" Mr. Alexander, you are radiant " said the customs officer " YouÕre not so bad yourself fella" Alexander said.

DERBY LINE, VT | ( Published in the Caledonian Record May 10th 2008 ) Nuclear medicine scans help doctors see how the heart or other vital organs work. The nuclear material used is such a low-grade, low-dose radioisotope that it loses its potency within a few hours and poses no harm to patients or to those around them.

But it can also raise an alarm at the US border, where inspectors are armed with scanners to pick up any radiation coming from people or their vehicles.

Nuclear medicine technologist Gary Kibbee has used nuclear isotopes to do tests at North Country Hospital in Newport for years. He has been amused to hear that some of his patients have intentionally gone across the border within days of having the scan, just to see if it trips the alarm at the border.

"A lot of people will do it to be funny," Kibbee said. Not everyone finds it funny, however.

Orleans County freelance photographer Gordon Alexander recently found out what happens when someone who underwent a cardiac nuclear medicine scan crosses the border before the radioisotope has completely decayed.

Alexander had the test on May 3. Two days later, he attempted to cross into the US through the Derby Line port of entry on Main Street. The initial inspector pulled him over for what turned out to be a half-hour inspection.

"After first checking my passport in his booth, the immigration officer asked if I had participated in any medical procedure lately," Alexander said. Alexander had expected all traces of the nuclear material would have left his body by then. But it had not, and inspectors used a more sophisticated scanner to check out Alexander and his vehicle, which showed no sign of radiation.

Alexander said he was a bit concerned because he didnÕt expect to have enough isotopes left in his body to trip the alarm. When he went into Canada, he was pronounced all clear of radiation by the Stanstead, Quebec, inspectors, Alexander said.

Alexander said he had received a very low dose of technetium-99m (Tc-99m) during what he called a two-part stress test to look at his heart.

According to the Washington State Department of Health online dictionary, Tc-99m has a six-hour half-life that is long enough to examine the organ that may be diseased, but is short enough to minimize the impact on the patient.

Nuclear imaging is the opposite of an X-ray. It shows an image of the heart in action, Kibbee said. It is also used to scan bones, the thyroid, kidneys and other organs. The radiation is mixed with a "tagging" agent that is specific to the organ being scanned, he said.

Because Tc-99m is only good for scans within six hours and decays completely within sixty hours, it has a very short shelf life in the medical field. It must be made to the specific dose needed by each patient and delivered for immediate use every day, Kibbee said. Some men do not completely release all their urine within the usual time and all radioactive residues wonÕt have left the body within forty-eight hours, Kibbee said.

"ItÕs amazing how sensitive their equipment is," Kibbee said.

Tc-99m is not considered a threat of any kind, he noted. The border officials are looking for radioactive material that has a much longer half-life, which may take years or millennia to lose radioactivity, he said. Inspectors wear portable detectors on their belts, said Ted Woo, public relations officer for US Customs and Border Protection.

The detector is very sensitive, Woo said. "IÕve personally been at meetings with someone who had treatment and my personal device went off." It could go off even if someone in a car who has had nuclear medicine scanning drives by, he added.

This type of detector has been common for years at border crossings. It is possible that some hospitals are not aware of how sensitive the detectors are, Woo said. The inspectorÕs personal detector picks up the initial alert that radiation is present, Woo said. Then the visitor may need to be scanned with another non-intrusive device.

That secondary inspection likely is able to identify the type of radiation in the personÕs body, which will give an all clear for the visitor, Kibbee said. Other types of radiation, like that in old watch dials, would set off detectors, he said.

Kibbee said he usually provides a letter to the patient receiving a nuclear medicine scan that identifies the type of isotope used, the date and location of the test, and several names and a phone number in case there are questions. He did not provide such a letter to Alexander, which Kibbee called an oversight on his part.

People who are regular border crossers need to raise that point at the hospital where they are to receive nuclear medicine treatment or imaging, he said.

Alexander later received a copy of the standard letter, which gives KibbeeÕs name and the phone number of the diagnostic imaging department at North Country Hospital.

It has not been the first time that a patient of KibbeeÕs has set of an alarm at the border, but he said he has never had a telephone call from a border inspector questioning the treatment or denying entrance to the US because of the scan. Hospital privacy rules restrict people like Kibbee from going into detail about patients and their treatment.

"I am very limited in what I can say" to inspectors, Kibbee said. However, Kibbee said he can identify the type of radiation scan that he uses and what he does not use.

Detection of the residue from nuclear medicine imaging is a common experience on the border, Woo said.

A half-hour delay at a land border might not be a problem for some people. It could be at airports, Kibbee said. "If someone is going on an airplane, I wish they would tell me," he said.