Introductory Information: Reported to the NRC in 2017 this medical event relates to a patient treated with Y-90 TherasSphere to the liver for ablation therapy.
Error: The patient was administered 1.5 GBq of Y-90 microspheres (TheraSphere) to a 90 cc liver volume for ablation instead of the prescribed 0.629 GBq (17 mCi). The liver received 80,780 cGy (rad) instead of the prescribed 34,000 cGy (rad). The microspheres were administered to the patient too early, before they decayed to the prescribed activity. The cause was an error by a scheduling nurse who used the pretreatment plan rather than the final treatment plan. The physicist’s pre-treatment calculations and a preadministration time-out failed to identify the error. The physician was notified and contacted the patient. To prevent recurrence, the spreadsheet used to calculate patient dose was modified to include a check of the administration vial's calibration activity and date versus the prescribed activity and procedure date. The time-out procedure was also modified to confirm the proper activity prior to administration. Applicable personnel were trained on these changes.
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