BACKGROUND: Reducing tube voltage from 120 kV to 100 kV during noncontrast CT for the detection of coronary artery calcium reduces patient radiation exposure. OBJECTIVE: We investigated whether coronary calcium scoring by multidetector row CT can be performed at reduced tube current, resulting in lower radiation dose to the patient. METHODS: Sixty-six outpatients were scanned on the same visit by dual-source CT (DSCT) with a standard protocol (120 kVp, 150 mAs), followed by a scan with reduced tube current: 85 mAs for patients with body mass index (BMI) ≤ 30 kg/m(2) and weight ≤ 85 kg, and 120 mAs for patients with BMI > 30 kg/m(2) or weight > 85 kg. Low-dose scans were scored by an experienced reader blinded to the standard scan. RESULTS: Agatston scores (ASs) and calcium volume for standard versus low-dose scans were 236 ± 581 versus 234 ± 586 (P = 0.65, NS), and 189 ± 460 mm(3) versus 184 ± 455 mm(3) with excellent correlation (r = 1.0, P < 0.0001), and no significant difference (P = 0.14, NS). Effective radiation dose for the low-dose protocol (1.0 ± 0.2 mSv) was significantly lower than for the standard protocol (1.7 ± 0.2 mSv; P < 0.0001). Image noise was higher for the low-dose scan (18.8 ± 5.5 HU vs 15.2 ± 4.8 HU; P < 0.0001), but both were within target limits. CONCLUSION: Noncontrast CT for measurement of coronary artery calcium with lower tube current optimized for patient body size is equivalent to standard methods at 40% lower radiation dose, indicating that radiation dose can be lowered for coronary calcium scanning. Copyright Â
BACKGROUND: Reducing tube voltage from 120 kV to 100 kV during noncontrast CT for the detection of coronary artery calcium reduces patient radiation exposure. OBJECTIVE: We investigated whether coronary calcium scoring by multidetector row CT can be performed at reduced tube current, resulting in lower radiation dose to the patient. METHODS: Sixty-six outpatients were scanned on the same visit by dual-source CT (DSCT) with a standard protocol (120 kVp, 150 mAs), followed by a scan with reduced tube current: 85 mAs for patients with body mass index (BMI) ≤ 30 kg/m(2) and weight ≤ 85 kg, and 120 mAs for patients with BMI > 30 kg/m(2) or weight > 85 kg. Low-dose scans were scored by an experienced reader blinded to the standard scan. RESULTS: Agatston scores (ASs) and calcium volume for standard versus low-dose scans were 236 ± 581 versus 234 ± 586 (P = 0.65, NS), and 189 ± 460 mm(3) versus 184 ± 455 mm(3) with excellent correlation (r = 1.0, P < 0.0001), and no significant difference (P = 0.14, NS). Effective radiation dose for the low-dose protocol (1.0 ± 0.2 mSv) was significantly lower than for the standard protocol (1.7 ± 0.2 mSv; P < 0.0001). Image noise was higher for the low-dose scan (18.8 ± 5.5 HU vs 15.2 ± 4.8 HU; P < 0.0001), but both were within target limits. CONCLUSION: Noncontrast CT for measurement of coronary artery calcium with lower tube current optimized for patient body size is equivalent to standard methods at 40% lower radiation dose, indicating that radiation dose can be lowered for coronary calcium scanning. Copyright Â