ANSI IT2.41-1997 Photography - Sensitometry of Screen Film Systems for Medical Radiography - Part 1 Determination of Sensitometric Curve Shape Speed and Average Gradient《摄影.医疗放射照相术.pdf

1、P _ STD*ANSI IT?-VI-ENGL 1797 0724150 0537235 777 = ANSI/ISO 9236-1- I996, A NSUNA PM I T2.41- 1997 for Photography - Sensitometry of Screen/Flm Systems for Medical Radiography - Part I: Determination of Sensitometric Curve Shape, Speed and Average Gradient This materi 1 is reproduced from American

2、National Standard k=A 1 4 , copyright if 7 , with permission of the American National Standards Institute, Inc. Not for resale. No part of this publication may be copied or reproduced in any form, electronic retrieval system or otherwise, without the prior written permission of the American Naiional

3、 Standards Institute, Inc., 1 I West 42nd Street, New York, New York 10036. -AIA American National Standards Institute 1 77 West 42nd Street New York, New York 70036 STD-ANSI ITZ-qL-ENGL L777 072qL50 053723b 825 = American National Approval of an American National Standard requires review by ANSI th

4、at the requirements for due process, consensus, and other criteria for approval have been met by the standards developer. Standard Consensus is established when. in the iudament of the ANSI Board of Standards Review, substantial agreemeit Kas been reached by directly and materially affected interest

5、s. Substantial agreement means much more than a simple majority, but not necessarily unanimity. Consensus requires that all views and objections be considered, and that a concerted effort be made toward their resolution. The use of American National Standards is completely voluntary; their existence

6、 does not in any respect preclude anyone, whether he has approved the standards or not, from manufacturing, marketing, purchasing, or using products, processes, or procedures not conforming to the standards. The American National Standards Institute does not develop standards and will in no circumst

7、ances give an interpretation of any American National Standard. Moreover, no person shall have the right or authority to issue an interpretation of an American National Standard in the name of the American National Standards Institute. Requests for interpretations should be addressed to the secretar

8、iat or sponsor whose name appears on the title page of this standard. CAUTION NOTICE: This American National Standard may be revised or withdrawn at any time. The procedures of the American National Standards Institute require that action be taken periodically to reaffirm, revise, or withdraw this s

9、tandard. Purchasers of American National Standards may receive current information on all standards by calling or writing the American National Standards Institute. Published by American National Standards Institute 11 West 42nd Street, New York, New York 10036 Copyright O 1997 by American National

10、Standards Institute All rights reserved. No part of this publication may be reproduced in any form, in an electronic retrieval system or otherwise, without prior written permission of the publisher. Printed in the United States of America APSI .5C597/28 ANSVIS0 9236-1 -1996, ANSUNAPM IT2.41-1997 Ame

11、rican National Standard for Photography - Sens i to met ry of Scree n/F i I m Systems for Medical Radiography - Part 1 : Determination of Sensitometric Curve Shape, Speed and Average Gradient Secretariat National Association of Photographic Manufacturers, Inc. Approved April 17, 1997 American Nation

12、al Standards Institute, Inc. Contents Page Foreword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . III Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . .iv . 1 2 3 4 5 6 7 8 9 10 Scope . 1 Normative references . . . . 1 Definitions . . 1 General requirements .

13、. . 2 Determination of sensitometric curve shape 3 Determination of average gradient . 7 Determination of speed . 7 Speed and average gradient determination without sensitometric curve . . . . . . .14 Accuracy . 15 Test report 15 Tables 1 2 Figures Beam qualities for the determination of the sensito

14、metric curve shape . 4 Specification of techniques 9 Geometric Set-up of the inverse-square-law sensitometer for exposure of the screen/film combination 5 Geometric Set-up for calibration of the inverse-square-law sensitometer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

15、 6 Sensitometric curve 8 Phantom for technique I 9 Geometric Set-up for adjustment of beam qualities used for techniques I, II, III and IV . 11 Geometric Set-up for the measurement of speed (techniques I, II and Ill) . 12 Geometric Set-up for the measurement of speed (technique IV) . 13 Annex A Bibl

16、iography 16 ii STD-ANSI ITZ-41-ENGL 1997 0724350 0537237 534 Foreword (This foreword is not part of American National Standard ANSIASO 9236-1-1996, ANSVNAPM lT2.41-1997. The text of this document is identical to IS0 9326-1 : 1996.) IS0 (the International Organization for Standardization) is a worldw

17、ide fed- eration of national standards bodies (IS0 member bodies). The work of preparing International Standards is normally carried out through IS0 tech- nical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented o

18、n that committee. International organizations, governmental and non-gov- ernmental, in liaison with ISO, also take part in the work. IS0 collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. Draft International Standards ado

19、pted by the technical committees are cir- culated to the member bodies for voting. Publication as an International Standard requires approval by at least 75% of the member bodies casting a vote. International Standard IS0 9236-1 was prepared by Technical Committee ISOTTC 42, Photography. It contains

20、 one annex which is informative. Suggestions for improvement of this standard will be welcome. They should be sent to the National Association of Photographic Manufacturers, Inc., 550 Mamaroneck Avenue, Suite 307, Harrison, NY 10528-1 61 2, e-mail: natlstds . This standard was processed and approved

21、 for submittal to ANSI by NAPM Technical Committee IT2 on Image Evaluation. Committee approval of the standard does not necessarily imply that all committee members voted for its approval. At the time this standard was approved, the IT2 Committee had the following members: Michael R. Goodwin, Chairm

22、an Jack Holm, Vice-chairman James E. Harvey, Secretary Organization Represented Name of Representative American Roentgen Ray Society Joel Gray Association for Engineering Graphics and Imaging Systems . Philip P. Nowers Association for Information and Image Management (Liaison) . Marilyn Wright Azon

23、Corporation Bill Neithardt Canadian Standards Association (Liaison) . Trevor Smith CGATS . Richard S. Fisch Graphic Communication Association Norman W. Scharpf Graphic Microsystem . James R. Cox GTI Graphic Technology, Inc. Charles G. Saleski National Association of Photographic Manufacturers, Inc.

24、. Carolyn Franceschi Michael R. Goodwin Thomas McKeehan (Alt.) Brian E. Reed (Alt.) Alex Pendleton Thomas Lumenello (Alt.) Daniel E. Sinto Joseph Helm (Alt.) Robert L. Seyfert James E. Harvey (Alt.) . III Organization Represented Name of Representative Robert A. Uzenoff Robert D. Whittall David W. B

25、utcher (Alt.) Peter Krause (Alt.) Photographic Society of America . Jack Holm Professional Photographers of America . Robert M. Opfer PSI Associates William F. Voglesong Radiological Society of North America . Homer L. Twigg, Jr. rhohnetric Associates . David L. Spooner Schawk, Inc . Paul R. Guy Sta

26、ndards and Technology Daniel J. Dummer U.S. Department of the Army . Calvin F. Douglas Federal Supply Services Martin Robinson Charles C. Rogers (Alt.) U.S. Department of Commerce - National Institute of Jack J. Hsia U.S. Genera! Services Administration - Introduction This part of IS0 9236 provides

27、methods for determining the sensitometric curve shape, the average gradient and the speed of radiographic screen/film/filmholder/processing systems used in medical radiography, except in mammography and dental radiography. The sensitometric curve, which is also needed for the determination of other

28、properties (as, for example, the modulation transfer function) is measured under low scatter conditions via intensity scale X-ray sensitometry, preferably using an inverse square sensitometer. Since it is unlikely that the curve shape will be energy dependent within the kilovolt range covered by thi

29、s part of 1SO 9236, any one of the four beam qualities corresponding to those used for speed determination may be used for determining curve shape. For the determination of the sensitometric curve shape, the irradiation of the screenlfilmifilmholder combination need be measured only in relative unit

30、s. While the average gradient is determined from the sensitometric curve shape, speed must be measured in a separate way, since the exposure conditions should simulate as closely as possible those which are used in practice. Therefore, scattered radiation is included, accompanied by a slight change

31、of beam quality compared to the beam quality used for intensity scale sensitometry. The exposure is simulated by using appropriate phantoms and tube voltages. The screen/film/filmholder combination is exposed behind the phantom. The exposure is measured in absolute units (gray, Gy) in order to deter

32、mine the speed. Speed is generally dependent on X-ray energy and the amount of scattered radiation emerging from the patient. Therefore, a wide variety of speed values may be expected under practical conditions. The four measurement conditions described in this part of IS0 9236 provide values for sp

33、eed and average gradient which are representative of those found under practical conditions. Four different techniques are offered, differing in beam quality and fraction of scattered radiation. These techniques simulate four different scenarios of the practice: imaging extremities; skull; lumbar sp

34、ine and colon; and chest. Speed may be measured for each technique of interest. iv STD.ANS1 ITZ-qL-ENGL 1997 = 0724350 0539241 192 = AMERICAN NATIONAL STANDARD ANSUISO 9236-1-1996, ANSIINAPM IT2.41-1997 American National Standard for Photography - Sensitometry of Screen/Film Systems for Medical Radi

35、ography - Part 1 : Determination of Sensitometric Curve Shape, Speed and Average Gradient 1 Scope This part of IS0 9236 specifies methods for determination of the sensitometric curve shape, average gradient and speed of a single sample of a screeiilfililmhoIder/proceCsing system in medical radiograp

36、hy. Special radiographic applications such as mammography, dental radiography and directexposing medical radiographic systems (see for example IS0 5799) are excluded. The filmholder may be any means which ensures close screenfiilm contact and prevents the film from being exposed to ambient light. In

37、 particular, the filmholder may be a light-tight vacuum bag, as often used in the laboratory, or a radiographic cassette as used in medical radiography. NOTE - Hereafter, screen/filrn/filmholder combinations will be referred to as “combinations“ and will be referred to as “systems“ when the processi

38、ng is included. 2 Normative references The following standards contain provisions which, through reference in this text, constitute provisions of this part of IS0 9236. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements bas

39、ed on this part of IS0 9236 are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. Members of IEC and IS0 maintain registers of currently valid International Standards. IS0 5-2:1991, Photography - Density measurements - Part 2: Geometric

40、conditions for transmission density. IS0 5-3: 1995, Photography - Density measurements - Pan 3: Spectral conditions. IS0 554: 1 976, Standard atmospheres for conditioning and/or testing - Specifications. 3 Definitions For the purposes of this part of IS0 9236, the following definitions apply. 3.1 ai

41、r kerma, K: That energy which is transferred by ionizing radiation (for instance X-rays) to air molecules divided by the mass of air in that volume where the energy is released. The unit is the gray (Gy). 3.2 sensitometric curve: Plot of the density of a processed photographic film as a function of

42、the logarithm of the exposure. 1 ANSMSO 9236-1 -1 996, ANSVNAPM IT2.41-1997 3.3 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. 3.4 average gradient, E: The slope of the straight

43、line joining two specified points on a sensitometric curve. 3.5 net density, D: Density of an exposed and processed film minus the density of an unexposed and processed sample of that film. 4 General requirements 4.1 Storage and handling conditions The film and screens shall be stored according to t

44、he manufacturers recommendations. Before and during exposures, the temperatures of the films and screens shall be maintained at 23 “C f 2 “C (see IS0 554) and the moisture content of the film shall be such that it will be in equilibrium at a relative humidity of (50 f 20) %. 4.2 Safelights To elimin

45、ate the possibility of safelight illumination affecting the sensitometric results, all films shall be kept in total darkness during handling, exposure and processing. 4.3 X-ray equipment For all tests described in this part of IS0 9236, a the stem of the spherical chamber should point in a direction

46、 opposite to the focus direction. If a cylindrical chamber is used, the ratio of diameter to height should be at least 4 to 1. 4.4 Processing Screen/film systems, including either manual or automatic processing, may be tested in accordance with this part of IS0 9236. Processing should be carried out

47、 in accordance with the film manufacturers recommendations. Nothing shall be construed to require the disclosure of proprietary information. No processing specifications are described in this part of IS0 9236 in recognition of the wide range of chemicals and equipment used. Speed and average gradien

48、t values provided by film manufacturers generally apply to 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 q

49、uote speed and average gradient values and shall specify 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 differ significantly. The processing conditions selected by a person using this part of IS0 9236 are, in any case, part of the system being tested. Different speeds for a particular film may be achieved by vary