DIN ISO 9236-1-2007 Photography - Sensitometry of screen film systems for medical radiography - Part 1 Determination of sensitometric curve shape speed and average gradient (ISO 92.pdf

1、August 2007DEUTSCHE NORM English price group 14No part of this standard may be reproduced without prior permission ofDIN Deutsches Institut fr Normung e. V., Berlin. Beuth Verlag GmbH, 10772 Berlin, Germany,has the exclusive right of sale for German Standards (DIN-Normen).ICS 37.040.25!,z=O“9872644w

2、ww.din.deDDIN ISO 9236-1Photography Sensitometry of screen/film systems for medical radiography Part 1: Determination of sensitometric curve shape, speed and averagegradient (ISO 9236-1:2004)English version of DIN ISO 9236-1:2007-08Fotografie Sensitometrie an Film-Folien-Systemen fr die medizinische

3、 Radiographie Teil 1: Ermittlung des Verlaufs der sensitometrischen Kurve, der Empfindlichkeit und desmittleren Gradienten (ISO 9236-1:2004)Englische Fassung DIN ISO 9236-1:2007-08SupersedesDIN 6867-1:1997-02www.beuth.deDocument comprises 26 pages10.07DIN ISO 9236-1:2007-08 2 Contents Page National

4、foreword .4 National Annex NA (informative) Bibliography 5 Introduction .6 1 Scope 7 2 Normative references 7 3 Terms and definitions .7 4 General requirements8 4.1 Storage and handling conditions.8 4.2 Safelights8 4.3 X-ray equipment.9 4.4 Air kerma meter9 4.5 Processing9 4.6 Densitometry10 5 Deter

5、mination of sensitometric curve shape10 5.1 General10 5.2 Beam qualities11 5.3 Geometry for curve shape determination .11 5.4 Exposure.14 5.5 Evaluation.14 6 Determination of average gradient 14 7 Determination of speed.16 7.1 Definition 16 7.2 Beam qualities16 7.2.1 General16 7.2.2 Phantom for Tech

6、nique I.16 7.2.3 Phantom for Technique II16 7.2.4 Phantom for Technique III.17 7.2.5 Phantom for Technique IV 17 7.2.6 Establishment of X-ray tube voltage17 7.3 Geometry 19 7.4 Exposure.19 7.5 Evaluation.19 8 Speed and average gradient determination without sensitometric curve.22 9 Uncertainty .22 1

7、0 Test report 23 Annex A (informative) Rationale 24 A.1 Sensitometric curve shape .24 A.2 Speed 24 A.3 Phantoms24 A.4 Air kerma 25 A.5 Dependence of speed on beam quality .25 Bibliography 26 DIN ISO 9236-1:2007-08 3 Figures Figure 1 Geometric set-up of the inverse-square-law sensitometer for exposur

8、e of the screen/film combination .12 Figure 2 Geometric set-up for calibration of the inverse-square-law sensitometer.13 Figure 3 Sensitometric curve .15 Figure 4 Phantom for Technique I .17 Figure 5 Geometric set-up for adjustment of beam qualities used for techniques I, II, III and IV18 Figure 6 G

9、eometric set-up for the measurement of speed (Techniques I, II and III) 20 Figure 7 Geometric set-up for the measurement of speed (Technique IV).21 Tables Table 1 Beam qualities for the determination of the sensitometric curve shape.11 Table 2 Specification of techniques .16 DIN ISO 9236-1:2007-08 4

10、 National foreword This standard has been prepared by Technical Committee ISO/TC 42 “Photography”. The responsible German body involved in its preparation was the Normenausschuss Bild und Film (Cinematography and Photography Standards Committee), Technical Committee NBF NA 049-00-01 AA Strahlungsemp

11、findliche Materialien, Sensitometrie und Formate. The responsible body involved in the preparation of the German-language version was the Normenausschuss Radiologie (Radiology Standards Committee), Technical Committee NAR AA 6/GA 6 Bildgebende Systeme. ISO 9236 consists of the following parts, under

12、 the general title Photography Sensitometry of screen/film systems for medical radiography: Part 1: Determination of sensitometric curve shape, speed and average gradient Part 3: Determination of sensitometric curve shape, speed and average gradient for mammography The following part is under prepar

13、ation: Part 2: Method for determining modulation transfer function (MTF) The DIN Standards corresponding to the International Standards referred to in clause 2 of the ISO Standard are as follows: IEC 60522 DIN EN 60522 ISO 554 DIN 50014 Amendments This standard differs from DIN 6867-1:1997-02 as fol

14、lows: a) For air kerma measurements, use of a spherical ionization chamber or a calibrated detector is required. b) For all tests, high frequency (multipulse) high voltage generators or at least 12-pulse high voltage generators shall be used. Use of 6-pulse high voltage generators is no longer permi

15、tted. c) The exposure times for determining speed and sensitometric curve shape have been reduced to reflect the latest state of the art. d) For the specified range of beam qualities, the phantom for Technique IV has been amended to reduce the air kerma rate. e) For determining speed and average gra

16、dient, the distance between X-ray tubes focal spot and screen/film system may now lie between 1,5 m and 4,0 m. f) Because the precision of modern X-ray tubes and high voltage generators is often much better than that of monitoring detectors, use of the latter is no longer prescribed. g) The uncertai

17、nty budget has been amended. h) The informative Annex A has been extended to include background information on measurements of speed and curve shape, on the selection of phantoms and on the dependence of speed on the energy spectrum of X-rays. Previous editions DIN 6867-1: 1981-06, 1985-04, 1997-02

18、DIN ISO 9236-1:2007-08 5 National Annex NA (informative) Bibliography DIN 50014, Artificial climates in technical applications Standard atmospheres DIN EN 60522, Determination of the permanent filtration of X-ray tube assemblies DIN ISO 9236-1:2007-08 6 Photography Sensitometry of screen/film system

19、s for medical radiography Part 1: Determination of sensitometric curve shape, speed and average gradient Introduction This part of ISO 9236 provides methods for determining the sensitometric curve shape, the average gradient and the speed of radiographic screen/film/filmholder/processing systems use

20、d in medical radiography, except in mammography and dental radiography. The sensitometric curve shape, which is also needed for the determination of other properties (as, for example, the modulation transfer function), is measured under low scatter conditions via intensity scale X-ray sensitometry,

21、preferably using an inverse square sensitometer. For the determination of the sensitometric curve shape, as well as for a subsequent determination of the average gradient from the measured curve, but not for speed, the irradiation of the screen/film/filmholder combination need to be measured only in

22、 relative units. Speed is measured in a separate way, under exposure conditions which simulate medical practice more closely, including realistic fractions of scattered radiation. Different types of medical exposures are simulated by using appropriate phantoms and X-ray tube voltages, and the screen

23、/film/filmholder combination is exposed behind the respective phantom. The irradiation is measured in absolute units of air kerma (gray, Gy) in order to determine the speed. Four different techniques are defined, differing in beam quality and fraction of scattered radiation, simulating the imaging o

24、f extremities, skull, lumbar spine and colon, and chest. Speed may be measured for each technique of interest. Owing to its dependence on X-ray energy and scatter, screen/film system speed varies widely in medical practice. The four measurement conditions described in this part of ISO 9236 provide v

25、alues that are representative of those found under practical conditions. DIN ISO 9236-1:2007-08 7 1 Scope This part of ISO 9236 specifies methods for the determination of the sensitometric curve shape, average gradient and speed of a single sample of a screen/film/filmholder/processing system for me

26、dical radiography. It is not applicable to special radiographic applications such as mammography, dental radiography and direct-exposing medical radiographic systems (see for example ISO 5799 3). The filmholder can be any means that ensures close screen/film contact and prevents the film from being

27、exposed to ambient light. In particular, the filmholder can be a light-tight vacuum bag, as often used in the laboratory, or a radiographic cassette as used in medical radiography. 2 Normative references The following referenced documents are indispensable for the application of this document. For d

28、ated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 5-2:2001, Photography Density measurements Part 2: Geometric conditions for transmission density ISO 5-3:1995, Photography Density measuremen

29、ts Part 3: Spectral conditions ISO 554:1976, Standard atmospheres for conditioning and/or testing Specifications IEC 60522:1999, Determination of the permanent filtration of X-ray tube assemblies 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.

30、1 screen/film system radiographic imaging system consisting of screen(s), film, filmholder and film processing NOTE Hereafter, screen/film/filmholder combinations will be referred to as “combinations” and will be referred to as “systems” when the processing is included. DIN ISO 9236-1:2007-08 8 3.2

31、air kerma K sum of the initial kinetic energies of all charged particles (e.g., electrons) liberated by uncharged particles (e.g., X-ray photons) from air molecules, divided by the mass of air in that volume where the charged particles are liberated NOTE The unit is the gray (Gy). 3.3 sensitometric

32、curve plot of the density of a processed photographic film as a function of the logarithm to the base 10 of the exposure 3.4 speed S quantitative measure of the response of the screen/film system to radiant energy for the specified conditions of exposure, processing and density measurement 3.5 avera

33、ge gradient Gslope of the straight line joining two specified points on a sensitometric curve 3.6 net density D density of an exposed and processed film minus the density of an unexposed and processed sample of that film 3.7 coverage factor k numerical factor, used as a multiplier of the combined st

34、andard uncertainty in order to obtain an expanded uncertainty NOTE The coverage factor is explained in the Guide to the expression of uncertainty in measurement 8. Its value is typically in the range of 2 to 3. The coverage factor is chosen based on the level of confidence desired. A coverage factor

35、 (k) of 2 generally will result in a level of confidence of approximately 95 %, and a coverage factor of 3 generally will result in a level of confidence of approximately 99 %. This association of confidence level and coverage factor is based on an assumption regarding the probability distribution o

36、f measurement results. 4 General requirements 4.1 Storage and handling conditions The film and screens shall be stored according to the manufacturers recommendations. Before and during exposures, the temperatures of the films and screens shall be maintained at 23 C 2 C (see ISO 554) and the moisture

37、 content of the film shall be such that it will be in equilibrium at a relative humidity of (50 20) %. 4.2 Safelights To eliminate the possibility of safelight illumination affecting the sensitometric results, all films shall be kept in total darkness during handling, exposure and processing. DIN IS

38、O 9236-1:2007-08 9 4.3 X-ray equipment For all tests described in this part of ISO 9236, high frequency (multipulse) high voltage generators or at least 12-pulse high voltage generators shall be used. For all tests described in this part of ISO 9236, X-ray tubes equipped with fixed anodes or rotatin

39、g anodes may be used. In either case, the target material shall be tungsten or a tungsten-based alloy. NOTE 1 The target is that part of the anode onto which the electron beam is directed to produce X-radiation. For technological reasons it is common practice to use alloys of tungsten with up to 10

40、% rhenium for the target, while other parts of the anode can consist of other materials (e.g. molybdenum). The permanent filtration of the X-ray tube and its housing, as defined in IEC 60522, shall be equivalent to 2,5 mm 0,2 mm of aluminium. NOTE 2 The permanent filtration of the X-ray tube and its

41、 housing is effected by permanently fixed materials intercepting the X-ray beam, which are not intended to be removed for any application. As the permanent filtration is usually stated on the X-ray tube housing and in the accompanying documents, its measurement, as described in IEC 60522, is not nec

42、essary. 4.4 Air kerma meter For the air kerma measurement, calibrated detectors shall be used. The uncertainty of air kerma measurement (level of confidence 95 %) shall be less than 3 % for collimated beams without scatter, and less than 5 % for radiation measurements behind the phantom when scatter

43、ed radiation is included. A spherical ionization chamber of 30 cm3to 100 cm3volume should be used for measurements where scattered radiation is involved. The chamber shall be calibrated for the beam qualities given in Table 2, including scattered radiation. The centre of the spherical chamber is to

44、be considered the reference point; the stem of the spherical chamber should point in a direction opposite to the radiation source. NOTE During calibration of the air kerma meter and during usage, scattered radiation originating not from the phantom but from, for example, the stem of the chamber, can

45、 be minimized in order to meet the specified uncertainty requirement. 4.5 Processing Screen/film systems, including either manual or automatic processing, may be tested in accordance with this part of ISO 9236. Processing should be carried out in accordance with the film manufacturers recommendation

46、s. Nothing shall be construed to require the disclosure of proprietary information. No processing specifications are described in this part of ISO 9236 in recognition of the wide range of chemicals and equipment used. Speed and average gradient values provided by film manufacturers generally apply t

47、o the system when the film is processed in accordance with their recommendations so that the photographic characteristics specified for the process are produced. Processing information shall be provided by the film manufacturer or others who quote speed and average gradient values and shall specify

48、the processing chemicals, times, temperatures, agitation, equipment and procedures used for each of the processing steps, and any additional information required to obtain the sensitometric results described. The values for speed and average gradient obtained using other processing procedures may di

49、ffer significantly. The processing conditions selected by a person using this part of ISO 9236 are, in any case, part of the system being tested. NOTE 1 Different speeds for a particular film can be achieved by varying the processes. However, these variations to the processes can cause other undesirable changes. In order to minimize any effects due to latent-image instability or process variability, all film samples shall be processed together, neither less than 30 min nor more than 4 h after exposure. Between exposure and proces