Optimized imaging protocols reduce radiation dose during wrist CT examinations

Following optimized CT protocols during wrist examinations can lead to significant reductions in radiation dose, according to a case study published in the Journal of the American College of Radiology.

“Decreasing radiation dose to patients is an important and apropos topic in this era of rapidly growing medical imaging volumes,” wrote Hythem Omar, MD, department of radiology at UT Southwestern Medical Center in Dallas, Texas, and colleagues.

The authors used a cadaver wrist to determine how low the estimated radiation dose could get while still delivering a clinically acceptable image quality, imaging it on three of their institution’s CT scanners at 80, 100 and 120 kVp. Two musculoskeletal radiologists blinded to the peak kilovolt setting then reviewed the images and rated the quality using a five-point Likert scale. A score of three or higher was viewed as acceptable, and the team used those scores to determine the lowest allowable kilovoltage for each of the three scanners.

An institutional physics team, led by an experienced medical physicist, was also brought in to evaluate the CT equipment as needed and help ensure the institution’s scanners were all accurate and speaking the same language in term of signal-to-noise ratio and contrast-to-noise ratio.

“This was to ensure that the same estimated dose would be delivered by each scanner,” the authors wrote. “After these setting changes were made, routine CT wrist examinations were performed per clinical request using the optimized protocols.”

Omar et al. then compared 50 consecutive wrist CT examinations performed from Dec. 14, 2013, to Nov. 26, 2014 (before dose optimization) with 60 consecutive wrist CT examinations performed between Jan. 23, and Dec. 9, 2015 (after dose optimization). Overall, volume CT dose index (CTDIvol) and dose length product (DLP) both saw a “significant decrease.” Median CTDIvol dropped 56 percent, and mean CTDIvol dropped 60 percent. Median DLP dropped 50 percent, and mean DLP dropped 44 percent.

“Our project effectively standardized CT scanning parameters for examinations of the wrist across institutional campuses consisting of various scanner makes and models,” the authors concluded. “It resulted in significant dose reduction while maintaining diagnostic accuracy and quality of scans. Such quality projects potentially set examples for other hospitals and imaging centers to reduce patients’ exposure to ionizing radiation.”