1、 STDSBSI BS EN bL303-ENGL 1577 E Lb24bb9 Ob2LLbU 5b4 E BRITISH STANDARD Medical electrical equipment - Radionuclide calibrators - Particular methods for describing performance “he European Standard EN 61303 : 1995 has the status of a British Standard ICs 11.040.50 NO COPYING WITHOUT BSI PERMISSION E
2、XCEPT AS PERMITTED BY COPYRIGHT LAW BS EN 61303 : 1997 IEC 1303 : 1994 STD-BSI BS EN bI303-ENGL I777 Lb24bb9 ObZLLbL 4TO AmdNo. Date BS EN 61303 : 1997 Text affected This British Standard, having been prepared under the direction of the Health and Environment Sector Board, was published under the au
3、thority of the Standards Board and comes into effect on 15 June 1997 O BSI 1997 The following BSI references relate to the work on this standard Committee reference: CW82 Draft for cornent: 94/!504063 DC ISBN O 580 27630 9 Committees responsible for this British Standard The preparation of this Brit
4、ish Standard was entrusted by Technid Committee CW82, Nuclear medicine instrumentation, upon which the foilowing bodies were represent n is the number of measurements; is the mean. The coefficient of variation at each ACTIVITY level shall be stated. * * Ln Temperanire “C 10 15 20 25 30 35 40 Page 11
5、 EN 61303 : 1996 Pre8SUf9 kPa 106 104 102 100 98 96 94 6 Measurement Of AIR-DENSITY CHARACTERISTIC This test is not applicable to seaied IONIZATION CHAMBERS. This test shall be made at least for the reference device. NOTE - The density of the gas in the sensitive volume of He IONIZATION CHAMBER dete
6、rmines the current output for a given ACTIVITY of a given RADIONUCLIDE. For unsealed IONIZATION CHAMBERS. the density of air filling depends on the ambient atmospheric temperature and pressure. It is necessary, therefore, to determine the effect of air temperature and pressure on the IONIZATION CHAM
7、BER response. 6.1 Test method The device shall be placed in an environmental chamber in which the temperature and pressure may be varied independently over a range of at least +10 OC to +40 OC and 106 kPa to 94 kPa. A RADIOACTIVE SOURCE shail be placed in the device and the tem- perature set at +10
8、“C and the pressure at 106 kPa. Sufficient time shall be allowed to elapse to ensure that the temperature and pressure of the air in the device is in equilibrium with those in the environmental chamber. A series of measurements shall be taken and the standard deviation of the mean of the measure- me
9、nts stated. This procedure shall be repeated at the following temperatures and pressures. Since the AIR-DENSITY CHARACTERISTIC is also gamma-ray energy dependent, the procedures above shall be performed for a range of RADIONUCLIDES of differing principal amma-ray ener ies. The test shall be applied
10、using the following RADIONUCLIDES: 241Am, Co, l3Cs and 8 Co. 1251 is also recommended. 6.2 Evaluation The measurements shall be corrected for background and decay. A reference tem- perature, To, of 20 “C and a reference pressure, Po, of 100 kPa shall be used. For each RADIONUCLIDE and for each measu
11、rement with given environmental conditions, the following values shall be calculated: YT,p = mean of the measurements at temperature Tand pressure P 273 + T . - PO ET*p = 273 + To P For each RADIONUCLIDE, the values YT,p and shall be plotted on a linear graph with YT,p as the y-coordinate and shall
12、be determined. The AIR-DENSITY CHARACTERISTIC shaH then be obtained Ob! determining the ratio of YTSp to YT ,p . This characteristic shall be stated. as the x-coordinate. From the curve, the value of VT , O0 _ STD-BSI BS EN bL303-ENGL 1777 1b24bb7 Ob21174 057 Page 12 EN 61303 : 1995 7 Measurement Of
13、 SAMPLE VOLUME CHARACTERISTIC For each reference device, the tests in 7.1 shall be performed for each RADIONUCLIDE and for each sample container for which calibration figures are provided. As a secondary test method, the manufacturer shall measure SAMPLE VOLUME CHARAC- TERISTICS of a subset of RADIO
14、NUCLIDES on selected samples of each production lot of a given model. The subset of RADIONUCLIDES shall include sources of high, medium and low energy ranges. The subset of RADIONUCLIDES and the production samples to be tested shall be chosen by the manufacturer in such a way that the manufacturer c
15、an guarantee the volume characteristics of an individual device. 7.1 Test method A radioactive solution shall be introduced into the sample container for which calibration figures are provided. The volume of the solution shall be one-tenth of the maximum volume that can be accommodated in the contai
16、ner. The container shall be introduced into the measurement position of the device and measurements taken. The standard deviation of the mean of these measurements, after correction for background and decay, shall be stated. The volume shall also be stated. A volume of inactive solutibn shall then b
17、e added to the sample container. This volume shall be one-tenth of the maximum volume that may be accommodated in the container. The inactive solution shall be of the same chemical form and density as the radioactive solution. Measurements shall be taken at the same position as before. This procedur
18、e shall be repeated until the maximum has been reached. 7.2 Evaluation The values Y, (measurement value at volume V) shall be plotted against V on a linear- linear graph with Y” as the y-coordinate and V as the x-coordinate. From the fitted curve, the value of Y at the REFERENCE VOLUME, Vo, shall be
19、 determined, Vo being the volume at which the system accuracy is determined (see 3.1). The SAMPLE VOLUME CHARACTERISTlC shall then be obtained by determining the ratios of Y, to Yvo VO 8 Measurement of background response Tests to determine the inherent background response and the response to a know
20、n radiation field shall be performed for each reference device. As a secondary test pro- cedure, these tests shall be done for periodically selected samples of each production lot of a given model. The sample selection shalt be done in such a way that the manufacturer can guarantee the inherent back
21、ground response and the response to a known radiation field for each individual device. 8.1 The device shall be placed in an area where the radiation level is less than 0,2 (ISv/h. The RADiONUCLIDE FACTOR for 137Cs shall be applied. Any background offset facility shall be Set for no correction. A se
22、ries of measurements shall be made. The mean value shall be recorded. The standard deviation of the mean of the measurements shall be stated. inherent background response - Test method * * u) STDmBSI BS EN b1303-ENGL 1777 Lb24bb7 Clb21175 T75 Page 13 EN 61303 : 1995 8.2 Background response to known
23、radiation field - Test method A source of at least 2 MBq of 13Cs shall be placed at a horizontal distance of 1 m from the vertical axis of the IONIZATION CHAMBER. The vertical position shall be at the same be applied and any background offset facility shall be set to no correction. A series of at le
24、ast 10 measurements shall be made and corrected for background. The mean value together with its standard deviation shall be stated and expressed as observed ACTIVITY per MBq. height as the Centre Of the IONIZATION CHAMBER. The RADIONUCLIDE FACTOR for l3CS shall 9 Measurement of long-term reproducib
25、ility For each reference device the measurement of long-term reproducibility shall be done according to 9.1. As a secondary test, the measurement of long-term reproducibility shall be done for periodically selected samples of each production lot of a given model. The sample selection shall be done i
26、n such a way that the manufacturer can guarantee the long- term reproducibility of each individual device. 9.1 Method for measurements of long-term reproducibility The IONIZATION CHAMBER TEST SOURCE shall be placed in the specified position in the IONlATION CHAMBER and the specified RADIONUCLIDE FAC
27、TOR shall be applied. A Series Of at Least 10 measurements shall be taken at approximately equal time intervals over a period of at least one month. For each measurement, a sufficient number of readings shall be taken to obtain an appro- priate precision of the mean value. For each measurement, the
28、mean value of the repeated readings shall be recorded together with the time at which the measurements were taken. From these data, long-term reproducibility shall be reported as the coefficient of variation of the mean values (see 5.3). 10 Measurement of shielding performance Where an IoNiziNG RADI
29、ATION SHIELD is available as an option for the IONIZATION CHAMBER. the following tests shall be performed: - measurement of INSTRUMENT ACCURACY (see clause 3); - measurement of background response (see clause 8); - measurement of long-term reproducibility (see clause 9). These tests shall be perform
30、ed for 13Cs only with and without the shielding in place. Any effect on the RADIONUCLIDE FACTOR shall be stated. STD*BSI BS EN b1303-ENGL 1777 9 Lb2Libb7 Ob2117b 721 Page 14 EN 61303 : 1996 11 ACCOMPANYING DOCUMENTS and deClar8tiOn of performance A document shall accompany each RADIONUCLIDE CALIBRAT
31、OR which includes the f0llOWing information: 11.1 11.2 11.3 11.4 11.5 11.6 11.7 11.8 11.9 11-10 11.11 11.12 11.13 11.14 11.15 Nature and pressure Of gas filling Of IONIZATION CHAMBER Dimensions of IONIZATION CHAMBER well Dimensions of source holders Nature and thickness of shielding The maximum devi
32、ation for each parameter tested between a reference and an individual device shall be determined and stated RADIONUCLIDE FACTORS and INSTRUMENT ACCURACIES for each RADIONUCLIDE and for each sample container for the REFERENCE VOLUME (with and without shielding, if optional) as obtained by the refevan
33、t test method (3.1 or 3.2) Maximum ACTIVITY for which the instrument is calibrated and the corresponding activity Of 99mT at the REFERENCE VOLUME System reproducibility over the full range of ACTIVITY values available from the IONIZATION CHAMBER SYSTEM LINEARITY reported in ACTIVITY UnitS AIR-DENSIT
34、Y CHARACTERISTIC (for unsealed chambers Only) SAMPLE VOLUME CHARAcTERisTics for each sample container type and for each RADIONUCLIDE Inherent background response (with and without shielding, if optional) Background response as determined in 8.2 (with or without shielding, if optional) Long-term repr
35、oducibility and its reference date, at the IONIZATION CHAMBER TEST SOURCE RADIONUCLIDE FACTOR (with or without shielding, if Optional) RADIONUCLIDE Content Of the IONIZATION CHAMBER TEST SOURCE (including contaminants and their half-life) 11.16 Certificate stating test results obtained with a specif
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