The requirement is that the gamma dose should fall within the upper 10 kGy of the dose range specification. However, many sterilization facilities have a regular dose window of 15 kGy. An acceptable option is then to allow the outcome to fall within 10 kGy from the upper specification limit, but also allow it to exceed the upper limit by ≤5 kGy (e.g. 40–55 kGy if the maximum-allowed dose is 40–50 kGy).
An alternative approach is to use a gamma irradiator that has a tighter dose range, such as those typically used for dose audits and validations.