A recent study in the New England Journal of Medicine raises concern that Americans are being exposed to potentially harmful amounts of ionizing radiation from medical imaging, especially CAT Scans and myocardial perfusion imaging. The latter is a study of heart function done in conjunction with cardiac stress testing.

The first sentence of the article in the August 27, 2009 issue reads as follows:

“Experimental and epidemiological evidence has linked exposure to low-dose ionizing radiation with the development of solid cancers and leukemia.”


Workers in the health care and nuclear industries are monitored and restricted to radiation doses of 20mSv a year. The study shows that an estimated 4 million American under the age of 65 are exposed on an annual basis to more than that.

Radiation exposure of patients subjected to medical imaging is not monitored and restricted. More than 30% of men and 40% of women exposed to this amount were under 50 years of age.

There is an inherent problem in balancing immediate medical need with the fact that it can take years before radiation exposure may show up as cancer. This conflict requires that health care providers inform patients of the dangers of radiation form medical imaging. In one study cited in this same article, less than 50% of radiologists and only 9% of emergency room physicians are even aware that CAT Scans are associated with an increased cancer risk.


The study authors note that cancer is more likely to develop in women than in men after similar levels of exposure. They also observe that most radiation exposures occur in outpatient settings.

Although not stated in this study, there in fact no good prospective randomized controlled studies that show clear benefit from all these CAT scans and myocardial perfusion imagings, given their potential cancer risk. Studies have linked low dose ionizing radiation from medical imaging with up to 2% of solid cancers and leukemia.

In fact, Americans today are exposed to over seven times as much radiation from diagnostic scans compared to 1980, with no clear benefit from well designed studies. Medicare spending on imaging doubled to $14 billion a year between the years 200 and 2006. (March 3, 2009 report from the National Council on Radiation Protection and Measurements)


According to Dr. James Thrall, chair of the American College of Radiology’s Board of Chancellors “. . . one of the things we have seen in the imaging world is that many physicians look at imaging as the solution to their financial problems,” Thrall is head of radiology at Massachusetts General Hospital in Boston.

He stated imaging technology has created financial incentives for some doctors to cash in. They simply refer patients to get imaging tests on equipment in their own practices. (Phone interview reported in Reuters, March 4, 2009 – see familiesagainstcancer.org)

From 1998 to 2005, the number of self-referred, in-office medical scans done on Medicare patients grew at triple the rate of the same exams performed in all other settings, such as hospitals or stand-alone imaging centers.

Part of the problem is that some unscrupulous doctors are exploiting high reimbursement levels for medical imaging by purchasing their own equipment then self-referring at excessively high rates.

The bigger issue at hand may simply be that doctors order too many scans, period.

There are many reasons for this, including the pressure to supply concerned patients with supposedly definitive techno-answers to worrisome medical problems. Many doctors are afraid of missing cancer in patients and order all these studies because they don’t want to end up being sued.

It appears that the failure to properly regulate these practices is harming many more people than it helps.


Whenever a doctor orders a CAT Scan or cardiac stress test with myocardial perfusion imaging, ask whether the risk of harm from radiation outweighs the potential benefits. At least this will allow you and your doctor to engage in joint informed decision-making.

Alan Inglis MD
American Country Doctor


  • Dear Dr. Inglis,

    I am wondering if you can explain what is the “myocardial perfusion imaging”? Is it related to MRI?

    I have had several echocardiograms done by Mayo Clinic. The way it works, as described to me by the technician who performed these tests, is through ultrasonic imaging. Therefore, it did not involve “ionizing radiation” (caused by X-ray?), Or, did it?



  • The question I always ask is what good the finding, whatever it may be, is? What can you do about it? I asked a prominent cardiologist what the options were, were we to find blockage, for instance. He said, “well, we could put in a stent, do and angioplasty, or even a bypass. And I said, doctor, I feel great. I’m 63 years old, I jog up 3 tall flights of stairs without even panting, but more to the point, I am a biologist and I believe in green non-burial. There is no such thing as green burial; burial is the highest form of natural blasphemy. (In nature you lie where you die. Nature is designed to redistribute the nutrients, and so long as the earth lives, you live as a result). “So, Doc, excuse me, but your kind of priest has no dominion over me. Like Thoreau, I am looking to see over the next hill, and right now I ain’t broke and have nothing to fix. You’d be amazed at how natural communion removes fear from the liturgies of medical testing.

  • I believe you may have left out a reason for excessive scans: protection against lawsuits. If a doctor misses something because he didn’t do a scan, he would be more vulnerable to a lawsuit later. This is also a contributing factor to the high cost of care.

  • Hello,

    Agreed. I mentioned that doctors are terrified of missing a cancer, I believe, and indeed one of the reasons is the fear of law suit.
    Thanks for your interest.

    Regards, Alan Inglis MD

  • Hi,

    Emerging case literature suggests the possibibility of plaque reversal with aggressive “full court press” statins, niacin AND omega 3s, anti-inflammatory diet and moderate exercise and stress reduction, possibly dropping drigs after a year or two. Plaque can be safely appreciated, it appears, with a Carotid Intima Media Thickness ultrasound. Newer, emerging but with a lot of promising data.

    Thanks, Alan Inglis MD

  • Hi,

    The immaging I refer would not be the echocardiograms, which are a kind of ultrasound. The perfusion scans would be the common “nuclear stress tests”.

    Thanks for your patience. Finally getting fully up to speed with my web sites mechanics!

    Regards, Alan Inglis MD

Leave a Reply

Your email address will not be published. Required fields are marked *