1、BRITISH STANDARD BS 7725-2.1: 1994 IEC 1223-2-1: 1993 Evaluation and routine testing in medical imaging departments Part 2: Constancy tests Section 2.1 Method for film processorsBS7725-2.1:1994 This British Standard, having been prepared under the directionof the Health Care Standards Policy Committ
2、ee, waspublished under the authorityof the Standards Boardand comes into effect on 15February 1994 BSI 11-1999 The following BSI references relate to the work on this standard: Committee reference HCC/73 Draft for comment 88/56155 DC ISBN 0 580 22800 2 Committees responsible for this British Standar
3、d The preparation of this British Standard was entrusted by the Health Care Standards Policy Committee (HCC/-) to Technical Committee HCC/73, upon which the following bodies were represented: British Institute of Radiology College of Radiographers Department of Health Institute of Physical Sciences
4、in Medicine (IPSM) Royal College of Radiologists Society of X-ray Technology Amendments issued since publication Amd. No. Date CommentsBS7725-2.1:1994 BSI 11-1999 i Contents Page Committees responsible Inside front cover National foreword ii Introduction 1 1 Scope and object 1 2 References to other
5、publications 1 3 Terminology 1 4 General aspects of constancy tests 2 5 Test procedure 3 6 Action to be taken 4 7 Statement of compliance 5 Annex A Terminology Index of terms 8 Annex B Example of a form for the standardized test report 9 Annex C Guidance on action to be taken 14 Annex D Rationale 14
6、 Annex E Procedures for initial setting up of the film processor 16 Figure 1 Variation in film base plus fog density, speed index and contrastindex with developer temperature (optimization procedure) 6 Figure 2 Example of a control chart displaying the film base plus fogdensity,speed index and contr
7、ast index as a function of time 7 List of references Inside back coverBS7725-2.1:1994 ii BSI 11-1999 National foreword This Section of BS 7725 has been prepared under the direction of the Health Care Standards Policy Committee. It is identical with IEC 1223-2-1:1993 Evaluation and routine testing in
8、 medical imaging departments Part 2-1: Constancy tests Film processors, prepared by the Technical Committee 62 Electrical equipment in medical practice and published by the International Electrotechnical Commission (IEC). NOTEISO 4090:1991, ISO 8374:1986 and ISO 8402:1986 referenced in clause 2 are
9、not quoted in this Technical Report. This error has been reported to the relevant body for action. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard d
10、oes not of itself confer immunity from legal obligations. Cross-references International Standard Corresponding British Standard IEC 601-1:1988 BS 5724 Medical electrical equipment (without amendment No.1, 1991) Part 1:1989 General requirements for safety (Identical) IEC 788:1984 BS 6641:1985 Glossa
11、ry of medical radiological terms (Identical) IEC 1223-1:1993 BS 7725 Evaluation and routine testing in medical imaging departments Part 1:1994 General (Identical) IEC 1223-2-3:1993 Section 2.3:1994 Method for darkroom conditions (Identical) Summary of pages This document comprises a front cover, an
12、inside front cover, pagesi andii, pages1 to18, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.BS7725-2.1:1994 BSI 11-1999 1 Introduction Some
13、provisions or statements in the body of this technical report require additional information. Such information is presented in Annex D, Rationale. An asterisk in the left margin of a clause or subclause indicates the presence of such additional information. 1 Scope and object 1.1 Scope This technica
14、l report applies to those components of X-RAY EQUIPMENT which process RADIOGRAPHIC FILM and other photographic materials in X-ray facilities in which any of the following radiographic or photographic materials are handled: all types of SCREEN FILM; NON-SCREEN FILM; photographic film for INDIRECT RAD
15、IOGRAPHY, as used for recording OUTPUT IMAGES of X-RAY IMAGE INTENSIFIERS, other transferred RADIOLOGICAL IMAGES; photographic material for copying RADIOGRAMS; photographic material for making permanent images of information recorded by electronic means, and presented on display tubes, for example:
16、hard copy cameras, or printed by other electronic means, for example: laser; as used in diagnostic equipment such as for general RECONSTRUCTIVE TOMOGRAPHY, digital imaging, ultrasound, NUCLEAR MEDICINE, magnetic resonance. The method described in this technical report is intended primarily for autom
17、atic FILM PROCESSORS, but may be adapted for testing equipment for manual processing. This technical report is a part of a series of Particular Publications (standards and technical reports) which will describe test methods for the constancy of properties of various subsystems of diagnostic X-RAY EQ
18、UIPMENT, as described in IEC1223-1. 1.2 Object* This technical report describes constancy parameters in FILM PROCESSORS, and a method to check these parameters, in order to ensure that the conditions for producing consistent RADIOGRAMS of adequate quality on radiographic and photographic materials a
19、re maintained. 2 References to other publications The following IEC/ISO publications are quoted in this technical report: IEC 601-1:1988, Medical electrical equipment Part 1: General requirements for safety. Amendment No. 1, 1991 IEC 788:1984, Medical radiology Terminology. IEC 1223-1:1993, Evaluati
20、on and routine testing in medical imaging departments Part 1: General aspects. IEC 1223-2-3:1993, Evaluation and routine testingin medical imaging departments Part 2-3:Constancy tests Darkroom safelight conditions. ISO 4090:1991, Photography Film dimensions Medical radiography. ISO 8374:1986, Photog
21、raphy Determination of ISO safelight conditions. ISO 8402:1986, Quality Vocabulary. 3 Terminology 3.1 Use of terms This technical report contains a number of terms that are defined in IEC 788, in IEC 1223-1 and in IEC 1223-2-1 (see Annex A, Terminology Index of terms). Where these terms are used wit
22、h the meanings given in their definitions, they are printed in capital letters to signify that the defined meaning applies. Words forming a part of the whole of any defined term may also appear in lower-case letters. In that event, the meaning is not intended necessarily to correspond to any formal
23、definition, but to be derived from the customary meaning of the words in the language and from the actual context. Terms derived from those formally defined (for example, the plural form of a term defined in the singular or the adjectival form of a term defined as a noun), are used where appropriate
24、 and, if printed in capital letters, have meanings linked to the definitions of the source terms concerned. The term: “specific” when used with parameters or conditions: refers to a particular value or standardized arrangement, usually to those required in an IEC publication or a legal requirement.
25、“specified” when used with parameters or conditions: refers to a value or arrangement to be chosen for the purpose under consideration and indicated usually in ACCOMPANYING DOCUMENTS.BS7725-2.1:1994 2 BSI 11-1999 3.2 Definitions 3.2.1 FILM PROCESSOR for use in MEDICAL DIAGNOSTIC RADIOLOGY, a combina
26、tion of equipment and devices to process the latent radiological information, recorded on, or transferred to, radiographic or photographic material, into a permanent, visible image 3.2.2 FILM BASE PLUS FOG DENSITY for CONSTANCY TESTS in X-RAY EQUIPMENT, the optical density in an area of the RADIOGRA
27、M on the processed control film, that has not been exposed to light from a sensitometer 3.2.3 SPEED INDEX for CONSTANCY TESTS in X-RAY EQUIPMENT, the specific value of optical density in an area of the RADIOGRAM produced by a constant exposure to a light source NOTEThe value of SPEED INDEX normally
28、is established at an optical density in the range from 0,8 to 1,2 above that of FILM BASE PLUS FOG DENSITY. 3.2.4 CONTRAST INDEX for CONSTANCY TESTS IN X-RAY EQUIPMENT, difference between the SPEED INDEX and the value of optical density produced by a constant exposure from a light source, greater th
29、an that used for producing the SPEED INDEX NOTE 1This exposure is normally aimed at an optical density in the range from 1,6 to 2,0 above that of FILM BASE PLUS FOG DENSITY. NOTE 2SPEED INDEX and CONTRAST INDEX are used as constancy parameters and are intended to facilitate the routine checks descri
30、bed in this technical report. They must not be confused with the sensitometric definitions of sensitivity in terms of speed and average gradient. 4 General aspects of CONSTANCY TESTS 4.1 Principle of the test procedures In an initial series of CONSTANCY TESTS, the BASELINE VALUES of the three consta
31、ncy parameters of the FILM PROCESSOR (FILM BASE PLUS FOG DENSITY, SPEED INDEX and CONTRAST INDEX) are determined. This is achieved by exposing control films under specific conditions prior to processing them in the FILM PROCESSOR under test. NOTEWhilst it is possible to use pre-exposed films availab
32、le from the manufacturers of photosensitive materials, this method is not recommended in preference to the use of freshly exposed control films because of the differences in the characteristic response of the pre-exposed films from those currently in use in the X-ray department. The subsequent perfo
33、rmance of the FILM PROCESSOR is monitored routinely by processing further control films, and the measured values of the constancy parameters are compared with the BASELINE VALUES in order to detect deviations from constancy. In X-ray departments where more than one FILM PROCESSOR is in use, the perf
34、ormance of several FILM PROCESSORS can be harmonized by adjusting their individual developer temperatures. This is greatly facilitated if all the FILM PROCESSORS use the same chemistry; see Annex E. 4.2 Test equipment 4.2.1 Control films* Control films of photographic or RADIOGRAPHIC FILM are produc
35、ed by exposure under a stepwedge to light emitted from a calibrated and stable light source (sensitometer). The control films should be of the same type as the radiographic material(s) normally used in the X-ray department and should be stored under the same conditions. As far as is practicable, con
36、trol films used for successive CONSTANCY TESTS should be of the same type and batch/emulsion number, and should be taken from the same package. One package should not be in use for a period exceeding six months, nor beyond its expiry date. Prior to changing the batch or type of radiographic material
37、 used for the control films, it is necessary to adjust the BASELINE VALUES of the constancy parameters. This is achieved by simultaneously processing control films from both the current and replacement batches. The appropriate degree of adjustment is then determined from a comparison of the measured
38、 constancy parameters. If more than one type of radiographic material is processed in the same FILM PROCESSOR, it may be necessary to use several series of control films, one representative of each type of radiographic material, in order to allow for differences in characteristic response of the dif
39、ferent types of material. 4.2.2 Sensitometer Control films should be exposed by means of a sensitometer equipped with a suitable stepwedge. The light output should be reproducible to within 2 %. The sensitometer should provide at least two levels of exposure which result in optical densities on the
40、processed control films: a) within the range 0,8 to 1,2 above FILM BASE PLUS FOG DENSITY, and b) within the range 1,6 to 2,0 above FILM BASE PLUS FOG DENSITY.BS7725-2.1:1994 BSI 11-1999 3 No part of the control film should be exposed to light from the sensitometer in order to permit measurement of t
41、he FILM BASE PLUS FOG DENSITY on the processed control film. A stepwedge containing a series of steps will enable differences in the sensitivity of different types of control film to be taken into account. 4.2.3 Densitometer Optical densities are measured with a densitometer which reads consistently
42、 within 0,02. 4.2.4 Thermometer* The temperatures of the processing solutions are measured by a metal stem or digital thermometer to within 0,1 C. A mercury in glass thermometer shall not be used. 4.3 FILM PROCESSOR: Cleaning, maintenance and log book* Prior to any CONSTANCY TEST, it shall be ensure
43、d that the FILM PROCESSOR is set up in accordance with the instructions given in the ACCOMPANYING DOCUMENTS for the radiographic materials, the FILM PROCESSOR and the chemicals; the optimum developer temperature is known either as determined, see Annex E, or as given in the ACCOMPANYING DOCUMENTS fo
44、r the radiographic materials; the FILM PROCESSOR is maintained in accordance with the instructions given in the ACCOMPANYING DOCUMENTS for the radiographic materials, the FILM PROCESSOR and the chemicals. A maintenance log-book attached to each FILM PROCESSOR is essential in order to record: when ma
45、intenance is carried out; when the processing solutions are changed, when new replenishment solution is added, and when any other changes relevant to the performance of the FILM PROCESSOR were made. 4.4 Darkroom safelight conditions Where, during a CONSTANCY TEST according to this technical report,
46、radiographic or photographic materials are openly handled prior to the test, it must be insured that the darkroom conditions as well as the film storage conditions are satisfactory, and, if necessary, that CONSTANCY TESTS according to IEC 1223-2-3 have been carried out. 5 Test procedure 5.1 Determin
47、ation of constancy of FILM PROCESSOR performance 5.1.1 Method a) It should be assured that: the FILM PROCESSOR has undergone routine maintenance; and its performance is satisfactory; see Annex E. b) The FILM PROCESSOR is set at the selected optimum temperature for the development solution. c) The “s
48、tart-up” procedure recommended in the ACCOMPANYING DOCUMENTS is followed, and a period of 30 min allowed for the solution temperatures to stabilize. d) The solution and wash water temperatures are checked. If feasible, the replenishment rates, wash water flow rate, and dryer temperatures are measure
49、d. Temperatures and flow rates are adjusted if necessary and allowed to stabilize. e) Using the sensitometer, a series of two to six control films are exposed. It is sufficient to expose only one side of a DOUBLE EMULSION FILM. f) *After at least 30 min but no longer than 4 h, the control films are processed. The control films are processed so that the leading edge is the least exposed end of the stepwedge pattern. The sheets of control film are passed into the FILM PROCESSOR always at the same side of the feed
