In the U.S., the Nuclear Regulatory Commission (NRC) regulates the use of radioactive isotopes for the diagnosis and treatment of disease. To learn from mistakes and protect patients during medical procedures that use isotopes, the NRC began requiring hospitals to report isotope misadministration in 1980.
In 2002, the term misadministration was changed to “medical event” and the NRC established risk-based reporting limits of 500 millisieverts (mSv) to patient tissue. A sievert is a measure of radiation that includes the type and the amount of radiation absorbed in a certain mass. During a normal PET procedure, the radiation dose to the tissue of the average person is approximately two-thousandths of a sievert (2 millisieverts). The NRC concluded that when a patient unintentionally receives 500 millisieverts in a single irradiation, it should be reported as a medical event.
Nuclear medicine events reported to NRC are uncommon, but have included radioactive isotopes being spilled on patients, the wrong patient receiving radiation, and the wrong dose being injected. In the case of an infiltration, if just 10% of the injected dose for a typical PET imaging procedure infiltrates into one cubic centimeter of tissue, the radiation exposure to that tissue will be 1,500 times greater than if the dose had been injected cleanly. That would surpass the NRC reporting threshold by about six times.
Despite this risk, long-standing NRC policy specifically exempts hospitals from reporting any infiltrations. The consequence of this loophole is that the NRC — along with patients and physicians — have no idea of the true impact of infiltrations.
Read more by David Townsend at STAT
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