On Assignment for the University of Michigan medical school's Medicine at Michigan magazine. In this article for the Inside Scope section, I met with Dr. Nallamothu on the Ann Arbor campus to discuss his work on imaging.
Inside Scope
In the Clinic
Diagnosing the Diagnostics
New findings on radiation exposure from imaging tests
By Nikolas Charles
Fall 2009
The standard procedure for physicians when diagnosing illness is to confirm its presence with state-of-the- art tests. In today’s technologically advanced world of medicine, those tests often include imaging studies that utilize radiation. Now, after a recent study on the levels of exposure to radiation from such tests in the U.S., a change in protocols may be needed.
“We decided to research this topic because of the rise in medical imaging,” says Brahmajee K. Nallamothu, M.D. (Fellowship 2004), an author of the study who is a U-M associate professor of internal medicine and a staff cardiologist at the VA Ann Arbor Healthcare System. As a clinical researcher, Nallamothu recognized the need to examine the use of these tests on patients throughout their lifetime.
“Rarely do patients undergo a single examination,” he says. “If you have chest pain, for example, it’s likely that you’re going to get more than one test, such as a stress test and possibly a cardiac catheterization. We approached the research by asking: If a single test in one person has a certain associated risk and is raising concerns, how many of these tests are occurring or being repeated in the same patient over longer periods of time?”
“There are a number of studies showing that many physicians aren’t even aware of this issue,” adds Reza Fazel (M.D. 2001, Residency 2004), lead author of the study and a cardiologist at Emory University. The study also included colleagues at Yale, Columbia, Mayo and Johns Hopkins, and was published in the New England Journal of Medicine in August.
In the study, nearly 1 million adults age 18-64 from five health care markets across the U.S. were identified from United Healthcare claims data. The utilization data from this group from 2005-07 was used to estimate cumulative effective doses of radiation from imaging procedures. Exposures were estimated using the concept of effective dose, which is expressed in millisieverts and reflects how harmful a given exposure is to the body.
Computed tomography (CT) scans were among the procedures exposing patients to the largest amounts of radiation. CT scans constituted only 16 percent of all procedures, but accounted for nearly 50 percent of the total exposure to patients.
Even before this study, the U-M was leading the charge to improve safety by justifying the use of each procedure, seeking alternative methods that might be safer, and minimizing radiation exposure during imaging.
Fazel and Nallamothu recommend that patients take an active role in reducing their risk by understanding why their physician is recommending a procedure, asking if there are safer alternatives, and requesting that the facility providing the imaging be certified for safe operating procedures.
Nallamothu stresses that imaging tests are a vital, lifesaving part of medical care. “Our study isn’t about eliminating imaging tests,” he says. “It’s about using them better — that is, only when necessary and in the best manner possible to reduce the risks to patients.”