fluoroscopy and nuclear medicine studies
make up only 26 percent of imaging procedures using radiation, they contribute
89 percent of the total yearly exposure to
radiation.
CT scans in particular have attracted
attention because they’ve become the tool
of first choice in diagnosing many conditions, even though they use large amounts
of ionizing radiation, which can cause genetic damage to cells and increase the risk
of cancer. As an example of the increased
reliance on CT scans, a study from the
University of Michigan, released last year,
found that nationally the rate of CT use
in emergency departments grew 11 times
faster than the rate of ED visits between
1996 and 2007.
Many observers believe other states will
follow California’s example, and multiple
national campaigns are aimed at reducing
medical radiation exposure. Last year the
American Medical Association adopted a
resolution that supports tracking imaging
procedures in EHRs to help physicians dis-
cuss radiation exposure issues with their
patients. Also last year, the Joint Commis-
sion issued an alert urging providers to use
diagnostic radiation carefully and issued a
series of recommendations, including :
• Using imaging techniques other than
CT, such as ultrasound or magnetic reso-
nance imaging (MRI), and fostering col-
laboration between radiologists and refer-
ring physicians about the appropriate use
of diagnostic imaging.
• Expanding the radiation safety officer’s role to explicitly include patient safety
as it relates to radiation and dosing, as well
as education on proper dosing and equipment usage for all physicians and technologists who prescribe diagnostic radiation
or use diagnostic radiation equipment.
Increasingly, I.T. staff in facilities that
perform CT scans may be asked to partici-
pate in initiatives to capture and record ra-
diation doses, provide radiation exposure
history as a routine part of the electronic
health record, and participate in national
dose registries designed to help deter-
mine how well the facility is optimizing its
use of radiation. At the same time, the CT
scanners will benefit from new advances
in software that allow more sophisticated
image analysis and can further cut the
dose of radiation needed to produce a di-
agnostic-quality image.
Why track?
It may seem obvious that excess radiation exposure is bad—after all, it’s well established
that a summer afternoon without sunscreen
can produce a severe burn, and too many
of those summer afternoons can lead to
melanoma later in life. But what constitutes
“excess” in a medical context? Aside from
extreme overexposure, where the damage is
immediately obvious, measuring the risks of
medical radiation is difficult at best.
“The science behind long-term harm
from medical radiation is weak for many dif-
ferent reasons,” says Rohit Inamdar, senior
medical physicist at ECRI Institute, Plym-
outh Meeting, Pa., which offers CT radiation
dose safety reviews among its consulting
services for health care providers. “We don’t
have the ability to look at a cancer and say
what caused it.”
The best long-term radiation exposure
data available currently comes from the sur-
vivors of the atom bombs dropped on Hiro-
shima and Nagasaki in World Ward II. Inam-
dar calls the comparison of medical patients
with atom bomb survivors “questionable,”
even though some patients who require
many CT scans over a relatively short pe-
riod may be exposed to more radiation than
some atom bomb survivors.
“Personally, I think cumulative dose
is important, but we don’t have the tools
to measure it, and I don’t think we will for
many years,” Inamdar says.
Richard Morin, chair of the Dose Index
Registry for the American College of Radi-
ology and a medical physicist at the Mayo
Clinic Jacksonville, says getting clean data
on long-term CT radiation risks is almost
impossible—let alone comparing those
risks with the short-term benefit of having
an otherwise appropriate CT scan. “The
idea of some magic number that would
cause [cancer] doesn’t make any sense,”
he says.
Cumulative risk
Rebecca Smith-Bindman at UCSF disagrees. “No other risk factor for cancer
has been studied the way radiation has,”
she said, pointing to a June Lancet
article showing a tripled risk of leukemia
and brain cancer for people who had
received CT scans as children between
1985 and 2002.
She says the idea of cumulative risk of
cancer is well established for other factors,
such as cigarette smoking, and radiation
has been shown to damage cells and their
genetic material. And to extend the driving
analogy, Smith-Bindman points out that
roads and cars are both heavily engineered
to minimize the risk of accidents.
Everyone agrees that CT imaging should
be done at the lowest radiation dose that
yields an adequate image for diagnosis.
And there’s general agreement also that
the medical benefit of an appropriate imaging procedure at the lowest achievable
