1、STD.BSI BS EN 12544-2-ENGL 2UU 81 Lb24bb 085448b 8T8 BRITISH STANDARD Non-destructive testing - Measurement and evaluation of the X-ray tube voltage - Part 2: Constancy check by the thick filter method The European Standard EN 12544-2:2000 has the status of a British Standard ICs 19.100 BS EN 12544-
2、2:ZOOO NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMTED BY COPYRIGHT LAW National foreword direction of the Engineering AmdNo. Date Sector Committee, was published under the authority of the Standards Committee and comes into effect on 15 June 2000 This British Standard is the official English la
3、nguage version of EN 1254422000. The UK participation in its preparation was entnisted to Technical Committee WEW46, Nondestructive testing, which has the responsibility to: Comments - aid enquirers to understand the text; - present to the responsible European committee any enquiries on the - monito
4、r related international and European developments and promulgate interpretation, or proposals for change, and keep the UK interests informed; them in the UK. A list of organizations represented on this committee can be obtained on request to its secretary. Cross-references The British Standards whic
5、h implement international or European publications referred to in this document may be found in the BSI Standards Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Find” facility of the BSI Standards Electronic Catalogue. A British Standard does no
6、t purport to include ail 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 legal obligations. Summary of pages This document comprises a front cover, an inside f
7、ront cover, the EN title page, pages 2 to 9 and a back cover. The BSI copyright notice displayed in this document indicates when the document was last issued. O BSI 06-2000 ISBN O 580 34178 X STD*BSI BS EN L25q4-2-ENGL 2000 8 Lb2Vbb7 OBSiidd b70 EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 1
8、25442 February 2000 _ ICs 19.100 English version Non-destructive testing - Measurement and evaluation of the X-ray tube voltage - Part 2: Constancy check by the thick filter method Essais non destructifs - Mesurage et valuation de la tension des tubes radiognes - Partie 2: Contrle de la constance se
9、lon la mthode du filtre pais Zerstrungsfreie Prfung - Messung und Auswertung der Rntgenrhrenspannung - Teil 2: Konstanzprfung mit dem Dickfilter-Verfahren This European Standard was approved by CEN on 24 December 1999. CEN members are bound to comply with the CENKENELEC Internal Regulations which st
10、ipulate the conditions for giving this Europsan Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning ruch national standards may be obtained on application to the Central Secretariat or to any CEN member. This European Standard
11、 exists in three official versions (English, French, German). A version in any other language made by traislation under the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as he official versions. CEN members are the national standards
12、 bodies of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORM
13、UNG Central Secretariat: rue de Stassart, 36 B-1050 Brussels O 2000 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 12544-2:2000 E Page 2 EN 12544-2:2000 Contents Foreword . 3 Introduction . 4 1 Scope . 5 2 Principle and equipment
14、5 3 Measurement . 7 4 Test report 8 Annex A (informative) Example for application 9 O BSI 06-2000 STD-BSI BS EN 12544-2-ENGL 2000 Lb24bb7 0851470 227 Page 3 EN 12544-212000 Foreword This European Standard has been prepared by Technical Committee CEN/TC 138, Non-destructive testing, the secretariat o
15、f which is held by AFNOR. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by August 2000, and conflicting national standards shall be withdrawn at the latest by August 2000. According to the CENKENEL
16、EC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Swit
17、zerland and the United Kingdom. In the framework of its scope, Technical Committee CEN/TC 138 entrusted CENTTC 138MIG 1 “Ionizing Radiation“ with preparing the following standard: EN 12544-2, Non-destructive testing - Measuremenent and evaluation of the X-ray tube voltage - Part 2: Constancy check b
18、y the thick filter method. EN 12544-2 is a pari of series of European Standards; the other parts are the following: EN 12544-1, Non-destructive testing - Measurement and evaluation of the X-ray tube voltage - Part 1: Voltage divider method. EN 12544-3, Non-destructive testing - Measurement and evalu
19、ation of the X-ray tube voltage - Part 3: Spectrometric method. O BSI 06-2000 Page 4 EN 12544-2:2000 Introduction In order to cover the different requirements for the measurement of the X-ray tube voltage, three different methods are described in EN 12544-1 to EN 12544-3. The voltage divider method
20、(EN 12544-1) enables a direct and absolute measurement of the average high voltage of constant potential X-ray systems on the secondary side of the high voltage generator. The thick filter method (EN 12544-2) describes a constancy check. This method is recommended for the regular stability check of
21、an X-ray system. The spectrometric method (EN 12544-3) is a procedure for non-invasive measurement of the X-ray tube voltage using the energy spectrum of the X-rays. This method can be applied for all X-ray systems and shall be applied whenever the voltage divider method is not applicable, e.g. in c
22、ase of tank units where it is not possible to connect the voltage divider device. O BSI 06-2000 SD-BSI BS EN L25qq-Z-ENGL 2000 Lb2ibbS 0854472 OTL Page 5 EN 12544-2:2000 1 Scope This standard specifies a constancy check of a X-ray system where mainly the X-ray voltage is checked and also the tube cu
23、rrent and the constitution of the target which can be changing due to ageing of the tube. The thick filter method is based on a measurement of the dose rate behind a defined thick filter using defined distances between the X-ray tube, the filter and the measuring device. This method is very sensitiv
24、e to changes of the voltage, but it does not provide an absolute value for the X-ray tube voltage. Therefore, a reference value is needed and, it is recommended to find this reference, for example, within the acceptance test of the system. The thick filter method is a rather simple technique and may
25、 be applied by the operator of an X-ray system to perform regularly a constancy check of the system. The method can also be applied for consistency checks after changing components which may affect the X-ray tube voltage. This method can be applied for all types of X-ray systems, .e. for constant po
26、tential, half wave and impulse wave generators with a tube current larger than 1 mA. 2 Principle and equipment The equipment to be used includes the following components, see Figure 1: - the X-ray system; - a specified collimator; - a specified filter; - - suitable dose meter or dose rate meter; a f
27、ilm for the prove of good collimation and dose meter or dose rate meter adjustment. 1 X-raytube 2 collimator 3 thickfilter 4 lead shield 5 film 6 dosemeter Figure 1 - Setup of the thick filter method O BSI 06-2000 STD.BS1 BS EN L254q-Z-ENGL 2000 E Lb24bb7 0854473 T38 Page 6 EN 12544-2:2000 It is pos
28、sible to apply any type of filter and distances. Two aspects are important: - To obtain reproducible values, the collimator, the filter and the dose rate meter shall be identical and, the focus to filter distance il2 and the focus to dose rate meter distance D, shall be fixed for the reference and a
29、ll subsequent measurements. - The filter material and thickness shall be selected according to Figure 2. The requirements concerning the dose meter or dose rate meter are: - The long term stability shall be 3 times better than the tolerance of the measured values. A regular stability check of the do
30、se rate meter, using a radioactive source, is necessary. The device shall have adequate measuring ranges. The exposure time shall be selected to obtain values between 50 % and 100 % of the scale. Three or more measurements shall be taken and the results shall be averaged. The diameter of the selecte
31、d collimator shall be as small as possible. The area of homogeneous radiation intensity at the dose meter or dose rate meter shall be equal or less then 3 times of the size of the detection chamber of the dose meter. This shall be proven with a film exposure due to the requirement of exact adjustmen
32、t. This radiograph marked with the date of measurement may be used for documentation. Figure 3 shows a typical radiograph of a dose meter which is well adjusted corresponding to Figure 1. NOTE The results of the measurement arrangement are reliable if it provides the same value in horizontal and ver
33、tical adjustment. - - Using the thick filter method, the measured values will change approximately 5 to 10 times faster (leverage factor) than the X-ray voltage changes. That means for example that 5 % of the X-ray tube voltage change corresponds to 25 % to 50 % of the measured dose rate. n E U a, I
34、A v) cn 0 c Y o c I- .- E t- E S .- 3 Tube Voltage kV Figure 2 - Minimum filter thickness values O BSI 06-2000 STD-BSI BS EN 12544-2-ENGL 2000 H Lb24bb9 0854474 774 H Page 7 EN 12544-2:2000 Figure 3 - Radiograph of the well-adjusted dose meter corresponding to Figure 1 3 Measurement In order to carr
35、y out the constancy check of an X-ray system or the consistency check of an X-ray system to compare different components the dose rate is measured using a filter as given in Figure 2 or thicker. 3.1 Leverage factor For the first application of the thick filter method the leverage factor i, shall be
36、determined corresponding to the selected setup. The dose value shall be measured at 100 % (boo) and at 95 % (Dgs) of the test voltage. NOTE The leverage factor should be adjusted between 6 and 8. This is a compromise which considers limitations in exposure time. A high leverage factor is recommended
37、 for high accuracy of the method. The leverage factor is calculated by equation (1) 3.2 Constancy check The constancy test of the tube shall be repeated regularly at the given voltage. The arrangement corresponding to Figure 1 shall be used with the same collimator, thick filter (thickness and mater
38、ial) and the same calibrated dose meter for the constancy check. The constancy of the tube voltage is confirmed if the measured dose value or dose rate value has been reproduced within the required tolerance T (in %)which is calcualted by equation (2). Within the reference measurement all essential
39、parameters (distances D1 and D2, filter material and thickness, type of dose meter or dose rate meter) shall be documented. The arrangement shall be identical for all subsequent measurements. An example is given in Annex A. O BSI 06-2000 STD-BSI BS EN 12544-2-ENGL 2000 lb24bb 0854495 800 I Page 8 EN
40、 12544-2:2000 4 Test report The test report of the measurements shall contain at least the following information: reference to this standard; X-ray system, type and fabrication number; the X-ray parameters: voltage (kv), current (mA) and the selected focus size, preferably the nomimal voltage and th
41、e maximum current; type and size of collimator; filter type and thickness, preferably with identification number; dose rate meter, or dose meter, also with identification number; focus to filter distance; focus to dose rate meter distance; drawing of the setup if it deviates from Figure 1; the measu
42、red value and the measured leverage factor; the date of the measurement; the deviation from the reference value; name and signature of operator. O BSI 06-2000 Page 9 EN 12544-2:2000 Annex A (informative) Example for application The usage of this standard needs exact adjustment and shielding. It is d
43、esigned for the application of inexpensive equipment. Some reference values are given for orientation of users in Table A.l. Due to deviations in the adjustment as well as the equipment, considerable differences to the given data are possible. The applied X-ray tube was of the constant potential typ
44、e. An usual pen-type dose meter was used for the measurements of the dose values. The absolute accuracy of the dose meter read out is expected to be not better than 20 %. Nevertheless, the final accuracy amounts to about 3 % if a leverage factor of 6,6 is presupposed. Table A.l - Parameter for thick
45、 filter method Tube Collimator Thick D95 Exposure L, voltage mm mm diameter filter mSv mSv mAmin EXAMPLE For a constancy check at 200 kV and the conditions described above (Table A.l) the Poo value should be always obtained between l,l mSv and 2,l mSv to prove a deviation within the tolerance of TI
46、5 %. O BSI 06-2000 BS EN 12544-2:2000 BSI 389 Chiswick High Road London w4 4AL STD-BSI BS EN 12594-2-ENGL 2000 I lb29bb9 0854977 b83 I BSI - British Standards Institution BSI is the independent national body responsible for preparing British Standards. It presents the UK view on standards in Europe
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