ACR Dose Index Registry - One Institution’s Experience

CHICAGO - In late 2011, a group of radiology faculty and staff at Emory HealthCare and the School of Medicine decided to join the American College of Radiology’s Dose Index Registry in an effort to control and standardize their dose rates. The results, school officials say, is a system-wide drop in dose.

As registry members, Emory officials submitted anonymized CT data to the ACR and received a report, showing how the institution’s dose practices compare to its peer facilities. According to Brent Little, MD, assistant professor radiology and radiology residency director for cardiothoracic imaging, the radiology department designed an experiment to see if they could use this knowledge to make a positive change with CT scans.

“Uniform dose is a particularly poignant point for institutions with a large number of scanners, such as Emory. It’s important that patients get a uniform dose across all scanners,” Little said this week at RSNA 2013. “And, we saw significant differences in dose even within the same scanner - sometimes with the same patient, in the same scanner, with the same operator.”

Consequently, the radiology department opted to analyze dose reports from seven out of the University’s 25 CT scanners. The selected machines reflected a wide variety of vendors and platforms, he said.

Using the many charts and graphs based on Emory’s data that the ACR provided, the radiology department was able to pinpoint the cases where dose was higher or lower than anticipated and determine what positive changes could be made. This work ultimately revealed that, for chest CT scans, Emory achieved a 29 percent mean reduction among its scanners. The mean dose reductions for head CT with contrast and abdominal/pelvis CT with contrast were 35 percent and 26 percent, respectively. Chest CT with contrast saw a 17 percent dose drop.

How Emory Achieved Its Results

The Dose Index Registry might have highlighted where Emory needed to improve, but the institution had to take several steps to make its dose reductions a reality. And, these strategies can be easily implemented in other facilities, Little said.

1. Over-coverage: It’s likely that you read plenty of scans that include images of body parts that hold no interest to you. For example, a CT scan of the lower abdomen could include a significant amount of the upper abdomen. Capturing that part of the body in a study adds nothing to the diagnosis, but it does add to the dose rate. Tightening up your field of view could make a significant dent in the radiation your patients encounter.

2. Iterative reconstruction: Don’t shy away from using iterative reconstruction software. This tool lets you capture lower-dose images with higher noise and, then, runs the images through a processor to strengthen the image quality.

3. Manual settings: Take a look at your scanner settings, and if your scanner has it, switch it to dose-saving settings. That will enable your machine to more aggressively target dose. Also, when it’s appropriate, automate or manually reduce the tube potential.

It might take a while for your scanners to standardize, and it’s likely that you’ll never reach the point where every scanner will provide a uniform dose for every scan with every patient, he said. But, ultimately, he said, it’s the effort to make the change that’s important.

“Remember that the journey you take is the important thing. You can determine how best to use the dose registry to help with your dose tracking and modification,” Little said. “Don’t be discouraged because you won’t get uniform reductions across all your scanners. Be encouraged by the successes that you do have.”