Department of Biomedical Sciences and Biomedical Imaging Research Institute, Cedars-Sinai Medical Center, 8700 Beverly Boulevard, Room A238, Taper Building, Los Angeles, CA 90048, USA.
J Cardiovasc Comput Tomogr. 2012 Mar-Apr;6(2):113-20. doi: 10.1016/j.jcct.2011.12.008. Epub 2012 Jan 28.
Reducing tube voltage from 120 kV to 100 kV during noncontrast CT for the detection of coronary artery calcium reduces patient radiation exposure.
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.
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.
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.
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.
在非对比 CT 中，将管电压从 120kV 降低到 100kV 可以降低冠状动脉钙的患者放射暴露。
我们研究了多排螺旋 CT（MDCT）是否可以在降低管电流的情况下进行冠状动脉钙评分，从而降低患者的放射剂量。
66 例门诊患者在同一时间接受双源 CT（DSCT）扫描，采用标准方案（120kVp，150mAs），然后进行管电流降低扫描：BMI≤30kg/m2 且体重≤85kg 的患者采用 85mAs，BMI>30kg/m2 或体重>85kg 的患者采用 120mAs。低剂量扫描由一位对标准扫描不知情的经验丰富的读者进行评分。
标准扫描与低剂量扫描的 Agatston 评分（AS）和钙体积分别为 236±581 与 234±586（P=0.65，NS），189±460mm3 与 184±455mm3 相关性极好（r=1.0，P<0.0001），无显著差异（P=0.14，NS）。低剂量方案的有效放射剂量（1.0±0.2mSv）明显低于标准方案（1.7±0.2mSv；P<0.0001）。低剂量扫描的图像噪声更高（18.8±5.5HU 与 15.2±4.8HU；P<0.0001），但均在目标范围内。
针对患者体型优化的低管电流非对比 CT 冠状动脉钙测量与标准方法等效，但放射剂量降低 40%，表明可以降低冠状动脉钙扫描的放射剂量。
