[ RadSafe ] Traveling After Nuclear Medicine Procedure May Not Fly

donald_flahardy at fpl.com donald_flahardy at fpl.com
Wed Jul 27 15:34:38 CDT 2005

The length of time for which the patient would set off radiation monitors
needs to be understood by those in the medical profession.  I have dealt
with employees whose doctor told them not to worry, that the Thallium would
be long gone by the time they returned to work.  Their doctor was correct
with respect to the medical significance of what would remain after a few
days but did not appreciate the contribution of Thallium 202 contained in
the Thallium 201 administration (12 day half-life vs 3 days for Tl 201),
nor did the doctor have an appreciation for the sensitivity of radiation
detectors at our facility.  I typically see the need for 3 - 4 weeks before
a patient can pass through our portal monitors without causing an alarm.  I
know little about the instrumentation used for Homeland security other than
that these instruments vary greatly in sensitivity.  If I become such a
patient I will assume the most sensitive devices are in use in order to
avoid a hassle.

Donald Flahardy, CHP
Sr. Health Physicist
FPL Energy Seabrook LLC
Seabrook, NH
(603) 773-7312 office
(603) 944-0000 cell
(603 771-2432 pager
donald_flahardy at fpl.com

                      "Susan Gawarecki"                                                                                                
                      <loc at icx.net>            To:       "RADSAFE" <radsafe at radlab.nl>                                                 
                      Sent by:                 cc:                                                                                     
                      radsafe-bounces at r        Subject:  [ RadSafe ] Traveling After Nuclear Medicine Procedure May Not Fly            
                      07/22/2005 01:25                                                                                                 

Traveling After Nuclear Medicine Procedure May Not Fly

By Michael Smith , MedPage Today Staff Writer
Reviewed by Zalman S. Agus, MD; Emeritus Professor at the University of
Pennsylvania School of Medicine.

LONDON, July 21-The threat of terrorism has made it tougher for patients
who have undergone radioisotope procedures to slip quietly past
radiation detectors deployed in airports and many other public places.

A 55-year-old commercial pilot learned that the hard way, when he was
detained for questioning at Moscow's airport two days after having a
thallium-201 myocardial perfusion scintigram.

After "extensive interrogation," the pilot was released, only to trip
radiation detectors again four days later while leaving Moscow,
according to a case report in the July 23 issue of The Lancet.

The case and others like it suggest "it is important to warn patients
having had a thallium scan that they may trigger radiation detectors for
up to 30 days," wrote Richard Underwood, M.D., and colleagues of
London's Royal Brompton Hospital.

In fact, the authors suggested, it should be standard practice to give
patients an information card after they've had diagnostic or therapeutic
procedures involving radioisotopes.

The card would give:

    * The date and place of the procedure.
    * The radioisotope used and its half-life.
    * The potential duration of radioactive emissions.
    * Who to call for verification.

More than 18 million such procedures are carried out every year and more
and more radiation detectors are in place in what the U.S. Nuclear
Regulatory Commission calls "critical infrastructure," including
airports, banks, railway stations, and highway tunnels.

In 2003, the commission urged that nuclear medicine specialists make a
point of emphasizing that patients should follow the written
instructions they get after a procedure, which usually suggest not using
public transport within two days.

The recommendation came after a New York State police pulled over a bus
traveling from New York to Atlantic City after it tripped a radiation
detector in a highway tunnel leading out of the city.

It turned out that one of the passengers had received a dose of
iodine-131 earlier the same day, but had ignored her doctor's written
suggestion to avoid public transit for at least two days.

To "avoid unnecessary concern by law enforcement authorities," the
commission suggested nuclear medicine specialists should "consider"
giving patients their business card and written information about the

A spokesman for the commission said there's no legal requirement to
report such events, so the commission doesn't know how common they are.

But reports date back to at least 1986, when a letter to the New England
Journal of Medicine noted two incidents in which Secret Service agents
seized patients who set off radiation detectors at the White House after
thallium stress tests.

The half-life of thallium-201 is 73 hours; the usual intravenous dose is
80 mega Becquerel. That means, wrote Dr. Underwood, that patients may
trigger radiation detectors for at least two weeks.

In fact, highly sensitive modern detectors -- like those issued to
police and other security personnel -- may detect the traces of
thallium-210 for as much as a month, according to a report at the 2004
meeting of the Radiological Society of North America.

The least durable radioisotope was fluorine-18, which lasted about a
day; the most durable was iodine-131, which in some cases could still
trigger detectors 95 days after it was administered.

The pilot -- who had never complained of chest pain or shortness of
breath -- was shown to have a dilated and hypertrophied left ventricle
with no evidence of inducible ischemia, the authors noted.

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