Third-generation CT systems offer quality images at lower dose

Third-generation CT scanners have been shown to be capable of generating high-quality contrast images while delivering lower doses of ionizing radiation than their predecessors, according to a study published in Radiology.

Authored by Mathias Meyer, MD, of the Institute of Clinical Radiology and Nuclear Medicine at the University Medical Center Mannheim, Germany, and colleagues, the study set out to examine a new generation of CT scanner technology that operates at a lower voltage.

“The hypothesis of our study was that a 70 kV protocol would enable us to lower the amount of contrast medium and radiation exposure while maintaining or even improving vessel contrast,” Meyer and colleagues wrote.

The team evaluated radiation and contrast medium requirements for performing high-pitch coronary CT angiography at 70 kV using a third-generation dual source CT system in comparison to a second-generation dual-source CT system.

The study examined 45 patients, 27 men and 18 women, and all examinations were done with either a third-generation scanner at 70 kV or second-generation CT scanner at 80 or 100 kV.

Researchers found the signal-to-noise ratio of the coronary CT angiography studies acquired with third-generation CT system was significantly higher than those acquired with the other two protocols for all coronary arteries.

Qualitative image quality analyses revealed no significant differences between the three CT angiography protocols

“In this study, coronary CT angiography at 70 kV with a third-generation dual-source CT system provided excellent image quality over wider ranges of heart rates while significantly lowering radiation dose exposure and contrast medium amount as compared with previous second-generation dual-source CT coronary CT angiography protocols,” Meyer and colleagues wrote.

Meyer and his team found that with the recent arrival of third generation dual-source CT systems, routine 70 kV coronary CT angiography imaging studies have become viable because of two integrated x-ray tubes capable of generating a peak tube current 1300 mA—which results in radiation dose reduction of 52 percent compared to the 80 kV coronary CT angiography associated with second-generation dual-source CT.

An additional advantage linked to lower tube voltage of the third-generation CT system is reduced contrast medium requirements.

“This may be important as invasive and noninvasive cardiac procedures utilizing contrast media are steadily increasing, which, according to some, renders contrast medium–induced nephropathy the third leading cause of hospital-acquired acute kidney injury,” researchers wrote.