Treatments may set off security alarms

Here’s one more thing to worry about at national security checkpoints. The increasingly sensitive radiation detectors now used by transportation officials are more likely to be set off by patients treated with radioactive materials.

In newly released research, doctors have found that nuclear medicine therapies can remain in the body for up to three months. About 18 million nuclear medicine procedures were performed in the U.S. in 2002. The U.S. Department of Homeland Security estimates that 10,000 portable radiation detectors are used by guards at airports and other national ports of entry to prevent smuggling or illegal use of radioactive materials.

“Because of the widespread deployment of these extremely sensitive portable detectors among security personnel, we expect this to become a more common occurrence,” says Dr. Lionel Zuckier, the study’s lead author and a radiologist at the New Jersey Medical School-University of Medicine and Dentistry of New Jersey in Newark.

He and his colleagues tested several isotopes to gauge the maximum amount of time that could elapse before the lingering radiation would no longer set off detectors. They found that fluorine-188 used in PET scans is active only up to 24 hours; technetium-99, the radioactive tracer employed in kidney, liver, thyroid and bone scans, is active for three days; thallium used in cardiac exams stays in the body for up to 30 days; and iodine, which treats thyroid problems, triggered alarms up to 95 days later.

The Society of Nuclear Medicine and the U.S. Nuclear Regulatory Commission recommend hospitals develop an official letter or card that indicates what type of nuclear medicine procedure a patient received, and whom to call at the hospital for verification. Without a doctor’s note, says Zuckier, nuclear medicine patients should anticipate longer waits at security checkpoints.

The study was presented last week at the annual meeting of the Radiological Society of North America in Chicago.