This document is applicable to X-RAY SOURCE ASSEMBLIES and X-RAY TUBE ASSEMBLIES.

NOTE 1 If, for certain MEDICAL ELECTRICAL SYSTEMS, special radiation fields are required such that the scope of IEC 60806 does not apply (e. g., using CT collimators with bow-tie filters), the appropriate system particular standard applies.

This document specifies a method for the determination of the greatest geometrically symmetrical RADIATION FIELD at a specified distance from the FOCAL SPOT for which the percentage AIR KERMA RATE along the major axes of the RADIATION FIELD does not fall below a permitted value.

NOTE 2 In practical use AIR KERMA or AIR KERMA RATE are the most practical physical measures to quantify X-RAY PATTERNS.

In case multiple FOCAL SPOTS are not super-imposed, each FOCAL SPOT has its own REFERENCE AXIS. Then the maximum RADIATION FIELD can be given for each FOCAL SPOT separately.

NOTE 3 The maximum symmetrical RADIATION FIELD can change from its initial value as the X RAY TUBE ages through use.