Medical scans can trigger airport alarms for up to 30 days after

According to a new study, patients who have had medical scans should be warned that they could set off security alarms at airports for as long as a month afterwards.

The authors of the study are calling for information cards to be issued to people who have had scans involving radioisotopes, to decrease disruption as a result of the accidental alerts.

Apparently more than 18 million such diagnostic and therapeutic procedures are carried out each year.

Patients who have had radioisotopes in scans, involving the thyroid gland, bone, and blood flow to the heart muscle, as well as radioactive iodine therapy, are temporarily rendered radioactive, making them at risk of setting off radiation alarms.

A team of researchers at the Royal Brompton Hospital in London, have highlighted the case of a 55-year-old commercial pilot who had had a heart scan using a radioisotope of the element thallium.

He travelled to Moscow two days later as a crew member, but triggered radiation detector alarms going through customs and was subjected to extensive interrogation.

He was eventually released, but four days later the same thing happened again as he returned through the same airport.

Security officials eventually issued him with a special card to carry, which explained his risk of setting off alarms.

Professor Richard Underwood says as stricter measures, and more sensitive radiation detection systems, are being deployed at airports worldwide, it is important to warn patients having had a thallium scan that they may trigger radiation detectors for up to 30 days.

Underwood feels that it should be standard practice to issue patients with an information card after diagnostic or therapeutic procedures involving radioisotopes.

The card should state the date and place of the procedure, the radioisotope used and its half-life, potential duration of radioactive emissions from the patient, and details on who to contact for verification if necessary.

This he says, would lessen the impact of such false alarms and avoid unnecessary interrogations by airport security personnel.

The study is published in the Lancet.