Patients having radiation treatments should be warned they may falsely trigger security alarms, say experts.
Some patients might trigger alarms up to 12 weeks after treatment
Their advice follows the case of a patient who set off a US airport security alarm at check-in six weeks after receiving radioiodine therapy.
He was interrogated, strip-searched and finally released, after a long delay and much embarrassment, the British Medical Journal reports.
Each year 10,000 UK people are treated with radioiodine for thyroid problems.
And increasing numbers of diagnostic and therapeutic procedures, including some lung, heart and bone scans, use radioactive particles.
Given the current political climate, airport authorities are keen to detect any radioactive material being carried by passengers, and have installed sensitive alarms.
Researchers at City Hospital, Birmingham, say that having heard about the problems their 46-year-old patient encountered, they began issuing all patients with a radionuclide card explaining the risk of persisting radioactivity following such treatment and problems this might cause, including the risk of radiation alarms being triggered.
When they searched medical literature they found four similar cases.
In the first report, dated 1986, two patients were detained and later released after trying to enter the White House for a public tour four days after exercise testing with a thallium scan.
In 1988, a patient triggered a bank's security alarm, again because of an earlier thallium scan.
In 2004, a 55-year-old pilot was detained after setting off airport radiation detector alarms while travelling as a crew member to Moscow.
He was released later the same day when it transpired the radioactivity detected was the result of a heart scan he had undergone two days earlier. Experts estimate that some patients might trigger alarms up to 12 weeks after radioactive diagnostic and therapeutic procedures.
Writing in the BMJ, Dr Kalyan Kumar Gangopadhyay and colleagues said: "Airports worldwide are deploying more sensitive radiation detection systems and one would therefore expect more such cases unless we take the responsibility of forewarning our patients."
Dundee University experts Dr Daniel Cuthbertson and Dr John Davidson said new guidelines due on the use of radioiodine for thyroid disease should include this advice.
Patients who have received treatment involving radioactive particles are already advised to avoid public transport for two weeks so that they do not expose nearby passengers to radioactivity.
Patients with young children at home are also advised to avoid prolonged daily close contact - within less than 1 metre - with them for a time dependent on the dose of radioiodine administered.
A spokeswoman from the Royal College of Physicians, the organisation that is due to publish new guidance on radioiodine use for thyroid disease, said: "The guidelines are due for publication in November, so there will be time for this new issue to be considered."