Determination of quality equivalent filtration and permanent filtration
IEC 60522-1-2020 pdf download.Medical electrical equipment — Diagnostic X-rays — Part 1: Determination of quality equivalent filtration and permanent filtration
Appareils électromedicaux — Rayonnements X de diagnostic — Partie 1: Determination de Ia filtration de qualité equivalenteet de Ia filtration permanente.
Steps for determining the QUALITY EQUIVALENT FILTRATION:
3a The reference X-RAY TUBE ASSEMBLY used produces an X-RAY BEAM which is filtered only by materials with atomic number not larger than 26, with a combined QUALITY EQUIVALENT FILTRATION of at least 0,5 mm Al. Its TARGET shall be of the same material as the TARGET of the X-RAY TUBE ASSEMBLY under test. Place the FILTER (F2), or (sub-)FILTER-stack (F2) to be measured in the X-RAY BEAM. Measure the AIR KERMA RATE 1( at a HIGH VOLTAGE under the conditions stated in 4.2, using a suitable RADIATION DETECTOR (D) as described in 4.3.
3b Using an iterative measurement process, determine the HALF-VALUE LAYER referenced to aluminium of the X-RAY BEAM by adding aluminium reference FILTERS (R) into the beam until the AIR KERMA RATE is one-half of the value determined in step 3a.
3c While maintaining the reference FILTERS (R) determined from step 3b in the beam, remove the FILTER (F2) or (sub-)stack (F2) and replace it with aluminium FILTER (Al) and measure the resulting AIR KERMA RATE 1(2. Using an iterative measurement process, adjust the total thickness of the FILTER (Al) such that in step 3d the AIR KERMA RATE is doubled. The resulting thickness of the FILTER (Al) represents the QUALITY EQUIVALENT FILTRATION of the FILTER (F2) or (sub-)stack (F2) under test (indicated by the dashed arrow in Figure 3).
3d Remove reference FILTERS (R) and compare the AIR KERMA RATE to the value determined in step 3c. The value at 3d shall be twice as large.
4.6 Determination of the QUALITY EQUIVALENT FILTRATION of a FILTERING MATERIAL or of a stack of FILTERING MATERIALS
4.6.1 Choice of TARGET ANGLE
Usually, the QUALITY EQUIVALENT FILTRATION depends on the RADIATION QUALITY, hence it depends also on TARGET ANGLE.
If the FILTERING MATERIAL is combined with just one X-RAY TUBE ASSEMBLY, it is recommended to perform the determination with an X-RAY TUBE ASSEMBLY with a TARGET with the same TARGET ANGLE.
If it is not known with which X-RAY TUBE ASSEMBLY the FILTERING MATERIAL will be used, then it is recommended to apply an X-RAY TUBE ASSEMBLY with a representative TARGET ANGLE such. that the deviation of the QUALITY EQUIVALENT FILTRATION over the typical range OF TARGET ANGLES in practical applications is minimized. For mammographic applications, this representative TARGET ANGLE is 10 or 11 • for applications above a HIGH VOLTAGE of 50 kV, this representative TARGET ANGLE is 100,11 , or 120.
4.6.2 Determination method
4.7 X-ray simulations
A software tool may be used to simulate the RADIATION QUALITY and to determine the QUALITY EQUIVALENT FILTRATION. If the method of simulation has been validated against the method described in this document over the full range of use, including consideration of K-edge issues, also a simulation can be used as base for a statement of compliance. The validated computed value of the QUALITY EQUIVALENT FILTRATION shall not be larger than the MEASURED VALUE. On request, the documentation of the method of validation and the results achieved shall be made available to USERS of the product documentation which includes the corresponding statement of compliance. It shall be stated that a computed value is provided.
4.8 Compliance test
Compliance with a stated value of PERMANENT FILTRATION or with a stated value of the QUALITY EQUIVALENT FILTRATION of a FILTERING MATERIAL is achieved if the MEASURED VALUE determined in the above tests is not less than the stated value and does not exceed the stated value by more than 30 %.
5 Indications and statements of QUALITY EQUIVALENT FILTRATION
5.1 PresentatIon of QUALITY EQUIVALENT FILTRATION values
The value of the QUALITY EQUIVALENT FILTRATION shall be expressed as the thickness in millimetres of the reference material aluminium, described by its chemical symbol.
QUALITY EQUIVALENT FILTRATION values should be presented with a maximum of one decimal place accuracy and a maximum of two significant figures.
NOTE The Indicated accuracy is in line with the limited accuracy 01 QUALITY EQUIVALENT FILTRATION determinations:
see IEC TR 60522-2 (2).
5.2 IndIcations and statements of PERMANENT FILTRATION
If an indication or statement of compliance for PERMANENT FILTRATION with this document is to be given, it shall take the applicable form, as given below as an example, which applies to a stated value of 1,2 mm aluminium determined at HIGH VOLTAGE of 75 kV:
a) for written statements, for example Ifl ACCOMPANYING DOCUMENTS:
PERMANENT FILTRATION 1,2 mm AI/75 kV IEC 60522-1:2020
b) for markings on the X-RAY TUBE ASSEMBLY:IEC 60522-1-2020 pdf download.