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Health October 2012

Aid for Age

Hold the Radiation, Please

By Tait Trussell

The catch is that some of these valuable tests also expose you to ionizing radiation. And, unfortunately, that can quite possibly damage cells in your body and risk what could be worse than a heart condition — namely cancer.

We may be getting far too much radiation. Harvard Medical School doctors think so.

A variety of tests available to medicine these days provides invaluable means for diagnosing and treating serious diseases and conditions. But, with all the tests comes a danger of excessive radiation.

If you have a heart condition, your doctor or a cardiologist you may be referred to, could consider such tests as an electrocardiogram (ECG), cardiac catheterization, echocardiogram (ultrasound), radionuclide stress test, coronary CT angiogram, radionuclide myocardial perfusion imaging, or cardio magnetic resonance imaging (MRI).

That seems like an overload of technical-sounding tests. But these are tests that give the heart specialists evidence they need to address any problems with that most vital organ in your body — the heart.

The catch is that some of these valuable tests also expose you to ionizing radiation. And, unfortunately, that can quite possibly damage cells in your body and risk what could be worse than a heart condition — namely cancer.

Scientists have yet to confirm a direct link between cardiac imaging tests and cancer. But doctors are now limiting the amount of radiation delivered by these tests. Dr. Warren Manning, chief of noninvasive cardiac imaging and testing at Beth Israel Deaconess Medical Center and a professor at Harvard Medical School, reported, “Until 10 years ago, we didn’t realize how much radiation exposure was incurred by certain tests. Now we know. Moreover it’s not only the dose that raises risk, it’s also where and when the radiation is given.”

Dr. Manning adds: “One or two CT scans over a lifetime is appropriate [In other words not dangerous] “But,” he continues, “if you have a condition that requires continuous monitoring, a test that does not expose you to ionizing radiation, like cardiac ultrasound, or MRI, may be preferable.”

In our normal ways of spending our days — out in the sunshine, or traveling on trips by plane, we are exposed to small doses of radiation. But this exposure apparently is not dangerous, in and of itself. Otherwise, airline pilots would have a higher incidence of cancer. “But they don’t,” says Dr. Manning.

The American College of Radiology has set lifetime radiation limits at a conservative 100 millisieverts (mSv). One mSv is about the amount of radiation you get in a year on average. Below that level, there is probably no risk, Dr. Manning figures.

CT scans send out very high dose of radiation. A CT scan stands for Computed Tomography scan. It is also known as a CAT (Computer Axial Tomography) scan. It’s a medical imaging method that employs tomography. Tomography is the process of generating a two-dimensional image of a slice or section through a 3-dimensional object (a tomogram). The medical device (the machine) is called a CTG scanner that uses X-rays. It used to be called an EMI scan.

Doctors have become concerned about CT scans because they have been used so much. When the amount of radiation from a CT scan is added to the amount you get from dental x-rays, chest x-rays, mammograms, and other tests on you in the past, it’s easy to surpass the exposure limit, Dr. Manning cautions. If you are in your 80s, he says, you probably will outlive the danger. Those of us in our 80s hope we have outlived a lot of things.

The American College of Radiology now stresses the importance of using tests with as little radiology as possible. New approaches, for example, allow cardiac CT scans to be used with one-sixth of the conventional radiation dose. The American College of Cardiology Foundation is collaborating with the imaging societies to cut down on the number of exposures people get by recommending how often specific tests should be done, as well as encouraging doctors to use radiation-free tests, such as ECG (electrocardiology), and MRI whenever possible. These tests pose no radiation risk.

 

Tait Trussell is an old guy and fourth-generation professional journalist who writes extensively about aging issues among a myriad of diverse topics.

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