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The following report was received from the Vermont Department of Health via email: Medical Event: Y90 resin Sir-Spheres treatment infusion aborted due to kinked microcatheter. 99.5 (percent) of the drawn dose was not delivered to the treatment site. Contamination of IR (interventional radiology) suite floor detected. Contamination of infusion paraphernalia (gloves, shoe covers, gauze, towels) detected. Contaminated items were contained and floor was decontaminated to acceptable levels by RSO (Radiation Safety Officer). Date of Event: 11/18/2019 11/18/19 AU (Authorized User) notified referring physician and patient of the medical event 11/19/19 RSO contacted State of Vermont 11/19/19 NRC contacted for clarification of event 11/20/19 RSO contacted Sirtex Incident Details: Terumo Progreat, I.D. 0.027(inches) (0.7mm), 130cm length, was used initially to access treatment site. Boston Scientific, I.D. 0.021(inches) (0.5mm), 130cm length, was used to access treatment site after unsuccessful attempt with Progreat. IR (Interventional Radiologist) Fellow assembled the delivery device. The original dose measurement was 2.2 mR/hr at 1230 (EST). The Nalgene with undelivered dose vial and the second Nalgene with delivery catheter were measured in exactly the same setup as original dose measurement. The total residual in the 2 Nalgene containers were 1.9 mR/hr + 0.25 mR/hr = 2.15 mR/hr at 1430. With 2 hours decay correction, the Nalgene containers reading should be 2.15 x 1.02 = 2.19 mR/hr. 2.19 / 2.2 = 0.995 or 99.5 (percent) for Vial + Catheter. Therefore, about 0.5 (percent) of the drawn dose (44.3 mCi) was lost. 0.5 (percent) of 44.3 mCi is 0.2 mCi (This is the calculated amount of Y90 lost) The DAVYR (Dosimetry and Activity Visualizer for Y-90 Radioembolization) application provides the following liver dose calculation based on the partition model: Liver = 27.5 Gy for a 1.5 GBq (or 40.5 mCi) dose delivery. This is based on 100 (percent) of prescribed dose being delivered. In the worst-case scenario where all the lost activity (0.2 mCi) was delivered to the patient, the liver dose calculation is: Liver = 27.5 Gy x (0.2 mCi / 40.5 mCi) = 0.14 Gy (or 14 rem) The only way to properly measure the bags of contaminated paraphernalia (towels, gloves, gauze, shoe covers) in the same setup as the original dose measurement would involve transferring the contents into several Nalgene containers. This can be done next day to properly account for lost Y90 activity. Medical event criteria - the byproduct material administration has to meet the following (10 CFR 35.3045): 1. The dose differs from a dose that would have resulted from the prescribed dosage by more than 50 rem to an organ or tissue. The unintended dose to any organ or tissue from the lost 0.2 mCi Y90 would be similar to the Liver dose calculated above (14 rem) and does not exceed 50 rem difference. Note: The highest delivered dose to Liver from the lost Y90 is calculated to be 14 rem. This is below the target dose of 110 Gy (or 11,000 rem) and does exceed the 50 rem difference; however, this was a medical safety decision resulting from unforeseen microcatheter kinking due to patient anatomy. 2. The total dose delivered differs from the prescribed dose by 20 (percent) or more. Yes, the total dose delivered is calculated to be about 0.2 mCi and is much below the prescribed dose of 40.5 mCi. A medical safety decision to abort the infusion was due to an unforeseen device event (kinked microcatheter) that prevented the safe delivery of Y90 microspheres.

• * * UPDATE ON 11/26/19 AT 0738 EST FROM FRANCIS ONEILL TO OSSY FONT * * *

The following update was received from the Vermont Department of Health via email: As a follow up to Event Number 54408, Y-90 Sirsphere event, the calculated dose to the unintended organ, the pancreas, is 14 Rem or 0.14 Gray. Notified R1DO (Henrion) and NMSS Events Notification via email. A Medical Event may indicate potential problems in a medical facility's use of radioactive materials. It does not necessarily result in harm to the patient.