IEC 60522-1:2020 pdf download – Medical electrical equipment – Diagnostic X-rays – Part 1: Determination of quality equivalent filtration and permanent filtration.
3 Terms and definitions For the purposes of this document, the terms and definitions given in IEC 60601 -1:2005, IEC 60601-1:2005/AMD1:2012, IEC 60601-1:2005/AMD2:2020, IEC 60601-1-3:2008, IEC 60601-1- 3:2008/AMD1:2013, IEC TR 60788:2004 and the following apply. ISO and IEC maintain terminological databases for use in standardization at the following addresses: • • IEC Electropedia: available at http://www.electropedia.org/ ISO Online browsing platform: available at http://www.iso.org/obp 3.1 FILTERING MATERIAL material between the X- RAY TUBE ASSEMBLY and the PATIENT which causes FILTRATION of the X- RAY BEAM 3.2 PERMANENT FILTRATION QUALITY EQUIVALENT FILTRATION effected in an X- RAY TUBE ASSEMBLY by permanently fixed materials intercepting the X- RAY BEAM , that are not intended to be removed for any application and are not provided with means for removal in NORMAL USE 3.3 QUALITY EQUIVALENT FILTRATION quantitative indication of the FILTRATION effected by one or several layer(s) of reference material(s) which, if substituted in a beam of specified RADIATION QUALITY under NARROW BEAM CONDITION for the material under consideration, give(s) the same RADIATION QUALITY as for the material under consideration Note 1 to entry: The QUALITY EQUIVALENT FILTRATION is expressed in suitable submultiples of the metre together with the reference material(s). Note 2 to entry: In this document, RADIATION QUALITY is characterized by its first HALF – VALUE LAYER . [SOURCE IEC 60601-1-3:2008, 3.52, modified – Addition of a new Note 2 to entry.]
4 Determination of QUALITY EQUIVALENT FILTRATION Alignment of X- RAY TUBE ASSEMBLIES and of the FILTERS 4.1 If, apart from the X- RAY TUBE ASSEMBLY under test, a reference X- RAY TUBE ASSEMBLY is used, then their REFERENCE AXES shall be aligned. NOTE The alignment of the REFERENCE AXES is important, as the HALF – VALUE LAYER depends strongly on the effective TARGET ANGLE . Simulations show, that at the typical mammographic HIGH VOLTAGE of 30 kV, the typical error in PERMANENT FILTRATION is of the order of 1,5 % per one-degree misalignment. At the typical radiographic HIGH VOLTAGE of 75 kV, it is of the order of 4 %. Unless otherwise stated, the FILTERS are positioned perpendicular to the REFERENCE AXIS . 4.2 Generation of the X- RAY BEAM for the determination The PERCENTAGE RIPPLE shall not be larger than 10 %. It is recommended to limit the PERCENTAGE RIPPLE to 4 %, in order to maintain accuracy,
– if the HIGH VOLTAGE is smaller than 50 kV, or – if the HIGH VOLTAGE is larger than 50 kV and if the atomic number of the FILTERS is larger than 30, or – if the HIGH VOLTAGE is larger than 50 kV and the atomic number of the FILTERS is not larger than 30, while the sum of the QUALITY EQUIVALENT FILTRATION of all materials with atomic number not larger than 26 is smaller than 0,5 mm Al. The HIGH VOLTAGE shall be kept constant during all the steps in the determination. NOTE Stability of the HIGH VOLTAGE during the determination is important, as the HALF – VALUE LAYER depends strongly on the HIGH VOLTAGE . H IGH VOLTAGE -shift of the order of 1 % in one of the steps of the determination can lead to an error in the determined value of the QUALITY EQUIVALENT FILTRATION of the order of 10 %. Unless other standards prescribe the HIGH VOLTAGE , the following values of the HIGH VOLTAGE are recommended: – for mammographic applications, 28 kV, – for dental applications, 60 kV, – for any other application, 75 kV, – unless the application does not include 75 kV or is centred outside 75 kV; then it is recommended to apply a HIGH VOLTAGE in the range of the application.