A method of reducing radiation exposure of a non-cancerous tissue of a patient diagnosed with a cancer includes administering to the patient an agent capable of competing for binding sites on a surface of the non-cancerous tissue, provided that the administration is carried out after a waiting period that follows administration of a compound including a radionuclide to the patient, the compound having affinity for both a cancerous tissue and the non-cancerous tissue, and, further provided that the binding sites have an affinity for both the agent and the compound.