A label-like device intended to be attached to a blood bag prior to ionizing-radiation (e.g., gamma, X-ray) blood irradiation to verify the type and broad dosage of radiation delivered to the blood. Blood irradiation is a technique designed to inactivate donor lymphocytes and help prevent transfusion-associated graft-versus-host disease. The label is specific to a type of radiation and typically includes a permanent colour-change indicator for dosage, and areas for recording other related data. This is a single-use device.