Coronary artery calcium scoring using a reduced tube voltage and radiation dose protocol with dual-source computed tomography

BackgroundTechnical advances to minimize radiation exposure because of imaging are in accord with the “as low as reasonably achievable” principle.ObjectiveWe aimed to determine whether coronary calcium scoring (CCS) by multidetector CT at a tube voltage of 100 kVp yields comparable results to the standard 120-kVp protocol while reducing radiation dose.MethodsSixty consecutive outpatients were scanned with a dual-source CT scanner with both the120- and 100-kVp protocols. The calcium threshold was 130 Hounsfield units (HUs) for 120 kVp and 147 HU for 100 kVp, as determined from phantom data. All 100-kVp scans were scored by an experienced reader blinded to 120-kVp data.ResultsImage quality was comparable for 100- and 120- kVp scans. Mean Agatston scores for 100 and 120 kVp were 189 ± 484 and 189 ± 498 (P = 0.92), with perfect correlation (r = 1.0; P < 0.0001; 95% limits of agreement, -36 to 37; bias, 0.6). Mean coronary calcium volume scores for 100 and 120 kVp were 143 ± 370 mm3 and 149 ± 392 mm3 (P = 0.26), with perfect correlation (r = 1.0; P < 0.0001; 95% limits of agreement, -35 to 32 mm3; bias, -1.4 mm3). The mean absolute difference for Agatston scores between the protocols was 16.9, with excellent agreement (κ = 0.95; P < 0.0001). Mean effective radiation dose for the 100-kVp protocol was significantly lower (1.17 mSv versus 1.70 mSv; P < 0.0001).ConclusionA reduced tube current protocol using 100 kVp gives equivalent CCS results at reduced radiation exposure compared with a standard protocol at 120 kVp.