Weekly cCTA dose reports eliminate high-dose outliers

Weekly e-mailed dose reports for cardiac CT angiography (cCTA) prodded high-dose outliers among imaging staff to refine their protocols and ultimately reduced total average radiation dose, according to a study published in the August issue of Academic Radiology.

“The implementation of weekly e-mailed dose reports was an attempt to engage all stakeholders to explore the optimal dose reduction strategies in all patients,” explained Leif-Christopher Engel, MD, of Massachusetts General Hospital in Boston, and colleagues.

In an effort to keep pace with dose reduction techniques, Massachusetts General implemented a quality project for its cCTA service in 2009. This effort used specifically tailored protocols, low kVp technique, prospective ECG triggering and automated exposure control to reduce doses by 75 percent.

“Relatively high radiation doses are often cited as a counterargument to the use of cCTA,” wrote the authors. “However, at our institution we have demonstrated that [with] cCTA carefully performed using relatively simple and widely available default protocol recommendations, we can achieve routine cCTA doses with a median dose lower than that of an invasive diagnostic angiography or the most commonly used noninvasive modality, nuclear myocardial perfusion imaging.”

When it was noticed that a small percentage of studies were conducted with significantly higher doses, a real-time feedback system using emailed weekly dose reports was started. To evaluate the benefit of this intervention, Engel and colleagues conducted an analysis of 450 consecutive patients who underwent physician-supervised cCTA: 150 patients from a preintervention period of April to September 2011, 150 patients from a postintervention period of September 2011 to February 2012, and 150 from a late control group from September 2012 to January 2013. The late control group served to indicate whether dose reductions were maintained over time.

The analysis revealed that preintervention doses were an average of 4.1 mSv, while postintervention the average dose fell to 3.4 mSv, reported the authors. This improvement persisted during the late control period.

The number of high-dose outliers was reduced through the weekly feedback system. Prior to implementation, 88 percent of exams were less than 10 mSv, and postintervention this proportion increased to 97.3 percent. The proportion of exams that were less than 20 mSv rose from 98.7 percent preintervention to 100 percent postintervention.

“Continued follow-up at our site is under way to ensure that these results are maintained,” wrote the authors.