen for granularity measurement shallhave a diffuse density of 2.00 6 0

47、.05 above base plus fog. Asan alternative, three or more samples of the film specimen atdifferent density levels, within the range from 1.80 to 2.20,may be measured, and the granularity value at a diffuse densityof 2.00, above base plus fog, shall be taken from a smoothcurve drawn through a plot of

48、the data points. The granularityvalue shall be in terms of diffuse density.6.7.4.1 The microdensitometer scanner output is measuredas projection density. Thus to obtain the desired diffuse density,convert the data using the slope of the curve of diffuse densityversus projection density at the mean d

49、ensity value of thegranularity film specimen. Determine this curve using a filmhaving a stepped series of densities, which is prepared usingthe same type film, exposure, and processing techniques asused for the granularity film specimen. Measure the diffusedensity of each step with a microdensitometer. The specimenfilm shall be scanned using identical microdensitometer set-tings. A limited range of densities can typically be measuredfor a given microdensitometer gain setting. The stepped seriesof densities shall lie within that range.