The scanner could be brand new, but there is a good chance it’s operating with old protocols imported from a previous unit and not optimized for best imaging at the reduced dose levels possible today, a researcher suggests.
Outdated CT protocols are a widespread problem, according to Dr. Aaron Sodickson, assistant director of emergency radiology at Brigham and Women’s Hospital in Boston, Massachusetts.
“Many practices don’t take full advantage of available dose-reduction tools,” he said in an interview about his presentation at the American Roentgen Ray Society meeting. “There have been great advances in CT technology that enable reduction in radiation exposure while still getting high-quality images. But because of all these advances, people have a hard time keeping up.”
Each practice needs a local champion responsible for protocol oversight and optimization, but they can only do that with the right information, he said.
“They need information from the manufacturer about what the available tools are and how to make the best use of them,” he said.
CT protocols are often ported from older scanners to newer scanners essentially unchanged, which may result in unnecessary radiation exposure for patients. Optimal scan acquisition is the radiologist’s responsibility, and there are several steps radiologists can take to dose-optimize their CT protocols, Sodickson said in his presentation.
General strategies radiologists can implement include:
• Use size-dependent protocols;
• Understand and enable dose-reduction tools;
• Reduce the number of passes through a body region;
• Reduce duplicate or overlapping coverage;
• Reduce mAs for high-contrast imaging;
• Optimize IV contrast infusion timing; and
• Lower kVp if patient size allows.
The most important of these is size-dependent protocols, Sodickson said. Good-quality images can be obtained with many fewer x-rays in small patients than in large patients, so scan techniques must be adapted to patient size. Most modern scanners include robust tube current modulation methods to adjust the x-ray output according to patient size, but the tools must be enabled and properly used. These tools not only adjust to overall size differences, but can also account for variations during the course of the scan. Certain body regions, like the chest, contain less tissue to attenuate x-rays, which allows a reduction in x-ray tube output while still maintaining good diagnostic-quality images.
