1、CENELEC ENxbL2b2-3 94 3404583 OL49LY3 629 BRITISH STANDARD Characteristics of electro-optical X-ray image intensifiers for medical electrical equipment Part 3. *Determination of the luminance distribution and luminance non-uniformity The European Standard EN 61262-3 : 1994 has the status of a Britis
2、h Standard BS EN 61262-3 : 1995 IEC 1262-3 : 1994 CENELEC EN*bl12b2-3 94 m 3404583 0149144 565 m BS EN 61262-3 : 1996 This British Standard, having been prepared under the direction of the Health and Environment Sedor Board (W-), was published under the authority of the Standards Board and comes int
3、o effect on 15 March 1995 O BSI 1995 The following BSI references relate to the work on this standard: Committee reference HCC/72 Draft for comment 94/501343 DC ISBN O 680 23694 7 Committees responsible for this British Standard The preparation of this British Standard was entrusted to %chnical Comm
4、ittee HCC/72, Image intensifiers, upon which the foliowing bodies were represented : Association of X-ray Equipment Manufacturers (BEAMA Ltd.) British Institute of Radiology College of Radiographers Institute of Physical Sciences in Medicine (Ipsm) Amendments issued since publication Amd. No. I Date
5、 I Rxt affected CENELEC EN*bLZb2-3 94 = 3404583 0147145 4TL BS EN 61262-3 : 1995 Contents hge Committees responsible Inside front cover National foreword ii Foreword 2 Rxt of EN 61262-3 4 i CENELEC EN*b12b2-3 94 m 340Y583 0149146 338 m BS EN 61262-3 : 1995 National foreword This British Standard has
6、 been prepared by Bchnical Committee HCC/72 and is the English language version of EN 61262-3 : 1994 Medical electrical equi- - Chamctertics of electro-optical X-ray image in implies that compliance with a requirement is strongly recommended but is not mandatory for compliance with the standard; imp
7、lies that compliance with a requirement is permitted to be accomplished in a particular manner, for compliance with the standard; and the following words have the meaning: - “specific“ - “specified“ when used in combination with parameters or conditions: refers to a particular value or standardized
8、arrangement, usually to those required in an IEC standard or a legal requirement; see IEC 788, rm-74-01. when used in combination with parameters or conditions: refers to a value or arrangement to be chosen for the purpose under consideration and indicated usually in the ACCOMPANYING DOCUMENTS; see
9、JEC 788, rm-74-02. - “designed for“ when used in standards to characterize equipment, devices, components or arrangements:. designates an intended and usually apparent purpose or use for the product. CENELEC ENubLZb2-3 94 3404583 OL49L53 578 Page 7 EN 61262-3 : 1994 4 Requirements 4.1 Test ser-up a)
10、 The SED shall be 100 cm f 1 cm. b) The FOCAL SPOT of the X-RAY TUBE shall be on the CENTRAL AXIS. c) The distance between the FOCAL SPOT of the X-RAY TUB and any ADDED FILTERS shall not exceed 33 cm. d) The X-RAY FIELD shall cover the ENTRANCE FIELD entirely, but its area shall not exceed the ENTRA
11、NCE FIELD area by more than 10 %. This limitation of the X-RAY FIELD shall be made by a DIAPHRAGM placed immediately in front of the ENTRANCE PLANE. The BEAM LIMITING DEVICE Of the X-RAY SOURCE ASSEMBLY shall be Used to limit the X-RAY BEAM on this DIAPHRAGM. The DIAPHRAGM shall provide an ATENUATIO
12、N FIATIO Of at least 100 for !he quantity AIR KERMA RATE. 4.2 X-RAY IMAGE INTENSIFIER - Operating conditions a) The XRII shall be operated under the conditions for NORMAL USE as specified by the manufacturer. b) NO ANTI-SCAITER GRID or protective cover shall be Used. c) In the case of multiple-field
13、 XRIIs, the measurement shall be made for the largest specified ENTRANCE FIELD. Measurements for other ENTRANCE FIELDS are optional. 4.3 input radiation a) The TOTAL FiLTRAnoN of the incident X-RAY BEAM shall be 22,5 mm f 0,5 mm of aluminium equivalent of which at least 20 mm is aluminium (99,9 % pu
14、rity). The HALF-VALUE LAYER at the position corresponding to the CENTRE OF THE ENTRANCE FIELD shall be 7,O mm Al f 0,2 mm Al (99,9 % purity). This condition corresponds to an approximate X-RAY TUBE VOLTAGE of 75 kV. b) The AIR KERMA RATE in the ENTRANCE PLANE shall be such that linear operation of t
15、he XRII and the detectorsemployed in the measurement is ensured. An AIR KERMA RATE of 1 pGy s- to 100 pGy s- is recommended. c) The temporal fluctuations of the AIR KERMA RATE shall not impair the measurement uncertainty by more than 2 %. If the AIR KERMA RATE measurements or the luminance measureme
16、nts are made at different time instances, the X-RAY TUBE output shall be monitored and the results of the measurements shall be corrected to meet this requirement. d) The AIR KERMA RATE at any location in the ENTRANCE FIELD shall not be less than 70 % Of the highest value of the AIR KERMA RATE in th
17、e ENfRANCE FIELD. 4.4 TEST DEVICE Not used. Page 8 EN 61262-3 : 1994 4.5 Measurement equipment 4.5.1 Device for measuring the uniformity of the X-RAY FIELD a) Any device measuring a quantity which has a known relationship to the relative AIR KERMA RATE may be used, for example, a photomultiplier tub
18、e coupled to a scintillator or a NON-SCREEN FILM with a known sensitometric curve. The device shall have such a precision, that the error of measuring relative AIR KERMA RATE is 2 % or less. No particular specifications are required with respect to the absolute accuracy of these measurements. b) The
19、 maximum diagonal of the effective measuring area of the device shall not exceed 10 % Of the ENTRANCE FIELD SIZE. 4.5.2 Device for measuring the luminance of the OUTPUT SCREEN a) Any device measuring a quantity which has a known relationship to the relative luminance may be used. The device shall ha
20、ve such a precision, that the error of measuring relative luminance is 2 % or less. No particular specifications are required with respect to the absolute accuracy of these measurements. b) The device shall measure the relative luminance in the direction perpendicular to the plane defined by the OUT
21、PUT SCREEN. The acceptance cone of the detector shall be small enough to avoid errors when measurement approaches a dark edge. c) The diagonal of the effective area of the measuring field shall be at least 0,l mm and shall not exceed 5 Yo of the OUTPUT IMAGE diameter. d) If the luminance is measured
22、 through a lens with a one- or two-dimensional image detector in fixed position, the lens vignetting, the detector non-uniformity and the non-linearity of its response shall be corrected for. 5 Determination Of the LUMINANCE DISTRIBUTION and LUMINANCE NON-UNIFORMIM 5.1 Preparation a) The requirement
23、s for the measurement Set-up given in 4.1 shall be fulfilled. b) The TOTAL FILTRATION Of the RADIATION BEAM and the X-RAY TUBE VOLTAGE are adjusted according to 4.3 a) to obtain the required HALF-VALUE LAYER at the position corresponding to the CENTREOFTHE ENTRANCE FIELD according to 4.1. 5.2 Measur
24、ement 5.2.1 Measurement of the X-RAY FIELD uniformity a) After the determination Of the ENTRANCE PLANEand the CENTREOFTHE ENTRANCE FIELD, the XRII is removed from the X-RAY BEAM. No objects capable of scattering X-RADIATION shall remain in the X-RAY BEAM at a distance less than 50 cm from the ENTRAN
25、CE PLANE according to 4.1. Page 9 EN 61262-3 : 1994 b) The measurements of the uniformityshall be made with the effective area of the measuring device in the ENTRANCE PLANE and parallel to it but without the XRII in the beam. C) The AIR KERMA RATE is measured at those locations that correspond to th
26、e lOcatiOnS Of subsequent luminance measurements of the OUTPUT SCREEN. d) If the AIR KERMA RATE measurements at various locations are made at different time instances the X-RAY TUBE Output shall be monitored. 5.2.2 Measurement of the OUTPUT SCREEN luminance a) The XRII shall be positioned as stated
27、in 4.1. b) To measure the LUMINANCE DISTRIBUTION, the relative luminance of the OUTPUT SCREEN shall be measured along two orthogonal diameters of the OUTPUT SCREEN over a range covering at least 90 % of the corresponding ENTRANCE FIELD SIZE. The distances between successive points of measurements sh
28、all not be greater than those Corresponding to 10 % of the ENTRANCE FIELD SIZE. To measure the LUMINANCE NON-UNIFORMITY, the relative luminance of the OUTPUT SCREEN shall be measured at the CENTRE OF THE OUTPUT IMAGE and at four locations situated on two orthogonal diameters Of the OUTPUT SCREEN and
29、 with a distance from the CENTRE OF THE OUTPUT IMAGE that corresponds to 90 % Of the radius Of the.ENTRANCE FIELD. c) If the luminance measurements at various locations are made at different time instances the X-RAY TUBE output shall be monitored. NOTE - X-RAY TUBE output monitoring may be made also
30、 by monitoring the luminance of a fixed area of the OUTPUT SCREW. d) To correct the measured values of relative luminance for the non-uniformity of the X-RAY BEAM, the corresponding locations in the ENTRANCE PLANE and in the OUTPUT IMAGE shall be determined. e) The device for measuring the AIR KERMA
31、 RATE shall be removed. 5.3 Corrections If the measured values of relative luminance or relative AIR KERMA RATE at various locations correspond to different time instances, they shall be corrected for the temporal fluctuations of the incident AIR KERMA RATE 10 correspond to a temporally Constant inc
32、ident AIR KERMA RATE. if the incident X-RAY FIELD non-uniformity, determined according to 5.2.1, exceeds 2 % of the maximum RATE at the corresponding location in the ENTRANCE PLANE to correct for the spatial non-uniformity of the AIR KERMA RATE the relative luminance Value Of each location shall be
33、divided by the relative AIR KERMA X-RAY FIELD. CENELEC EN*hL262-3 94 = 3404583 OL4915b 287 = Page 10 EN 612623 : 1994 5.4 Determination The LUMINANCE NON-UNIFORMITY shall be computed as 4 =loo%x%x ZIL,-LJ lL, il where L, is the luminance at the CENTRE OF THE OUTPUT IMAGE, and Li (i = 1 to 4) are the
34、 luminances at the four points near the periphery of the OUTPUT IMAGE, according to 5.2.2 b). 6 Presentation of the results 6.1 PreSentafOn Of the LUMINANCE DISTRIBUTION a) The presentation Of the LUMINANCE DISTRIBUTION shall include the following: - XRII identification, e.g., generic type, model na
35、me or number. - The LUMINANCE DISTRIBUTION indicated by curves or by a table of numerical values showing the relative luminance as a function of distance along a diameter for one or two diameters through the OUTPUT IMAGE. The distances shall be scaled to correspond to distances in the ENTRANCE PLANE
36、. The relative luminance shall be given in per cent of the maximum value obtained. - The results presented shall cover a range of at least 90 % of the ENTRANCE FIELD SE. - If only one diameter is selected for stating the LUMINANCE DISTRIBUTION, it shall be the diameter showing the greatest variation
37、 of luminance in the OUTPUT IMAGE. b) Unless otherwise specified, the - ENTRANCE FIELD SIZE. 6.2 PfeSentfiOn Of the LUMINANCE NON-UNIFORMITY a) The presentation Of the LUMINANCE NON-UNIFORMITY shall include the following: - XRII identification, e.g., generic type, model name or number. - The LUMINAN
38、CE NON-UNIFORMITY as determined according to 5.4 and expressed in per cent. b) Unless otherwise specified, the - ENTRANCE FIELD SIZE. CENELEC EN*b12b2-3 94 3404583 0349357 313 = Page 11 EN 61262-3 : 1994 7 Statement of compliance a) If compliance with this standard for the determination of the LUMIN
39、ANCE DISTRIBUTION of an X- RAY IMAGE INTENSIFIER S to be stated, it shall be indicated as: - Luminance distribution: IEC 1262-3: 1994. b) If compliance with this standard for the determination of the LUMINANCE NON-UNIFORMITY ofan XRII is to be stated, it shall be indicated as: - Luminance non-unifor
40、mity .) IEC 1262-3: 1994. I Numerical value Of the LUMINANCE NON-UNIFORMITY. CENELEC ENxb12b2-3 94 3404583 0149158 05T m Page 12 EN 61262-3 : 1994 Annex A (informative) Terminology . Index of terms IEC788 rm. . rm. . Derived term without definition . rm. . + Term without definition rm. Name of earli
41、er unit rm. Shortened term . rm. . 5 Subclause 3.1 of IEC 1262-3 (present publication) 3.1. Name of unit in the International System SI . ACCOMPANYING DOCUMENTS rm-82-01 AIR ERMA RATE rm-13-11 and rm-13-13 ATENUATIONRATIO rm-13-40 ADDEDFILTER rm-35-02 ANTI-SCATER GRID . rm-32-06 BEAM LIMITING DEVICE
42、 . rm-37-28 CENTRE OF THE ENTRANCE FIELD . 3.1.7 CENTRE OF THE OUTPUT IMAGE 3.1.6 CENInALAXIS 3.1.8 DIAPHRAGM rm-37-29 ELECTRO-OPTICAL X-RAY IMAGE INTENSIFIER ENTRANCE FIELD . 3.1.3 ENTRANCE FIELD SIZE . 3.1.4 ENTRANCEPLANE 3.1.2 rm-32-40 FOCALSPOT . rm-20-13s HALF-VALUE LAYER . rm-13-42 LUMINANCE D
43、ISTRIBUTION . rm-32-45 LUMINANCE NON-UNIFORMIW 3.1.9 NON-SCREEN FILM rm-32-35 NORMAL USE . rm-82-04 OUTPUTIMAGE rm-32-49 OUTPUTSCREEN . rm-32-48 RADIATIONBEAM . rm-37-05 RADIATIONSOURCE . rm-20-01 SOURCE TO ENTRANCE PLANE DISTANCE . 3.1.5 TESTDEVICE . rm-71-04 TOTAL FILTRATION rm-13-48 CENELEC EN*bL
44、262-3 94 = 340q.583 0349359 T96 m Page 13 EN 61262-3 : 1994 X-IRRADIATION X-RADIATION . X-RAYEQUIPME NT X-RAYFIELD X-RAYB EAM X-RAY IMAGE INTENSIFIER . X-RAYPATERN . X-RAYSOURCEASSEMBLY X-RAYTUBE X-RAYTUBEVOLTAGE . XRII . rm-lZ-O9+ rm-ll-01- rm-37u5+ rm-20-20 rm-37-07+ rm-32-39 rm-32-01 m-2005+ rm-2
45、2-03 rm-36-02 3.1.1 CENELEC EN*bl12b2-3 94 = 3404583 OL49LbO 708 Page 14 EN 61262-3 : 1994 Annex ZA (normative) Other international publications quoted in this standard with the references of the relevant European publications This European Standard incorporates by dated or undated reference, provis
46、ions from other publications. These normative references are cited at the appropriate places in the text and the publications are listed hereafter. For dated references, subsequent amendments to or revisions of any of these publications apply to this European Standard only when incorporated in it by
47、 amendment or revision. For undated references the latest edition of the publication referred to applies. NOTE. When the international publication has been modified by CENELEC common modifications, indicated by (mod), the relevant EN/HD applies. IEC publication Date Title EN/HD Date 788 1984 Medical
48、 radiology - 2Ermzinology HD 501 S1 1988 CENELEC EN161262-3 94 W 3404583 OL4iLbL 644 W BS EN 61262-3 : 1995 List of references See national foreword. BS EN 61262-3 : 1995 IEC 1262-3 : 1994 BSI 389 Chiswick High Road London W4 4AL 9503- 7- 0.5k-RTL BSI - British Standards Institution BSI is the indep
49、endent national body responsible for preparing British Standards. It presents the UK view on standards in Europe and at the international level. It is incorporated by Royal Charter. Contract requirements 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. Revisions British Standards are updated by amendment or revision. Users of British Standards should make sure that they possess the latest amendments or editions. Any person who finds an inaccuracy or ambiguit
