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The following information was received from the Washington State Department of Health: University of Washington broad scope license C001 reported a medical event. The event involves Y-90 microspheres contained in two vials of different activity. Vial A and Vial B were to be delivered to different treatment sites. However, the vials were mixed up and the lower activity vial was delivered to the wrong site, the Authorized User (AU) realized it was the wrong vial and did not inject the second vial. This resulted in an underdose of more than 20 percent. A full report is expected in 15 days and will be forwarded. 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.

• * * UPDATE ON 04/28/2021 AT 1321 EDT FROM TRISTAN DAY TO BRIAN P. SMITH * * *

The following update is from the report received via e-mail from the Washington State Department of Health: On Friday April 9, 2021, a patient had been prescribed two dosages of yttrium-90 microspheres intended for two different liver treatment sites. One treatment dosage was a larger amount than the other, 35.9 mCi and 21.4 mCi. Both dosages were measured in the Nuclear Medicine CRC 15R dose calibrator prior to use. They were found to be the correctly prescribed amounts and the vials were labelled correctly. Both dosages were transported to the Interventional Radiology suite. When the authorized user (AU) called for the first dosage, the higher of the two activities (35.9 mCi), it was set up and administered, including the required radiation dose rate measurement taken prior to and during the dosing. When the AU called for the second dosage (21.4 mCi), he noticed that the radiation dose rate measurement of the second dosage was higher than it had read for the first administration, which was supposed to be the larger of the two dosages. Realizing that the smaller of the two dosages was mistakenly administered first, the physician stopped the treatment and did not administer the second dosage. It was then confirmed that the patient received the lower of the two dosages (21.4 mCi) to the treatment site that was supposed to receive the higher dosage (35.9 mCi). Nuclear Medicine informed the Environmental Health and Safety Department's (EHS) Medical Health Physicist (MHP), and the MHP subsequently informed the Radiation Safety Officer (RSO). Initially, there were questions regarding the need to evaluate this event as a possible Medical Event. There was uncertainty regarding applying the medical event criteria to both sites together or to each individual site. Additionally, the first treatment site was under-dosed and the AU subsequently had determined that the dose delivered was adequate for that site. After discussing the event with the MHP on Monday morning, April 12, 2021, the RSO requested a meeting with Department of Health (DOH) to discuss the event. The MHP and RSO discussed the event with DOH that afternoon, and DOH informed that it would depend if the written directive included both sites, or if there was a written directive for each site. On Tuesday, April 13, 2021, all the required information was obtained, and the MHP and RSO reviewed the dosage and dose calculations and determined that the medical event criteria was met. The dose delivered is less than prescribed, and will result in no harm to the patient and it is the intention of the physician to treat the second site at some future time. Washington Event Report Number: WA-21-006

The following report was received from the State of Washington via email: On 4/21/2016, the Radiation Safety Officer at University of Washington reported by phone and by email that a Po-210 static ionization source was missing from a lab at the Southlake Union (SLU) Campus. The static ionization source had been placed in a cardboard box in preparation for shipment back to NRD (manufacturer). Someone in the lab thought the box was empty and placed it in the recycling. This was discovered on Monday, and the lab had been searching for it for a couple of days before notifying the Radiation Safety Officer. The immediate report value for Po-210 is 100 microCi and the 30 day report value is 1 microCi. Source information: Isotope: Po-210, Manufacturer: NRD, Model: P-2001, Initial Activity: 5 mCi (May 2015), Current Activity: approximately 1 mCi Device information: Nuclespot - Static Eliminator, Manufacturer: NRD, Model: P-2042-1000, Serial Number: Not reported. The facilities personnel are currently trying to find out from (the recycling company) where the recycling is taken for processing. (The recycling company) picks up recycling from the SLU campus twice a week on Friday and Tuesday. University of Washington Principal Investigator lab informed NRD of the loss. Once their investigation is complete, UW will provide us (WA Office of Radiation Protection) with a written report as required by WAC 246-221-240(2). Incident Number: WA-16-018

• * * UPDATE AT 1541 EDT ON 09/18/16 FROM ANINE GRUMBLES TO S. SANDIN * * *

The following information was received from the State of Washington via email: WA-16-018 Po-210 static ionization source missing from University of Washington Update and Closure University of Washington submitted their final report on the lost Po-210 static eliminator. University of Washington is a Broad Scope A Licensee. Their (University of Washington) Radiation Safety staff performed a thorough investigation and search for the source. There are a total of six possible routes the source may have taken; all of which end up overseas. Initially, three potential avenues were explored at Recology CleanScapes:

1. If source stayed inside the box with the paper - processed as corrugated cardboard and sent overseas for recycling processing 2. If paper came out of the box and source stayed with paper - processed as mixed paper and sent overseas for recycling process 3. If paper came out of box and source came out of the paper - source would have filtered out into glass recycling stream (includes metal), which is sent to Strategic Materials. The RSO contacted Strategic Materials and identified an additional three possible outcomes for the source, if it made it to the Strategic Materials facility. 4. All incoming material is first passed by a large magnet, if the source housing was ferrous enough the source would have been transferred to a metal recycler. The source model is believed to have an aluminum housing. 5. If the source was not pulled out by the magnet, it was either manually removed by a picker and thrown in the trash, or 6. The source was pulled out by an Eddy Current device and would be in one of the device collection bins. This also would have been thrown in the trash. Staff at both facilities were shown photos of the source and interviewed, and no one had seen or moved the source. Ultimately, it is believed that the source, thoroughly wrapped in in paper, in a corrugated box was processed and sent overseas in a bulk cardboard or mixed paper recycle bundle. The Registry of Radioactive Sealed Sources and Devices - Safety Evaluation of Device (Number: NY 502 D 108 G) for the P-2042 model indicates an maximum external exposure rate of 0.05 mR/hr on contact with the source. This is equivalent to background radiation levels. It should be noted that the principle emission of Po-210 is an alpha particle, so the exposure falls off rapidly with increasing distance from the source. Therefore, the exposure to any individual handling the source would be negligible. Since Po-210 is an alpha emitter, the highest risk would be to a person who ate the radioactive foil. However, this scenario is extremely unlikely due to the fact that the individual would have to first remove the foil from the housing, and then have a desire to eat the foil. Some new additions to the information: Manufacturer: NRD Inc. Device Type: Nuclespot - Static Eliminator Device Model: P-2042-1000 Sealed Source Model Designation: P-2001 Serial Number: A2KG893 NRD Lease Number: 059345 Shipped to UW: 5/21/2015 Original Activity: 5 millicuries Activity when lost: 1 millicurie This source is considered lost and unrecoverable. The assessed health and safety risk is very low. This incident is considered CLOSED. Notified R4DO (Miller) and NMSS Events Notification via email. THIS MATERIAL EVENT CONTAINS A "LESS THAN CAT 3" LEVEL OF RADIOACTIVE MATERIAL Sources that are "Less than IAEA Category 3 sources," are either sources that are very unlikely to cause permanent injury to individuals or contain a very small amount of radioactive material that would not cause any permanent injury. Some of these sources, such as moisture density gauges or thickness gauges that are Category 4, the amount of unshielded radioactive material, if not safely managed or securely protected, could possibly - although it is unlikely - temporarily injure someone who handled it or were otherwise in contact with it, or who were close to it for a period of many weeks. For additional information go to http://www-pub.iaea.org/MTCD/publications/PDF/Pub1227_web.pdf

The following information was provided via e-mail from the Washington State Department of Health, Office of Radiation Protection: A Nuclear Medicine technologist received an overexposure to her extremity dosimeter for March 2011 while working in the basement of the Magnusen Health Sciences Building on the UW Campus. The Extremity Dose was reported as 56,440 mrem. During the month of March, she performed several cell-labeling procedures involving 75mCi, 111mCi, and 108mCi amounts of Y-90. There were also several labeling procedures involving the use of I-131 during the same time frame. However, because the whole body badge showed no significant exposure, it is believed the majority of the exposure came from the technologist's work with Y-90. Licensee: University of Washington City and State: Seattle, WA License Number: WN-C001-1 Type of License: Broad A Date and time of Event: March 1 - March 30, 2011 Location of Event: UW Magnusen Health Sciences Building Investigation is ongoing. Washington Report #WA-11-030

• * * UPDATE ON 7/19/11 AT 1330 EDT TO HUFFMAN FROM THE STATE OF WASHINGTON VIA E-MAIL * * *

On 6 June 2011, the department (Washington Division of Radiation Protection) received notification via letter from the University of Washington (UW) that an employee, had received an extremity dose to the left hand of 56,440 mrem from Yttrium 90 for the month of March 2011. The department (Washington Division of Radiation Protection) was notified that the employee retired in May 2011. An incident number WA-11-030 was assigned to the event. UW informed the technician of the overexposure and she agreed to meet to discuss the incident. On 15 June 2011, a Health Physicist from the Department of Health met with the UW RSO, a UW Health Physicist, and the technician to discuss the incident. The Y-90 comes in bulk and must be divided into smaller aliquots based on the desired dose for cell labeling. These aliquots must be handled several times during the cell labeling procedure by the technician. The small size of the aliquot tubes made it too difficult to use tongs or other devices that might have lessened their exposure during these parts of the procedures. Most of this work was done in a hood behind shielding so that the whole body dose remained normal. Because the technician is right-handed, she would most often hold the tube containing the Y-90 in the left hand so she could use their right hand to add reagents or pipette the Y-90 solution into another tube. Although the exposure to the right hand did not exceed the annual limit, it was also unusually high for the month of March, 10.85 REM. The technician stated that there was no spill or other unusual occurrence during the month of March. It is highly unusual to do multiple labeling procedures in a one month period and March 2011 is the only time she has done three in one month. The amounts received, 75mCi, 111mCi, and 108 mCi were also larger than average. There were also several procedures involving the use of large doses, up to 1 Ci, of I-131 in March. However, this was not out of the ordinary for the technician so it is believed to be more likely that the multiple labeling procedures involving Y-90 contributed to exceeding the annual exposure limit to the left hand. Although, the technician is required to do surveys of the lab, the lab only has access to a GM detector and the area readings in the lab are often higher than background because of the large quantities of nuclides on hand. It is difficult for the technician to determine if contamination exists because of these high area readings. No swipe surveys are done by the technician. Swipe surveys are done by the radiation safety office staff. The last survey in which swipes were taken was January 2011. No contamination was noted at that time. The dose reconstruction was done to verify that the technician could in fact have received the reported dose given the time frame the technician was working with the Y-90. The dose reconstruction was also done to eliminate the possibility that the dose recorded by the ring dosimeter could have been caused by the ring being contaminated by Y-90 and that contamination remaining on the dosimeter. It was concluded by the UW RSO and the department (Washington Division of Radiation Protection) that handling these amounts of Y-90 could result in a dose of 56.4 REM in a very short period of time. Therefore, it is the conclusion of this investigation that the reported exposure is real. As a result of this investigation, the technician has been informed that she cannot work in an environment which would further contribute to her 2011 radiation dose. Because she is retired and no longer employed as a radiation worker at any facility, this should not be a hardship. It was determined that although the technician received an exposure above the legal limit, it is unlikely to result in any adverse health effects and no medical intervention is warranted. The Y-90 labeling has been halted at UW. No other person has done a labeling of this kind since the technician's retirement. No further work of this kind will take place at UW until a complete reworking of the procedures is completed and submitted to the Department, and their own RSC, for approval. This incident is closed. R4DO (Campbell) and FSME EO (Zelac) have been notified.