ASTM E746-2002 Standard Test Method for Determining Relative Image Quality Response of Industrial Radiographic Film《工业用X射线照相胶片的相关图像质量特性曲线测定的标准试验方法》.pdf

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1、Designation: E 746 02Standard Test Method forDetermining Relative Image Quality Response of IndustrialRadiographic Film Systems1This standard is issued under the fixed designation E 746; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revisi

2、on, the year of last revision. 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 the determination of the relativeimage quality response of industrial radiogr

3、aphic film systemswhen exposed to 200-kV X-rays. The evaluation of the film isbased upon the threshold visibility of penetrameter holes in aspecial image quality indicator (IQI). Results for a given filmtype may vary, depending upon the particular developmentsystem used. It is, therefore, necessary

4、to state the developmentsystem and geometric conditions used in this determination. Byholding the technique parameters (except exposure time) andprocessing parameters constant, the image quality response ofradiographic film may be evaluated on a relative basis.1.2 Alternately, this test method may b

5、e used for determi-nation of the relative image quality response of a radiographicfilm system when exposed to 200-KV X-rays as any othersingle component of the system (such as screens) is varied.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use.

6、 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:B 152 Specification for Copper Sheet, Strip, Plate, andRolled Bar2E 999 Guide

7、for Controlling the Quality of IndustrialRadiographic Film3E 1025 Practice for Design, Manufacture, and MaterialGrouping Classification of Hole-Type Image Quality Indi-cators IQI Used for Radiology3E 1079 Practice for Calibration of Transmission Densitom-eters3E 1316 Terminology for Nondestructive E

8、xaminations3E 1815 Test Method for Classification of Film Systems forIndustrial Radiography32.2 ANSI Standard4:ANSI PH2.19 Photography Density Measurements-Part 2:Geometric Conditions for Transmission Density2.3 ISO Standards4:ISO 5-2 Photography Density Measurements-Part 2: Geo-metric Conditions fo

9、r Transmission DensityISO 7004 Photography- Industrial Radiographic Film, De-termination of ISO Speed and Average Gradient WhenExposed to X and Gamma Radiation3. Terminology3.1 DefinitionsFor definitions of terms used in this testmethod, refer to Terminology E 1316.4. Significance and Use4.1 This te

10、st method provides a relative means for deter-mining the image quality performance response for a givenfilm chemistry system used for industrial radiography. It is onlyto be used for relative comparisons. It is not intended to qualifyperformance of a film chemistry system to detect specificdiscontin

11、uities in a product or specimen undergoing X-rayexamination.4.2 Film chemistry image quality performance is describedby EPS, Equivalent Penetrameter Sensitivity. For a detaileddescription of EPS, see Practice E 1025.4.3 It is not the intent of this standard to specify perfor-mance requirements of th

12、e film chemistry system. Test MethodE 1815 can be used to specify performance requirements at 200kV. This test method was used, and can be used to corroborateTest Method E 1815 results at 200 kV. This test method is asubjective means of determining film chemistry image qualityperformance, whereas Te

13、st Method E 1815 uses instrumentmeasurements to calculate performance and is therefore anobjective test method.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 e

14、dition approved January 10, 2002. Published March 2002. Originallypublished as E 746 80. Last previous edition E 746 93 (1998).2Annual Book of ASTM Standards, Vol 02.01.3Annual Book of ASTM Standards, Vol 03.03.4Available from American National Standards Institute, 25 W. 43rd St., 4thFloor, New York

15、, NY 10036.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.4.4 This test method could be used to evaluate relative filmchemistry system image quality performance at Net Density4.0 where some instrument measurements are currently notf

16、easible.5. Test Specimen5.1 The test specimen shall consist of a special imagequality indicator (IQI) placed on the tube side of a 36mm(138-in.) plastic plate for 30kV, and a 19mm (34 in.) steelplate for 200kV.5.1.1 The special image quality indicator (IQI) shall befabricated from Lucite plastic for

17、 30kV, and mild steel for200kV. The dimensions shall conform to Fig. 1. The IQI stepsmay be fabricated separately and taped together to form thepenetrameter array as shown. The tape shall not cover any ofthe holes in the IQI.5.1.2 The absorber plate shall be made of Lucite plastic for30kV, and mild

18、steel for 200kV. Both shall be at least 200 by250 mm (8 by 10 in.) wide and long. The steel plate shall be 196 0.12 mm (0.750 6 0.005 in.) thick. Thickness of the plasticplate shall be 36 6 0.12 mm (138 6 0.005 in.). The surfacefinish of both absorber plates shall be a maximum of 6.3 m(250 in.) Ra,

19、ground finish (both faces).6. Calibration of X-Ray Source6.1 Use a target to detector distance at least 750 mm (29.5in.) for all exposures.6.2 The voltage calibration of the X-ray source for 30kV isbased on ISO 7004 method for 100kV calibration, modifiedfor 30kV. With a 7.62-mm (0.30-in.) aluminum f

20、ilter at theX-ray tube port, adjust the kilovoltage until the half value layerin aluminum is 1.52 mm (0.06 in.). That is, the intensity of theX-ray beam with 9.14mm (0.36in.) aluminum at the tubeport shall be one-half that with 7.62mm (0.30in.) aluminumat the tube port. Exposures shall be made using

21、 the voltage thusdetermined and with 7.62 mm (0.30 in.) of aluminum at thetube port. No lead screen shall be used.6.3 The voltage calibration of the X-ray source for 200kVis based on ISO 7004. With an 8mm (0.32in.) copper filter atthe X-ray tube adjust the kilovoltage until the half value layerin co

22、pper is 3.5 mm (0.14 in.) (see Specification B 152). MakeStep Identification Shim Thickness, mm (in.) Hole Identification Hole Size, mm (in.)15 0.38 6 0.012 (0.015 6 0.0005) 32 0.81 6 0.025 (0.0326 0.001)10 0.25 6 0.012 (0.010 6 0.0005) 31 0.79 6 0.025 (0.031 6 0.001)8 0.20 6 0.012 (0.008 6 0.0005)

23、28 0.71 6 0.025 (0.0286 0.001)5 0.13 6 0.012 (0.005 6 0.0005) 25 0.64 6 0.025 (0.025 6 0.001)23 0.58 6 0.025 (0.0236 0.001)20 0.50 6 0.025 (0.020 6 0.001)Hole Spacing (horizontal): 5 6 0.1 mm (0.2 6 0.004 in.) NonaccumulativeRow Spacing: 3 6 0.1 mm (0.2 6 0.004 in.)Spacing between hole sets: 5 6 0.1

24、 mm (0.2 6 0.004 in.)All other dimensions shall be in accordance with standard engineering practice.FIG. 1 Image Quality IndicatorE746022a reading of the detector with 8 mm (0.32 in.) of copper at thetube, and then, make a second reading with a total of 11.5 mm(0.45 in.) at the tube.6.4 For both 200

25、kV and 30kV X-ray beam calibrationmethods. Calculate the ratio of the two readings. If this ratio isnot 2, adjust the kilovoltage up or down and repeat themeasurement until a ratio of 2 (within 5 %) is obtained. Recordthe machine settings and use for the film tests. During tests,remove all of the fi

26、lters for both 200kV and 30kV methods.7. Density Measurements7.1 Measure the visual diffuse transmission density of theprocessed films with a densitometer complying with therequirements of ANSI PH2.19 and ISO 52 and calibrated bythe method of Practice E 1079. Use a minimum aperture of 7mm (0.275 in.

27、).8. Film Holder and Screens8.1 Enclose a single film in a cassette with low absorption.When using the 30kV method, and after the X-ray beam hasbeen calibrated for 30kV, a film holder absorption factor shallbe determined. With the 7.62mm (0.3in.) aluminum filter atthe X-ray tube make an exposure wit

28、h film in the film holder.Films exposed to X-ray without a holder will need to behandled in lighting conditions that are appropriate (safe light).Determine an exposure that produces 2.00 6 15 % film densityon the film exposed in the film holder. Use the densitometer inaccordance with Section 6. Use

29、the same exposure on the filmexposed outside the film holder. Subtract the film density fromthe film exposed in a holder from the film density of the filmexposed outside the film holder. The difference shall not exceed2%. The cassette shall provide a means for ensuring goodfilm-screen contact.8.2 Fo

30、r the 200kV method. Place the film between lead-foil screens, the front screen being 0.130 6 0.013 mm (0.0056 0.0005 in.) thick and the back screen 0.250 6 0.025 mm(0.010 6 0.001 in.) thick.NOTE 1These thicknesses reflect commercially available tolerancesin lead foil for use as radiographic screens.

31、8.3 When the component to be evaluated is a screen orscreen system, other than lead screen as specified in 8.2, placethe film in the proper position with the screen or screen system.8.4 Use a 6.3 6 0.8 mm (14 6132 in.) thick lead “backup”behind the cassette. The backup lead shall extend at least 25m

32、m (1 in.) beyond each edge of the cassette.9. Procedure9.1 The source to film distance is based upon achieving ageometrical unsharpness (Ug) of 0.05 mm (0.002 in.) or less ona36mm(138 in.) thick plastic plate for 30kV and a 19 mm(34 in.) thick absorber plate for 200kV. Calculate the mini-mum source

33、to film distance, D, in millimetres, as follows:D 5 381 fwhere:D = source to film distance, mm, andf = focal spot size, mm.The distance shall be not less than 1 m (39.4 in.).9.2 See the physical set up as shown in Fig. 2. Position theX-ray tube directly over the center of the test specimen andfilm.

34、The plane of the film and test specimen must be normalto the central ray of the X-ray beam. Use a diaphragm at thetube to limit the field of radiation to the film area.9.3 Exposure:9.3.1 Expose the film at the kV setting as determined inSection 6. Remove all filters at the tube before the exposure.A

35、djust the exposure time to give a film density of 2.00 6 15 %FIG. 2 Setup for Energy Calibration and ExposuresE746023in the center of the film as measured with a densitometer. Usethe densitometer in accordance with Section 7.9.3.2 Make three separate exposures using the same filmcassette each time.9

36、.3.3 Identify the film number, type, exposure, and othertechnique data by means of lead letters, or numerals, placed inthe upper righthand corner of the steel plate(s). Do not place soas to interfere with the image of the holes in the IQI. Makethese identification symbols as small and unobtrusive as

37、possible. Record this identification number on the data sheetfor this exposure (see Section 10).9.3.4 In order to minimize any effects caused by latentimage instability, process the exposed film not more than 8 hafter exposure.9.4 Film ProcessingThe image quality response of thefilm may vary with th

38、e processing variables such as chemistry,temperature, and method of processing (manual or automatic).The solutions must be fresh and properly seasoned (see 9.4.1and 9.4.2). The film processing and record requirements shallbe in accordance with Guide E 999.9.4.1 Automatic ProcessingUse industrial X-r

39、ay process-ing solutions in the tests. Keep a record of:9.4.1.1 The brand name of the processor.9.4.1.2 The length of time (61 s) that the film is in thedeveloper, that is, leading edge in to leading edge out.9.4.1.3 The brand name of the developer, including the“starter,” the temperature measured t

40、o within 0.5C (0.9F),and the rate of replenishment to within 65%.9.4.1.4 The brand name and total quantity of film used inseasoning fresh developer solution before processing test films.Process a minimum of ten films (360 by 430-mm (14 by17-in.) per gallon of developer; expose half of each sheet to

41、amaximum density by white light. An acceptable alternative toexposing half of each film sheet is to flash alternate film sheetsfully in equal numbers.9.4.2 Manual ProcessingUse industrial X-ray film pro-cessing solutions in the tests. Keep a record on the data sheetof:9.4.2.1 The time of development

42、 (62 s).9.4.2.2 The temperature of developer measured within0.5C (0.9F).9.4.2.3 The brand name and the total quantity of film used inseasoning the fresh developer solution before processing testfilms. Process a minimum of four 360 by 430-mm (14 by17-in.) sheets of film per gallon of developer soluti

43、on; exposehalf of each sheet of film to maximum density by white lightbefore processing or use alternative method (see 9.4.1.4).10. Data Collection and Evaluation10.1 The three test films for any one film type shall be readindependently by three readers. Each reader shall record thenumber of holes o

44、f a given size visible on each step of the IQI.The viewing box should be masked to prevent stray light fromdistracting the reader, and the room should be darkened withminimal background lighting. A magnifier up to 33 is permit-ted. A sample data sheet is shown in Fig. 3.10.2 Data EvaluationThe data

45、is evaluated by calculatingthe sum of the number of holes of a given size visible on eachstep. The sum is based upon three readers and three radio-graphs. Convert the step/hole size to equivalent penetrametersensitivity (EPS) as follows:EPS, % 5100X3Th2where:h = hole diameter, mm,T = step thickness

46、of IQI, mm, andX = thickness of test object, mm.The number of detectable holes versus the equivalent penet-rameter sensitivity is plotted for each step of the IQI and foreach film type as shown in Fig. 4. The image quality responseis determined for the point where 50 % of the holes are visible.This

47、value is the classification index for the film under test.10.2.1 Alternate-One Method for Data EvaluationIn ad-dition to the curve plotting method described in 10.2, theclassification index may be calculated mathematically betweentwo adjacent 30 hole rows by interpolating between the EPSvalues of th

48、e row with more than 15 visible holes and the rowwith less than 15 visible holes by use of the formula:C 5 Qb115 2 Nb!Qa2 Qb!Na2 Nbwhere:C = the classification index (the midpoints or 50 % point)on the graph (Fig. 4).Na= the total number of visible holes in the row immedi-ately above the midpoint an

49、d Qais the correspondingEPS value.Nb= the total number of visible holes in the row immedi-ately below the midpoint and Qbis the correspondingEPS value.The following example is given for illustrationA row having23 visible holes has an EPS value of 1.57. An adjacent row has12 visible holes and an EPS value of 1.49.C 5 1.49 115 2 12!1.57 2 1.49!23 2 12C 5 1.5110.2.2 Alternate-Two Method for Data EvaluationIn ad-dition to the curve plotting method described in 10.2, the datamay be evaluated by averaging the number of holes of a g