Radiation dose plummets with addition of new tech

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 - radiation dose, CT

A team who showed that a quality initiative could cut coronary CT angiography (CCTA) radiation dose by half has continued to chip away at dose, this time through the adoption of newer technologies. Overall, they reported a 77 percent reduction in dose over a four-year period.

Kavitha M. Chinnaiyan, MD, of Beaumont Health System in Royal Oak, Mich., and colleagues provided the latest chapter from the Advanced Cardiovascular Imaging Consortium (ACIC), a statewide quality initiative sponsored by Blue Cross/Blue Shield of Michigan that includes 47 centers. ACIC uses a best-practice algorithm, educational programs and feedback to help centers reduce patients’ exposure to radiation during CCTA scans.

Previous studies demonstrated use of the intervention trimmed median radiation dose by 53 percent from a median dose-length product (DLP) of 1,493 mGy*cm to 697 mGy*cm in a one-year period. In another analysis, the initiative helped knock down inappropriate use of CCTA by 60 percent.

In their most recent work, they examined whether the reductions could be sustained over time and whether continuing education and the introduction of newer scanner technology would further reduce dose. Their findings were published online Aug. 7 in Circulation: Cardiovascular Imaging.  

Chinnaiyan et al used registry data from the 15 hospitals that collected radiation data for the study. It incorporated three periods: a control (May-June 2008, the end of the previous study); follow-up I (July 2008-June 2009, to assess continuing education) and follow-up II (July 2009-April 2011, to examine data collected at sites that adopted advanced technologies). Follow-up II educational material promoted newer scanning techniques.

Analyses included total radiation dose from all parts of the CCTA scan. The primary endpoint was radiation dose and the secondary endpoint was image quality.

During the entire study period, 11,901 patients received CCTA scans. Newer technologies introduced included a high-pitch helical CT scanner at one site; adaptive statistical iterative reconstruction at three sites; volumetric 320-slice CT at one site and prospective gating adopted at six sites.

There was no significant change in dose between the control and follow-up I period. But between follow-up I and II, they measured a 31 percent dose reduction, from 697 mGy*cm to 468 mGy*cm and 9.5 mSv to 6.6 mSv. The median DLP was 350 mGy*cm and 4.9 mSv by the end of the study.

They found no difference in scan quality between the control and follow-up I, and a drop from 94 percent to 92.7 percent in diagnostic quality scans between follow-up I and II. The authors attributed to the latter to clinicians being “willing to make the trade-off between ‘pretty pictures’ and diagnostic images for the sake of patient safety.”  

“Combined with the previously reported 53 percent reduction during the first study period of the CQI [continuous quality improvement], this represents a net 77 percent reduction of dose from July 2007 to April 2011. The achievement of a median DLP of 350 mGy*cm or 4.9 mSv (during the final bimonthly period) exceeded the goal of 10 mSv set during the maintenance period, primarily after adoption of newer technologies,” Chinnaiyan and colleagues wrote.

They noted out that their study was observational and couldn’t pinpoint when new technologies were adopted at all sites.