1、BRITISH STANDARD BS 7725-2.3: 1994 IEC 1223-2-3: 1993 Evaluation and routine testing in medical imaging departments Part 2: Constancy tests Section 2.3 Method for darkroom safelight conditionsBS7725-2.3:1994 This British Standard, having been prepared under the directionof the Health Care Standards
2、Policy Committee, waspublished under the authorityof the Standards Boardand comes into effect on 15February1994 BSI 10-1999 The following BSI references relate to the work on this standard: Committee reference HCC/73 Draft for comment 87/53432 DC ISBN 0 580 22799 5 Committees responsible for this Br
3、itish Standard 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 Physi
4、cal Sciences in Medicine (IPSM) Royal College of Radiologists Society of X-ray Technology Amendments issued since publication Amd. No. Date CommentsBS7725-2.3:1994 BSI 10-1999 i Contents Page Committees responsible Inside front cover National foreword ii Introduction 1 1 Scope and object 1 2 Referen
5、ces to other publications 1 3 Terminology 1 4 Test method 1 5 Calculation of safe handling time 3 6 Frequency of testing 3 7 Statement of compliance 3 Annex A Terminology Index of terms 4 Annex B Example of a form for the standardized test report 5 Annex C Guidance on action to be taken 5 Annex D Ra
6、tionale 6 List of references Inside back coverBS7725-2.3:1994 ii BSI 10-1999 National foreword This Section of BS7725 has been prepared under the direction of the Health Care Standards Policy Committee. It is identical with IECPublication1223-2-3:1993 Evaluation and routine testing in medical imagin
7、g departments Part2-3: Constancy tests Darkroom safelight conditions, prepared by the Technical Committee62 Electrical equipment in medical practice and published by the International Electrotechnical Commission (IEC). NOTEISO 8374:1986 referenced in clause2 is not quoted in this Technical Report. T
8、his 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 does not of itself confer immunity from
9、 legal obligations. Cross-references International Standard Corresponding British Standard IEC 788:1984 BS 6641:1985 Glossary of medical radiological terms (Identical) BS 7725 Evaluation and routine testing in medical imaging departments IEC 1223-1:1993 Part 1:1994 General (Identical) IEC 1223-2-1:1
10、993 Section 2.1:1994 Method for film processors (Identical) Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages1 to 6, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated.
11、 This will be indicated in the amendment table on the inside front cover.BS7725-2.3:1994 BSI 10-1999 1 Introduction Some provisions or statements in the body of this technical report require additional information. Such information is presented inAnnex D, Rationale. An asterisk in the left margin of
12、 a clause or subclause indicates the presence of such additional information. 1 Scope and object 1.1 Scope This technical report applies to darkrooms in X-ray facilities where any of the following unprocessed radiographic or photographic materials sensitive to light are handled: all types of SCREEN
13、FILM; NON-SCREEN FILM; photographic film for INDIRECT RADIOGRAPHY, as used for recording: OUTPUT IMAGES of X-RAY IMAGE INTENSIFIERS; other RADIOLOGICAL IMAGES after TRANSFER; photographic material for copying RADIOGRAMS; photographic material for making permanent images of information recorded by el
14、ectronic means, and presented on display tubes; for example: using hard copy cameras, or printed by other electronic means, for example: laser; or used in diagnostic equipment, such as for general RECONSTRUCTIVE TOMOGRAPHY; digital imaging; ultrasound; magnetic resonance techniques; in NUCLEAR MEDIC
15、INE. 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 EQUIPMENT, as described in IEC1223-1. 1.2 Object This technical report is intended
16、to ensure the adequacy of darkroom conditions. This technical report describes a method for testing the adequacy of the darkroom safelight conditions, and the freedom from extraneous actinic light. 2 References to other publications The following IEC/ISO publications are quoted in this technical rep
17、ort: IEC 788:1984, Medical radiology Terminology. IEC 1223-1:1993, Evaluation and routine testing in medical imaging departments Part1: General aspects. IEC 1223-2-1:1993, Evaluation and routine testing in medical imaging departments Part2-1: Constancy tests Film processors. ISO 8374:1986, Photograp
18、hy Determination of ISO safelight conditions. 3 Terminology This technical report contains a number of terms that are defined in IEC788, in IEC1223-1, and in IEC1223-2-1 (seeAnnex A, Terminology Index of terms). Where these terms are used with the meanings given in their definitions, they are printe
19、d 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 definition, but to be derived from the customary meaning o
20、f 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 and, if printed in capital letters, have meanings linked
21、to the definitions of the source terms concerned. The term: 4 Test method 4.1 Summary Exposure of a test film in the darkroom is used to detect fogging attributable to unsatisfactory conditions, particularly inappropriate safelight conditions, or leakage of extraneous actinic light. Common reasons w
22、hy darkroom conditions may cause fogged radiosensitive materials are as follows: faded or inappropriate safelight filters are used; safelight is too bright because the safelight lamp is of too high radiance; for example, in terms of rated power, type of lamp, inappropriate supply voltage; extraneous
23、 actinic light is reaching the working surface; “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. “specified” when used with parameters or conditions: refers to a value
24、 or arrangement to be chosen for the purpose under consideration and indicated usually in ACCOMPANYING DOCUMENTS.BS7725-2.3:1994 2 BSI 10-1999 actinic light is caused by light sources in the darkroom, such as leakage of white light, luminous panels; the correct distance from the safelight lamp to th
25、e working surface is not maintained; the materials sensitive to light are handled at places distant from the designated working surface. A sheet of radiographic or photographic film is pre-exposed to yield an optical density of approximately0,6 to1,0 when correctly developed. Thereafter, the pre-exp
26、osed test film is exposed to usual darkroom conditions in such a way that successive areas of the test film are exposed for different periods of time. After development of the test film, the optical densities of the various areas over the test RADIOGRAMS are measured and evaluated. 4.2 Test equipmen
27、t and test instruments 4.2.1 RADIOGRAPHIC CASSETTE For related CONSTANCY TESTS, the same RADIOGRAPHIC CASSETTE or magazine should be used. Its identification should be adequately marked and recorded. 4.2.2 Test film As the test film, a rectangular sheet of radiosensitive material of size at least12c
28、m by24cm is used. For the initial CONSTANCY TEST, a specimen of each type of radiographic or photographic material that is handled in the darkroom is used. For subsequent CONSTANCY TESTS, the type of material is used that has been shown to be the most sensitive, according to the results of the initi
29、al CONSTANCY TEST, and is of a spectral sensitivity typical for the materials handled in the specific darkroom. 4.2.3 FILM PROCESSOR The FILM PROCESSOR should have been tested according to IEC1223-2-1, and found to be satisfactory. 4.2.4 Densitometer Optical densities are measured with a densitomete
30、r which reads consistently within 0,02. 4.2.5 Covers Sheets of opaque material, for example cardboard, are used: a folded sheet to cover both sides of half the width of the test film, seeitem9) of4.3; a sheet to cover the other half of the test film in successive steps, as described in item11) of4.3
31、. The length and width of this sheet shall exceed those of the part of the film to be covered. 4.2.6 Timer A device for measuring time up to240s is used, that does not emit actinic light or other radiation. 4.3 Test procedure for checking the darkroom conditions The test is carried out as follows: 1
32、) The installation of the safelights and the safelight lamps provided should be checked, according to the instructions provided with the safelights and the radiographic or photographic materials used. 2) The filters are checked that they do not show any obvious sign of deterioration, such as fading,
33、 cracking or delamination. The presence of the appropriate filters and their correct position in the safelights are checked and, where relevant, replaced and adjusted. 3) All the safelights and other lights in the darkroom are switched off. 4) *After the eyes have become dark adapted (about5min to15
34、min), the darkroom is searched for light leakage. Particular attention is paid to the light seals around the working surface, those of FILM PROCESSORS, passboxes, darkroom doors, ceilings (suspended ceilings can leak light from surrounding rooms). Any leakage of actinic light detected by this method
35、 is eliminated, wherever practicable. NOTEIf the use of fluorescent light cannot be avoided in areas where radiosensitive materials or instruments are handled, special care must be taken that they will not fog or impair the same. 5) *After freedom from light leakage is ensured, indicator lights, pil
36、ot lights and other luminous panels on equipment are covered with opaque material. Clocks with luminous dials are removed from the darkroom. 6) The test film is loaded into the appropriate cassette or magazine. 7) *The loaded cassette or magazine is handled as for normal working conditions, the test
37、 film is pre-exposed to X-RADIATION so that an optical density on the test RADIOGRAM in the range of0,6 to1,0 is produced with normal processing.BS7725-2.3:1994 BSI 10-1999 3 8) With all lights in the darkroom still switched off or covered according to3) and5) above, the pre-exposed test film is tak
38、en out of the cassette, and placed on the working surface where unprocessed radiographic and photographic materials are normally handled. SINGLE EMULSION FILM is placed with the emulsion side facing upwards. For subsequent tests, the same place on the working surface is always used, to ensure reprod
39、ucibility of the test. 9) Both sides of one half of the test film are covered with a straight-edged folded piece of opaque material parallel to the longitudinal axis of the test film. This half of the test film remains covered throughout10) and11) of this procedure. 10) All safelights are switched o
40、n, the indicator lights, pilot lights and any luminous panels uncovered, and clocks replaced. 11) The uncovered half of the test film is exposed to the darkroom conditions for increasing periods of time by progressively covering it in increments, preferably of4cm, with the second sheet of the opaque
41、 material, which is moved along the length of the test film. The uncovered area of the test film is exposed and covered in successive steps for periods of30s, 30s, 60s, 120s and240s in order to produce steps with total exposure times of30s,60s, 120s, 240s, and480s. NOTEThe time during which the unco
42、vered test film is handled between individual steps should be kept to a minimum. 12) As soon as the last exposure period has expired, the safelights are switched off, and the test film is developed. 13) Using the densitometer, the optical densities of the areas exposed during the different total exp
43、osure times are measured, as well as the optical density of the unexposed area. If a densitometer is not available, see5.2 for visual comparison. 14) The values of optical densities are recorded in the test report; seeAnnex B. 5 Calculation of safe handling time 5.1 Determination based on measuremen
44、ts A portion of the exposed area of the RADIOGRAM is identified, that has an optical density closest to0,05 above that of the unexposed area. The total exposure time t for that portion of the RADIOGRAM is determined. The safe handling time for the darkroom is expressed as0,5t. 5.2 *Determination by
45、visual comparison A strip of opaque material about3mm wide is placed on the RADIOGRAM so as to cover the border between the unexposed and exposed areas. The total exposure time t is determined for that portion of the exposed area of which a visible difference from the unexposed area is just apparent
46、. The safe handling time is expressed as0,5t. 5.3 Safe handling time The safe handling time shall not be less than60s, and should be longer if normal practices necessitate. 5.4 Action to be taken If the safe handling time is unacceptable, or has decreased significantly since the last CONSTANCY TEST,
47、 the test should be repeated: a) with the safelights switched off, and the indicator lights, pilot lights, and any luminous panels covered, and clocks removed; b) with the safelights switched off, and the indicator lights, pilot lights, and any luminous panels uncovered, and clocks present; c) with
48、the safelights switched on, and the indicator lights, pilot lights, and any luminous panels covered, and clocks removed. The results of these tests are evaluated to identify cause(s) of fogging. If necessary, the CONSTANCY TEST is repeated on individual safelights, indicator lights, pilot lights, cl
49、ocks, etc. See alsoAnnex D. 6 Frequency of testing Every darkroom should be tested, using the procedure given in4.3, and the determination described in5.1 and5.2: at regular intervals, at least annually; when an increase in fogging of radiographic or photographic materials is suspected, which cannot be attributed to either the FILM PROCESSOR or the film storage conditions; when a new type of radiographic or photographic material is introduced; when major changes have taken place in the darkroom. 7 Statement of compliance
