Four words that are never good to hear

"We've had a misadministration"

As a diagnostic medical physicist, you don't hear those words very often (unless you're talking to a therapy physicist), nor do you want to hear them very often. Not because something really really bad has happened, but mostly because it involves a lot of paperwork and calculating and almost always happen when you're in the middle of doing other things that need to be done yesterday.

Misadministrations in diagnostic radiology don't happen very often because, well, it's really hard for an event to qualify as one. Most of them tend to happen in Nuclear Medicine. 10 CFR Part 35 Subpart 3045 lists a bunch of criteria that have to be met in order for an event to be considered reportable (as far as the NRC is concerned).

10 CFR 35.3045 says (in part):

A licensee shall report any event, except for an event that results from patient intervention, in which the administration of byproduct material or radiation from byproduct material results in--
  • A dose that differs from the prescribed dose or dose that would have resulted from the prescribed dosage by more than 0.05 Sv (5 rem) effective dose equivalent, 0.5 Sv (50 rem) to an organ or tissue, or 0.5 Sv (50 rem) shallow dose equivalent to the skin; and
    • The total dose delivered differs from the prescribed dose by 20 percent or more;
    • The total dosage delivered differs from the prescribed dosage by 20 percent or more or falls outside the prescribed dosage range; or
    • The fractionated dose delivered differs from the prescribed dose, for a single fraction, by 50 percent or more.
  • A dose that exceeds 0.05 Sv (5 rem) effective dose equivalent, 0.5 Sv (50 rem) to an organ or tissue, or 0.5 Sv (50 rem) shallow dose equivalent to the skin from any of the following--
    • An administration of a wrong radioactive drug containing byproduct material;
    • An administration of a radioactive drug containing byproduct material by the wrong route of administration;
    • An administration of a dose or dosage to the wrong individual or human research subject;
    • An administration of a dose or dosage delivered by the wrong mode of treatment; or
    • A leaking sealed source.
  • A dose to the skin or an organ or tissue other than the treatment site that exceeds by 0.5 Sv (50 rem) to an organ or tissue and 50 percent or more of the dose expected from the administration defined in the written directive (excluding, for permanent implants, seeds that were implanted in the correct site but migrated outside the treatment site).

The radiation dose requirements (> 0.05 Sv (5 rem) effective dose equivalent, 0.5 Sv (50 rem) to an organ or tissue, or 0.5 Sv (50 rem) shallow dose equivalent to the skin) are almost always never met because diagnostic doses simply never get that high. The only procedure in Nuclear Medicine that comes close would be a therapeutic I-131 administration. There aren't any diagnostic radiology procedures that should come even close to these exposure levels. So unless that radiation dose threshold is met, even if the other criteria were met (wrong drug, wrong site, wrong patient, wrong dosage) it still wouldn't be considered a reportable event. It might still be considered a misadministration as far as internal hospital/departmental policies are concerned, but nothing that the NRC needs to be informed about. Still, that doesn't mean records don't need to be kept on the incident. And there are lots of things that need to be done: dose estimate calculations, physician notification, patient counselling, the paper trail, and plans to prevent recurrence. Usually it means getting lots of people involved. Fortunately for the patient though there usually aren't any significant side effects resulting from any misadministrations that happen in radiology. Radiation therapy misadministrations on the other hand, are a totally different matter.