by Michael Ozner
The
Dangers of Radiation
by
Dr. Michael Ozner, author of The
Great American Heart Hoax:
Lifesaving
Advice Your Doctor Should Tell You About Heart Disease Prevention
(But Probably Never Will)
The most serious problem with the
widespread use of CAT scans is the radiation these devices leave in
our bodies. CAT scans are not simple chest X-rays, which deliver only
a small amount of radiation. Instead, they expose the patient to a
significant amount of radiation, and radiation in significant doses
has been shown to increase the risk of cancer.
We are all
exposed to "natural background radiation" -- that is,
radiation from the sun, radon gas, rocks in the ground, cosmic rays,
and other sources that usually can't be avoided in our daily lives.
Radiation is measured in units called "millisieverts"
(mSv), and we can use millisieverts to compare this natural radiation
to the levels of radiation we get from other sources, such as medical
tests. For instance, a chest X-ray provides about 0.02 mSv, or the
equivalent of 2.4 days of natural background radiation. A CAT scan of
the abdomen, on the other hand, provides about 10.0 mSv, or the
equivalent of 500 chest X-rays or 3.3 years of natural
background radiation. And a 64-slice wholebody CAT scan provides 15.2
mSv for men and 21.4 mSv for women (women's denser body tissue and
breasts require higher doses to get clear images) -- quite a
difference, especially when you realize that the radiation you
receive is cumulative.
Now compare these numbers with the
level of radiation to which Japanese survivors of the atomic bomb
explosions at Hiroshima and Nagasaki were exposed: an average dose of
between 5 and 20 mSv, with some doses as high as 50 mSv. A single CAT
scan can easily exceed that average. And since radiation from all
sources remains in our bodies for life, the likelihood of the average
twenty-first-century patient matching or exceeding that average, even
without a CAT scan, is very high. In the New York Times, Roni
Caryn Rabin reported that recent studies indicate that the amount of
radiation in the bodies of Americans increased 600 percent between
1980 and 2006, with the bulk of this increase attributed to
diagnostic imaging procedures. In 1980 about 3 million of these
procedures were performed, but by 2006 the number had skyrocketed to
62 million. If you were to follow some popular recommendations to
have an annual CAT scan, plus one virtual colonoscopy and a coronary
angiogram (both of which also deliver large doses of radiation), in
the space of only a few years you could easily be exposed to more
radiation than even the most highly exposed Hiroshima survivor.
The
World Health Organization, Centers for Disease Control and
Prevention, and the National Institute of Environmental Health
Sciences have all classified X-rays as carcinogens based on the fact
that they have been linked to leukemia and cancers of the breast,
lungs, and thyroid. The risk of a fatal cancer from a chest X-ray has
been estimated as one in a million or more- in other words, very
remote. But the risk of a fatal cancer in a person who has had just
one of these new 64-slice CAT scans is estimated to be one in 2,000.
In one study reported in the Journal of the American Medical
Association, the risk of cancer in people having 64-slice CAT
scans of the heart was found to be greater for young women than young
men. Researchers found that one of every 143 women scanned at age
twenty will develop cancer, usually breast cancer; the risk for
forty-year-old women falls to one in 284. For men, the cancer risk
was one in 686 for a twenty-year-old, and one in 1,007 for a
forty-year-old. The reason for the gender difference in risk lies in
the fact that breast tissue is very sensitive to radiation and the
heart can't be scanned without radiation exposure to breast tissue.
Clearly, administering CAT scans simply for screening is a risk we
shouldn't be recommending people take.
There is no level of
radiation exposure below which you can assume you're safe. Of course,
everyone is different and no one will be affected by radiation in the
same way. And when we talk about the radiation doses for various
medical procedures, we are always talking about estimates rather than
exact figures. Depending on where you have your CAT scan done, who is
performing it, what machine is being used, and what condition is
being screened for, the doses can vary. But radiation interferes with
the body's natural immune system the same way regardless of dose.
Your body keeps you healthy by attacking free radicals, scavengers,
and cancer cells inside you, but its resources are finite. A sudden
blast of radiation can be just the impetus needed to allow leukemia,
breast cancer, or some other cancer to begin developing.
Cost
When CAT scan machines were first widely introduced in
the early 1980s, they were heavily publicized and marketed. Because
the scans were normally not covered by insurance, the cost was all
out-of-pocket for the patient. So a lot of people, especially those
who had cause to be worried about potential health risks due to
family history, put thousands of dollars on the table -- even if they
couldn't afford it -- all because they and their families believed
the tests would "save their lives" by revealing hidden
life-threatening conditions. Some of my own patients told me that
imaging centers had charged them up to $2,500 for a single scan;
other patients have reported paying anywhere from $500 to $5,000. And
many of these centers were not run by doctors but by business people
who were very aggressive in their marketing.
Hospitals,
doctors, and scanning centers had invested several million dollars in
each one of these scanners, and naturally they wanted to recoup their
costs. So there was a lot of pressure put on patients to have CAT
scans when they may not have needed them and a lot of marketing done
to doctors about how they could double their income by using these
machines in their practices. The dangers were being completely
ignored. Unfortunately, this is still largely the case.
Effectiveness
Here's what most people do not
realize: there is absolutely no data to prove that CAT scans are
medically useful for people who do not have any symptoms. According
to the FDA website:
The FDA has never approved
CT for screening any part of the body for any specific disease, let
alone for screening the whole body when there are no specific
symptoms of disease at all. No manufacturer has submitted data to FDA
to support the safety and efficacy of screening claims for whole-body
CT screening.
They further state:
the
FDA knows of no data demonstrating that whole-body CT screening is
effective in detecting any particular disease early enough for the
disease to be managed, treated, or cured and advantageously spare a
person at least some of the detriment associated with serious illness
or premature death.
In addition, the American College
of Radiology, the American College of Cardiology/American Heart
Association, the American Association of Physicists in Medicine, and
the American Medical Association, among others, do not recommend CAT
scans. Medicare and most insurance companies do not cover CAT scans
for screening because the tests have never been shown to provide
information in addition to what we can already learn through doing a
medical history, a physical exam, and blood tests.
This excerpt is a
digitally scanned reproduction of text from print. Although it has
been proofread, occasional errors may appear due to the scanning
process. Please refer to the finished book for accuracy.
Copyright © 2008 Michael
Ozner, MD, FACC, FAHA