The following information was provided by the
Oregon Health Authority, Radiation Protection Services via email:
During preparation for a hepatic microsphere (ThereSphere) treatment, the oncology nurse primed the system but when the needle assembly was snapped into the dose vial a series of bubbles appeared. The nurse attempted to remove the bubbles from the tubing that was to be connected to the patient's catheter but was unsuccessful. The procedure physician was made aware of the bubbles and since the physician did not want to push them through the patient's catheter, the bubbled liquid was expelled into gauze which was subsequently added to the waste container. Working through this issue added approximately 10 minutes to the time between assay and administration.
In addition, the assayed activity of Y-90 was 96.5 percent of the prescribed dose of 440 Gy and 95.6 percent at time of administration after the 10-minute delay due to the bubbled liquid issue. Normally, 95-99 percent of the assayed activity is delivered to the target (liver), however, with the loss of activity through expelling bubbled liquid, the delivered activity dropped to 351.8 Gy which is greater than the 20 percent lower limit of 440 Gy (352 Gy) at 20.4 percent and makes this a reportable medical event.
[The physician notified the patient, documented this on the patient's chart, and stated there are no adverse effects from this under-dosing.] No additional dose is needed.
Cause and corrective actions:
It was stated the oncology nurse prepped the system 'correctly'. The licensee informed the TheraSphere representative regarding this issue with the needle assembly. At this time, we are unable to determine whether this event is considered human error or defective product.
It is worthy to note that if one of the two issues (delay of 10 minutes or starting with 96.5 percent) was absent, the under-dosing of greater than 20 percent probably would not have occurred.
Oregon Event Report Number: 22-0038
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.