Download CT Scans: What are the Real Risks?

by
O
ver the past 25 years,
Computed Tomography scans (CT scans) have
become one of the most powerful diagnostic imaging tests in health
care. The expanding indications for and
utilization of CT scans has significantly
improved our ability to diagnose and treat
a myriad of diseases efficiently and effectively. Their increased use, however, has
also significantly increased the exposure of
patients to higher levels of ionizing radiation. While this trend has been a concern to
radiologists and other physicians for many
years, several recent news articles have also
highlighted the potential health risks from
radiation exposure associated with CT.
Understanding of the risks that CT exams
may pose will help patients make informed
decisions about their own health.
Two recent studies published in the
Archives of Internal Medicine have brought
the issue of CT radiation dose into mainstream media coverage. One of these studies
analyzed doses of the CT exams performed
in the United States in 2007 and projected
that meaningful number of new cancers
could be induced by these exams alone. A
second study documents the wide variation
in radiation doses for common CT exams.
Media reports also highlight occasional
instances of patients receiving significant
radiation overexposures, which occurred
due to operator or equipment errors.
These studies highlight an issue that
concerns both health professionals and
patients. By some estimates, 72 million CT
scans were performed in the US in 2007.
A significant number of those scans were
performed on patients who have had a CT
scan previously in their lifetime. Radiation
dose received in the body is cumulative.
However, when CT exams are performed
only for appropriate reasons and using the
lowest doses possible, the risks posed to
each person can be kept quite low.
One of the difficult aspects of studying
the increased risk of cancer caused by CT
exams is the high baseline rate of malignancy
present in the US population. It has been
estimated that 42 out of every 100 individuals in this country will be diagnosed with
some type of malignancy in their lifetime.
Therefore, a large number of patients will
develop cancer whether or not they have
Thomas L. Presson, M.D.
a CT scan. The dose received from CT
scans effects patients by the same mechanisms as the dose they receive by living on
earth (cosmic radiation, radon exposure, air
travel). Thus assigning risk to each source
individually is imprecise at best.
Using a broad variety of sources,
including long-term studies of exposures
resulting from atomic-bomb survivors,
health professionals have begun to draw
conclusions about risks from one or several CT exams. Statistically, an individual’s increased risk of cancer from one CT,
or even several CT exams, remains quite
low, on the order of less than one percent.
The increased risk is real, however, and is
believed to likely increase with each additional exam. And, while overuse and overexposure are always concerns, this data
must be weighed against what may happen
to a patient if they do not have a CT scan.
Cancers induced by radiation would likely
take decades to develop, versus diseases
that may harm patients much sooner.
The challenge for health care providers, therefore, is to use CT most appropriately while minimizing the risk imposed to
patients. This challenge may be addressed
by providers and others at multiple points
in the care of individual patients as well as
populations at large.
First, physicians/providers should
order diagnostic exams using evidence
based/outcome criteria appropriate for
each patient. These diagnostic protocols
will guide physicians to the best test to
request for most patients. Many disease
entities may be imaged using a variety of
modalities so CT may not be necessary
or even best in many cases. If questions
or exceptions arise, consulting a radiologist will help make sure that only the most
appropriate exam is done.
Second, imaging providers should
employ stringent dose reduction guidelines for all CT exams. Exam protocols
should be established and maintained by
knowledgeable radiologists, who are best
able to tailor the exams to balance resolution required with the radiation dose delivered. The newest CT scanners employ
advanced dose reduction algorithms to
keep doses at a minimum. Breast and thyroid shielding may help minimize the dose
to these areas.
Third, in response to calls for national
standards in imaging, the American College of Radiology (ACR) has developed
certification criteria for imaging centers
and hospitals. These criteria assure that
each certified center meets high standards
for quality of imaging instruments, training of personnel, radiation dose and physician oversight. ACR certification for a
location can be quite challenging to meet;
however, several certified locations should
be available in your area.
Lastly, it is critical that children do not
receive adult radiation doses. All efforts
should be made to utilize alternative imaging methods; however, if a CT exam is necessary, only modified CT protocols should
be used to image pediatric patients.
Overall, based on current evidence, it is
reasonable to conclude that the radiation
dose patients receive from CT exams does
pose a small, but real, risk. For a single scan,
or even a small number of scans over a lifetime, this risk is likely no greater than from
normal environmental sources. However,
the risk will slightly increase with each
additional scan. Using methods described
above, and with care taken at every level,
the dose received can be minimized.
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Wake Radiology serves the Triangle area with 17 convenient locations and 55 board-certified radiologists
with imaging subspecialties available at each location.
For more information visit wakeradiology.com.
1214 Vaughn Road, Burlington, NC 27217
Dr. Presson, a vascular and interventional radiologist, is certified in diagnostic radiology by the
American Board of Radiology. In addition to serving
as director of Radiation Safety Programs for Wake
Radiology, Dr. Presson serves as radiation safety
officer at WakeMed Raleigh and WakeMed Cary
Hospitals. His clinical areas of interest include arterial and venous interventions, vertebroplasty, hepatic
brachytherapy, and uterine fibroid embolization. He is
a member of the American College of Radiology and
the Society of Interventional Radiology.
Piedmont Health SeniorCare
offers services that enable elderly
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References:
Berrington de González A, Mahesh M, Kim K-P, et
al. Projected cancer risks from computed tomographic
scans performed in the United States in 2007. Arch
Intern Med. 2009; 169(22): 2071-2077.
Smith-Bindman R, Lipson J, Marcus R, et al. Radiation dose associated with common computed tomography examinations and the associated lifetime attributable risk of cancer. Arch Intern Med. 2009; 169(22):
2078-2086.
Now accepting participants!
For more information or to visit our
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Donna Gilchrist, at (336) 532-0000.
Boom NC.com 3.11
CT Scans: What are the Real Risks?
Women Between 45 - 55
Needed for Research Study
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