When good habits go bad

May 1, 2009

Habits run our lives. Some are good. We reach to the left of a faucet when we want warm water and to the right for cold; slam on the brakes when a ball skitters from a playground into the road; tie our shoes when they come undone. But not all habits are good, and even ones that have served us well can go wrong if they don’t evolve.

Habits run our lives. Some are good. We reach to the left of a faucet when we want warm water and to the right for cold; slam on the brakes when a ball skitters from a playground into the road; tie our shoes when they come undone. But not all habits are good, and even ones that have served us well can go wrong if they don't evolve.

This is the lesson to be learned at the American Roentgen Ray Society meeting this week, one that specifically addresses radiation exposure to patients, particularly from CT.

A study performed at the Carilion Clinic in Roanoke, VA, found that the majority of ordering physicians underestimate the radiation dose of abdominal-pelvic CTs and that only a small minority advise patients of the risk from the exam. One way to begin remedying this problem, according to the presenters, is to make radiation education part of the training given to medical students and residents, as well as to practicing physicians through institutional conferences and workshops.

Along with the risks associated with radiation exposure should be a strong dose of reality in what advanced imaging technologies can -- and cannot -- do. Researchers at Staten Island University Hospital in New York argued in their ARRS presentation that the number of unnecessary exams involving CT, MR, and nuclear medicine could be cut significantly by educating referring docs to the risks and benefits of and alternatives to various imaging modalities. Their study found that targeted education of referring clinicians led to a 26% reduction in the number of advanced radiologic studies ordered, including an 18% reduction of in the number of ordered CT exams. The end result was reduced financial costs and less patient exposure to radiation.

This risk can be cut in ways that do not cut CT out of the picture. Researchers at Cleveland Clinic Children's Hospital in Ohio noted that adjusting kVp (kilovoltage peak) and mAs (tube current flow) according to a patient's body shape can substantially reduce pediatric exposure to radiation. Studies using phantoms of varying diameter demonstrated the importance of adjusting CT operating parameters to suit body shape rather than age of the child, the more common approach.

Sometimes the resources at hand play a role in minimizing patient dose. This is true when managing pregnant patients who must undergo CT, according to researchers at State University New York Stony Brook University Medical Center. They found that 64-slice scanners should be used when CT is indicated in the assessment of pregnant patients for possible pulmonary emboli (PE). These scanners present less risk to the fetus, according to the research, due to be presented at ARRS 2009, because they deliver dose more efficiently than lesser slice scanners. Knowing the advantages of 64-slice scanners is important, the team said, because pregnant patients are at great risk for PE and pulmonary angiograms are often needed to assess symptoms indicating this problem.

But exams that use ionizing radiation are not always necessary. ARRS presenters from the University of Virginia in Charlottesville this week will present data showing that MR is a safe and accurate tool for diagnosing appendicitis in pregnant patients and that MR is also effective in evaluating and guiding the treatment of patients with Crohn's disease, a common inflammatory bowel disorder.

It all comes down to using the right tool for the job. This week's ARRS meeting offers up a treasure trove of documented findings that, if applied, could translate into better medical practices. In a cost-constrained market increasingly sensitized to patient-dose issues, there has been no better time for these kinds of studies.