eCardioVascular Beat

Radiation dose reduction and monitoring

Jeff Robins, R.T. (R) (CV), M.B.A.

Manager, cardiovascular lab
Providence Portland Medical Center

In 2006 the state of Oregon began requiring providers to document the time it takes to perform a fluoroscopy, and to establish time benchmarks on two of the most common procedures. Exceeding those benchmarks would trigger a quality review.

The Providence Portland Medical Center cardiovascular lab took a more comprehensive approach, which was also adopted by Providence St. Vincent Medical Center. We collected three months of fluoroscopy times in a number of different procedural categories.

Based on those times, we calculated a mean and set the benchmark at two standard deviations from the mean. We believed that if we were required to record information for quality purposes, the measures should have some validity.

Fluoroscopy time is a poor indicator of dose, which fluctuates widely due to a number of variables, such as the patient’s size. For example, five minutes of fluoroscopy on a small patient results in a significantly different radiation dose than five minutes on a large patient.

In addition, there are a wide variety of procedures done in the cardiovascular lab, each with unique requirements. Where the state requires a benchmark for at least two commonly performed procedures, Providence’s Portland Service Area has set 28 benchmarks based upon procedure types.

Where some facilities have met the requirement by setting benchmarks at 30 minutes for diagnostic procedures and 60 minutes for interventional procedures, the Portland Service Area benchmarks by procedure category range from two to 42 minutes. We expected that approximately 2 percent of cases would be reviewed because the benchmark was exceeded, and this has been our experience.

Improving patient dose measures

The next phase will be to achieve a better measurement of patient dose. Since the requirement of fluoroscopy benchmarks became the standard, X-ray equipment manufacturers have installed dosimeters in the systems. At some point, all imaging systems within the cardiovascular labs in the Portland Service Area will have these dosimeters.

Each system provides estimated doses for two different applications. One is dose area product, or DAP, which reports the total dose a patient receives and accounts for field size, etc. The other is air kerma, which is a good determinant to estimate the patient skin dose.

As procedures become more complex, and therefore take longer, dose will continue to be an issue. Our goal is to set a dose benchmark that will trigger a follow-up with the patient to make sure no skin injury has resulted.

While it is believed such an injury would be very rare, it is important in those instances to treat the injury appropriately. This approach is being considered not only in the Portland Service Area, but throughout Providence Health & Services.

As the U.S. Food and Drug Administration continues to focus on radiation exposure, Providence is able to demonstrate its commitment to providing the best care possible to our patients who undergo these procedures.