A 74-year-old woman with hyperthyroidism was referred for radioiodine therapy. The patient was accidentally given 60 mCi of Lu-PSMA orally instead of I. Upon discovery of this medical event, we immediately started radiation protective actions including hydration, antiemetics, and laxatives. The patients did not have any symptoms. Static acquisition was performed from the abdominal-pelvic and head and neck regions at 20 and 90 hours after ingestion, which showed prominent intestinal activity and mild systemic activity in the kidneys, bladder, salivary, and lacrimal glands.