Patients who have undergone a nuclear imaging study with radioactive tracers become radiation emitters themselves--something people who come in close contact with those patients should be aware of, according to a research letter published May 7 in the Journal of the American College of Cardiology.
According to Thomas Hauser, M.D., senior author of the letter, the tracer--technetium-99--has a half-life of six hours, which means the radiation dissipates in a relatively short period of time.
"But if you are routinely very close to a patient who has had one of these studies, for a period of time shortly after the tracer has been injected, you could potentially get a radiation exposure that is not insignificant," Hauser told heartwire. "This came up because our echocardiography techs have sometimes been asked to do echocardiograms right after a [nuclear] stress test, and they were concerned about the radiation exposure."
Hauser and his colleagues measured radiation levels in 56 prospective patients who underwent myocardial perfusion imaging and determined that sonographers, for example, could receive a radiation dose as high as 0.16 mSv during a 24-minute echocardiogram, while a hospital transport worker might receive a dose equivalent of 0.02 mSv during a 10-minute patient transfer.
While these levels of exposure are low, according to Hauser, "when you have these repeated exposures over time, there might be an issue."
In the research letter, Hauser and colleagues said that while it was unlikely that exposure to post-myocardial perfusion imaging patients will exceed recommended limits in adults, close and repeated exposure to these patients should be avoided by individuals who are more radiosensitive, such as pregnant women and children.
Additionally, Hauser told heartwire that certain steps can be taken to reduce exposure to these patients, such as scheduling echocardiograms before rather than after nuclear tests, and making sure there is a minimum number of hours between tests. And, he said, if an echocardiogram is necessary right after a nuclear imaging study, healthcare providers should consider wearing a lead vest.