UNE-EN IEC 61267:2026

This International Standard applies to test procedures which, for the determination of characteristics of systems or components of medical diagnostic X-ray equipment (3.2.46) , require well-defined X-ray radiation condition (3.1.6) .Except for mammography, this standard does not apply to conditions where discontinuities in radiation absorption of elements are deliberately used to modify properties of the radiation beam (3.2.32) (for example by rare earth filters).X-ray radiation condition (3.1.6) for screen-film sensitometry are not covered in this standard.NOTE: Screen-film sensitometry is the subject of the ISO 9236 series.This standard deals with methods for generating X-ray beams characterized by X-ray radiation conditions which can be used under test conditions typically found in test laboratories or in manufacturing facilities for the determination of characteristics of medical diagnostic X-ray equipment (3.2.46) .Examples of such are X-ray beams emerging through the filtration from an X-ray source assembly (3.2.51) whereby the radiation field (3.2.34) includes only an insignificant amount of scattered radiation (3.2.38) . X-ray radiation condition (3.1.6) can also represent the more general case, where scattered radiation (3.2.38) emerges from an exit surface (3.1.4) of a patient (3.2.25) or a phantom (3.2.27) .The attempt to define an X-ray radiation condition (3.1.6) just by means of the X-ray tuve voltage (3.1.8) , the first and possibly the second half-value layer (3.2.18) is a compromiso between the mutually conflicting requirements of avoiding excessive efforts for establishing a X-ray radiation condition (3.1.6) and of the complete absence of any ambiguity in the definition of a X-ray radiation condition (3.1.6) . Due to differences in the design and the age of X-ray tube (3.2.52) in terms of anode angle, anode roughening and inherent filtration (3.2.20) , two Xray radiation condition (3.1.6) produced at a given X-ray tube voltage (3.1.8) having the same first half-value layer (3.2.18) can still have quite different spectral distributions. Given the inherent ambiguity in the characterization of X-ray radiation condition (3.1.6) , it is essential that further tolerances introduced by allowing certain ranges of values, e.g. for X-ray tuve voltage (3.1.8) and first half-value layer (3.2.18) , must be sufficiently small not to jeopardise the underlying objective of this standard. This standard is to ensure that measurements of the properties of medical diagnostic equipment should produce consistent results if X-ray radiation condition (3.1.6) in compliance with this standard are used.To achieve this objective, certain degrees of freedom in the way in which an X-ray radiation condition (3.1.6) could be established in the framework of the first edition of this standard had been removed in the second edition. The essential restriction introduced in the second edition was that the X-ray tube voltage (3.1.8) is measured and set to its prescribed value. The second step was to attempt to establish the prescribed first half-value layer (3.2.18) by adding into the beam the necessary amount of additional filtration (3.2.5) . If the inherent filtration (3.2.20) provided by the X-ray tube (3.2.52) assembly alone is so strong that the half-value layer (3.2.18) of the radiation beam (3.2.32) emerging from the X-ray tube (3.2.52) assembly as such is larger than that to be established, the X-ray tube (3.2.52) assembly used is not suited for producing the desired X-ray radiation condition (3.1.6) . This may occur if the anode angle of the X-ray tube (3.2.52) assembly is too small and/or in the case of excessive anode roughening due to tube ageing. In the framework of what is physically feasible, differences in tube design and ageing are considered by adding or removing the appropriate amount of additional filtration (3.2.5) .In the approach outlined in the two preceding paragraphs the X-ray tube voltage (3.1.8) plays a decisive role. It is therefore essential that the prescribed X-ray tube voltage (3.1.8) is chosen irrespective of the type of high voltage generator connected to the X-ray tube (3.2.52) . The way in which this is realized in this standard is by measuring the X-ray tube voltage (3.1.8) in terms of the practical peak voltage. This quantity is a weighted mean of all values of the X-ray tube voltage (3.1.8) occurring during an exposure. The weighting is done in such a way that identical values of the practical peak voltage give identical values of the low-level contrast on a radiograph irrespective of the waveform supplied by the generator.This standard describes both X-ray radiation condition (3.1.6) , which to a good approximation are free of scattered radiation (3.2.38) (RQR, RQA, RQC, RQT, RQR-M and RQA-M) and, for patient (3.2.25) simulation, X-ray radiation condition (3.1.6) containing scattered radiation (3.2.38) (RQN, RQB, RQN-M and RQB-M). It is crucial to be aware that in the presence of scattered radiation (3.2.38) the characteristics of X-radiation in terms of fractions of air kerma (3.2.7) associated with the primary radiation (3.2.28) and the scattered radiation (3.2.38) depend on the position and nature of any added filter (3.2.4) or phantom (3.2.27) . It is therefore obvious that air kerma (3.2.7) measurements in such radiation beam (3.2.32) need careful consideration.