Radiation Treatment Fools New Hampshire Trooper’s Sensor

By | December 6, 2008

David Abel from the Boston Globe has this very interesting story up:

The disabled 60-year-old driving a royal blue Chevy Malibu on New Hampshire’s Spaulding Turnpike didn’t look like an emissary of Al Qaeda.

But there was something menacing coming from his car.

On his way home last month after receiving a PET scan at Portsmouth Regional Hospital, Michael Rosenthal noticed a State Police sport utility vehicle driving next to him and the trooper inside staring at him strangely. The trooper then sped in front of Rosenthal, slowed down, and pulled behind him.

“I was in the granny lane, driving on cruise control, taking my time, when all of a sudden I looked over and I saw this trooper with a puzzled look,” said Rosenthal, a former New York City police officer who lives in East Wakefield, N.H. “When he put on his blue lights and pulled me over, I knew it wasn’t a normal traffic stop.”

The trooper, Bill Burke, walked over to Rosenthal, but the State Police veteran didn’t ask for his license or registration. Instead, he had an all-too-knowing, Big Brotherlike question.

“Were you in contact with any radioactivity today?” he asked.

Rosenthal began to wonder whether his veins were glowing from the chemicals injected for the scan.

“I thought it was an odd question, like I was on `Candid Camera,”‘ Rosenthal said.

He asked Burke why he was asking the question, and the trooper explained that he carries a radioactivity sensor and that something in Rosenthal’s car set off the alarm.

“It’s very rare that you get them going off for a vehicle going by,” said Sergeant John Begin of State Police Troop G, which monitors radioactive waste in commercial vehicles passing through New Hampshire. “I can only think of three or four cases.”

Rosenthal registered a six on the sensor’s scale, which goes from one to nine, with nine the highest amount of radioactivity.

Begin said that about 30 New Hampshire troopers carry the sensors, which are the size of a bulky cellphone and can detect radioactivity as far away as 100 feet. New Hampshire bought the radiation-detecting equipment, called Mini rad-Ds and made by D-tect Systems, with a grant from the US Department of Homeland Security before the 2004 Democratic National Convention in Boston as part of efforts to prevent attacks on the city.

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On the side of the turnpike that Nov. 21, Rosenthal explained to Burke that he had just come from having a positron emission tomography scan, which requires an injection of short-lived radioactive isotopes to identify any unhealthy cellular activity. The isotopes can remain in the body for as long as 18 hours, and patients are advised to keep their distance from others for that period.

“I told him I was surprised his equipment could detect the radioactivity in my body,” Rosenthal said.

But Burke didn’t take Rosenthal’s word for it. He asked him to prove it.

“I was very lucky that I had the documents with me from the hospital,” he said. “After that, he was satisfied and sent me on my way.”

Like hospitals around the country, Portsmouth Regional does hundreds of scans a week. Nancy Notis, a hospital spokeswoman, said Rosenthal’s case is the first time they’ve heard of a patient being pulled over for emitting radioactivity.

As a result, she said, the hospital is reviewing whether to alert patients that they could be stopped by police.

Despite his delay getting home, Rosenthal said he is happy to know the police are on the prowl for terrorists.

“It made me feel good in one respect – that our money is going to good purposes,” he said.- officer.com

Here is more information about how PET scans work:

The most commonly used tracer is called FDG (fluorodeoxyglucose), so the test is sometimes called an FDG-PET scan. Before the PET scan, a small amount of FDG is injected into the patient. Because cancer grows at a faster rate than healthy tissue, cancer cells absorb more of the FDG. The PET scanner detects the radiation given off by the FDG and produces color-coded images of the body that show both normal and cancerous tissue. – acrin

A positron-emitting radionuclide is introduced, usually by injection, and accumulates in the target tissue. As it decays it emits a positron, which promptly combines with a nearby electron resulting in the simultaneous emission of two identifiable gamma rays in opposite directions. These are detected by a PET camera and give very precise indication of their origin. PET’s most important clinical role is in oncology, with fluorine-18 as the tracer, since it has proven to be the most accurate non-invasive method of detecting and evaluating most cancers. It is also well used in cardiac and brain imaging.€  – worldnuclear

How radioactive is the fluorine-18 /€  FDG / fluorodeoxyglucose?

It has a physical half life of 110 minutes, exits the body in the urine (If you have a PET scan, drink lots of water to flush the radioactivity out. ), and has a photon energy of 511 keV according to radswiki. FDG emits gamma radiation. According to one site, a person standing three feet from the patient an hour after the PET scan will get about 0.004 rad/hour and after 8 hours, that would drop to about 0.0005 rad/hour. One site says the dose is about 7 mSv, or 0.7 rem/rad.

Normal PET Scan

Gamma rays (gamma photons), discovered during Uranium experiments by French Chemist and Physicist Pual Ulrich Villard in 1900, travel at the speed of light are the most penetrating radiation from natural and man-made sources.

… gamma rays can cause serious damage when absorbed by living tissue, and they are therefore a health hazard. … as a form of ionizing radiation they have the ability to effect molecular changes, giving them the potential to cause cancer when DNA is affected. … the average total amount of radiation received in one year per inhabitant in the USA is .36 cSv.[3]

… among nuclear workers, who receive an average yearly radiation dose of 1.9 cSv€  … the risk of dying from cancer (excluding leukemia) increases by 2 percent. For a dose of 10 cSv, that risk increase is at 10 percent. – wiki

How does cSv relate to rads, rems, and other units of raditation?

There are many different units in which radiation doses are expressed and this can be confusing. For example, several years ago I had an Upper GI investigation where I got approximately 2.440€  mSV radiation dose.€  I know that you start to see physical effects when you get to about 5-10 rems. How many Upper GIs would that be?€  1 rem is 10 mSv so, I’d be in trouble if I had more than 20 of them in a short time.

How safe is a PET scan to the patient?

PET scanning is invasive, in that radioactive material is injected into the subject. However the total dose of radiation is small, usually around 7 mSv. This can be compared to 2.2 mSv average annual background radiation in the UK, 0.02 mSv for a chest X-Ray, up to 8 mSv for a CT scan of the chest, 2-6 mSv per annum for aircrew, and 7.8 mSv per annum background exposure in Cornwall (Data from UK National Radiological Protection Board). – nm

In other words any more than 5 PET scans in a short time could give you mild radiation sickness.€  Of course, this is an average. It is possible that even a very small dose of high energy gamma rays could cause a mutation that might lead to cancer.

Luckily, our bodies repair their own DNA quite well… usually. Certain genes in our bodies are repsonsible for DNA repair. Their effectiveness declines with age, because the DNA of the repair genes can also be damaged over time.

Your body is equipped to handle damage that occurs to DNA although within reason. … Fortunately, there are nearly a hundred and fifty genes that have been identified as playing a key role in DNA repair. … it is expected that many more DNA repair genes will be identified in the coming years. Their identification can hopefully provide clues to keep DNA from deteriorating and malfunctioning, which will have important ramifications for disease.exploredna

Can gamma radiation be blocked?

The goal with protection from radiation is to decrease the time you are exposed, increase the distance from the source, and increase the shielding.

Gamma rays can travel hundreds to thousands of meters in air before spending their energy. They can pass through many kinds of materials, including human tissue.

… a practical shield in a fallout shelter is ten halving-thicknesses of packed dirt, which is 90 cm (3 ft) of dirt. This reduces gamma rays by a factor of 1/1,024, which is 1/2 multiplied by itself ten times. –wiki

Each 1 cm (0.4 inches) of lead , 6 cm (2.4 inches) of concrete, or 150 m (500 ft) of air will reduce gamma ray intensity by 50%.

Based on all of this, it makes sense that the officer’s Mini rad detector picked€  up a PET scan patient in a passing car.

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