The NRC’s Office of Nuclear Reactor Regulation and Office of Nuclear Material Safety and Safety and Safeguards recently issued two Information Notices (INs) in response to medical events arising from the administration of radiopharmaceuticals.
The first IN alerts medical-use licensees to four strontium (Sr)-82/rubidium (Rb)-82 generator elution events that resulted in patients receiving concentrations of Sr-82 and Sr-85 in excess of regulatory requirements. The IN describes four separate events in which approximately 90 patients were administered Rb-82 chloride for cardiac imaging that contained Sr-82 and Sr-85 concentrations in excess of the regulatory limits identified in 10 CFR § 35.204. In evaluating these events, the NRC found that:
- Operators did not regularly perform breakthrough tests, and that their failure to do so caused several patients to receive doses in excess of the medical event criteria.
- Operators failed to switch the scale on the dose calibrator from millicuries to microcuries before measuring the decayed vial. Doing so masked the Sr-82 and Sr-85 breakthrough and led to multiple overexposures, though none in excess of the medical event criteria.
- An operator used Ringer’s lactate intravenous fluid instead of sterile saline as the eluent, causing patients to receive doses five to 10 times greater than the medical event criteria.
- An operator used Ringer’s lactate intravenous fluid instead of sterile saline as the eluent, although no patient received a dose in excess of the medical event criteria.
NRC attributed the overexposures to human error and failure to follow applicable procedures and stressed the need to heed all warnings associated with the use of Sr-82/Rb-82 generators and the performance of breakthrough tests.
The second IN identifies recent medical events involving the administration of Y-90 microspheres. These medical events resulted from a variety of causes, such as errors with the written directive, clogging and kinking in the catheters causing the administration of a reduced amount of microspheres to the patient, and treatment to the wrong part of the body.
Among the reported medical events were:
- Seven events involving dose or activity going to the target organ that exceeded the written directive by more than 20% as a result of human errors
- Twenty-seven events involving blockages of the microspheres in the delivery system either from kinks or dents in the catheter or clumping of the Y-90 microspheres in the catheter
- Eight events involving treatment to the wrong location covered by, among other things, administrative error
In evaluating these events, the NRC stressed the importance of: (1) having a signed and dated written directive as described in the Y-90 microsphere licensing guidance document; (2) reviewing the written directive before administering Y-90 microspheres; and (3) developing, implementing, and maintaining written procedures to provide high confidence that each administration is in accordance with the written directive.
Medical-use licensees are subject to NRC and agreement state inspections and enforcement actions, both of which may be time consuming and costly. We will continue to monitor and report issues related to medical uses of radioisotopes.