Patent ID: 8442179

Claim:
A method of tagging and subsequently verifying an identity of a target comprising: identifying the target; irradiating the identified target with an x-ray pulse to thereby create one or more radioisotope species within the target, wherein irradiating the identified target comprises controllably adjusting an energy level of the x-ray pulse with which the identified target is irradiated to create a unique radioisotope signature for the target; initially detecting radiation emitted by the target based upon the one or more radioisotope species created within the target so as to define the unique radioisotope signature for the target; identifying a time at which the radiation is initially detected; following initial detection of the radiation, subsequently detecting radiation emitted by an individual or an item and identifying a time at which the radiation is subsequently detected; determining an anticipated radioisotope signature based upon the unique radioisotope signature for the target and decay of the radioisotope species that were created within the target by said irradiating of the target during a period of time between initially detecting the radiation and subsequently detecting the radiation in accordance with predefined rates of decay for the respective radioisotope species; and comparing the radiation emitted by the individual or the item that was subsequently detected with the anticipated radioisotope signature to permit verification of the identity of the individual or the item as the target.