By AL BAKER
In one case last spring, a man being treated for an overactive thyroid gland was stopped by the authorities on two occasions while at a subway stop at Pennsylvania Station. In another case about a month ago, a woman who had undergone a diagnostic heart study was stopped while trying to drive out of Manhattan through a tunnel.
In both cases, the people involved had been treated with radioactive materials. And in both cases, doctors said, they were stopped by law enforcement officers armed with radiation detectors used to track possible terrorists.
Such reports are flowing into doctors' offices, physicians in the metropolitan region and elsewhere say.
The expanded use of radiation and metal detectors to guard against potential terrorism after Sept. 11, 2001, has prompted many unintended security stops, whether of cancer patients undergoing radiation treatment or of travelers with prosthetic limbs or pacemakers passing through airport metal detectors. Drug dealers have been known to mark their goods with radioactive material as a way of tracing it, and one doctor said he had heard of shipments being stopped at border crossings in Europe.
''This is all along the law of unintended consequences,'' Fred Mettler, the chairman of radiology and nuclear medicine at the University of New Mexico, said yesterday. ''The question is, 'How does the poor patient convince the law enforcement authorities that they are truly patients and not terrorists?' ''
To better prepare their patients for security episodes relating to their radioactive treatment, and to keep them from being mistaken for those who would do harm, doctors in New York are drawing up guidelines telling patients how they should react. Doctors say Police Department officials have recommended that patients carry letters from their doctors to avoid confusion, but the police said that they had issued no broad recommendations and that such letters would not suffice to resolve the matter.
Countless patients being treated for a variety of ailments may have had radioactive isotopes injected into their bodies and can therefore set off alarms at borders, bridge crossings or transportation hubs, or trigger the attention of authorities who have portable radiation detectors.
The woman stopped recently near the tunnel contacted her physician, Dr. Chaitanya Divgi, an expert in nuclear medicine in the radiology department at Memorial Sloan-Kettering Cancer Center. ''She called me from the cellphone,'' said Dr. Divgi, who could not identify the tunnel but added that he spoke with the officer and that the woman was later able to pass through. ''Doctors are talking about patients being stopped, about security alarms going off after patients are being administered radio pharmaceuticals.''
Doctors say they have not criticized law enforcement officers for their efforts, under which patients may be questioned intensely and subjected to body searches. Rather, most interviewed yesterday said the recent incidents pointed out one of the sometimes odd byproducts of the nation's heightened state of alert and gave them confidence that the authorities' detection equipment was working.
Dr. Christoph Buettner, an endocrinologist treating the man with the overactive thyroid who was stopped at Penn Station, said: ''They did not treat him badly. They just detected radioactivity and they had to pursue that, and that is obviously the right thing to do in these circumstances, in these times. We just want the cops to have a way to identify patients who have been treated with radioactive isotopes.''
As part of the Police Department's new measures to guard against potential terrorism, radiation detectors have been installed outside several city buildings. Also, about 250 radiation detectors, worn on the belt, have been distributed to officers. The devices are intended to form a sort of moving detection curtain so that police officers can interact with the public as they look for radioactive material.
When the Police Department installed radiation detection devices outside Police Headquarters in Lower Manhattan in June, a police inspector who had been injected with radioactive dye for a stress test reportedly set them off
The man with the overactive thyroid gland was stopped after authorities somehow detected gamma rays emitting from him and detained him for questioning, said Dr. Martin I. Surks, the director of endocrinology at Montefiore Medical Center who oversaw the man's treatment, which was administered by Dr. Buettner. The doctors could not say which law enforcement agency was involved.
A Police Department official said last night that the department could find no records to confirm that incident. Tom Kelly, a spokesman for the Metropolitan Transportation Authority, said he had no record of it, either. Cliff Black, an Amtrak spokesman, said yesterday that he was still researching the matter.
According to his doctors, the patient, a 34-year-old fitness instructor from the Bronx, was being treated for Graves' disease, a thyroid condition, with radioactive iodine (iodine-131). Sixty-three percent of it was concentrated into his thyroid gland, in the front of his windpipe in his lower neck, the doctors said.
''Three weeks after treatment, he returned to our clinic complaining that he had been strip-searched twice at major Manhattan subway stations,'' Dr. Surks and Dr. Buettner wrote in a letter to be published today in The Journal of the American Medical Association. ''Police had identified him as emitting radiation and had detained him for further questioning.''
The doctors said that the patient had requested that he not be identified publicly and that they were unable to reach him by phone yesterday. In their letter to the the journal and in interviews yesterday, Dr. Surks and Dr. Buettner said a police official had recommended that physicians who treat patients with radioactive material give them letters describing the isotope and dose, its biological half-life and the date and time of treatment. The doctors also said the police had recommended that patients be given a telephone number where they can reach the physician 24 hours a day.
But a police official said last night that the department had made no such broad recommendation. The official said police officers would not treat a letter from a doctor as sole proof that someone was above suspicion, but would conduct an investigation first