sham irradiation approximate sham irradiation Use approximate sham irradiation when at least one aspect of the irradiation (with the exception of the administration of the radiation exposure) is not followed precisely. For example, Not placing an organism or sample in a beam line for the same length of time as the irradiated organism(s) or sample(s) were left in the beam. Sham irradiation in which an identical irradiation protocol (with the exception of the administration of the radiation exposure) is not followed in every respect.