使用 320 排容积扫描仪进行单次心跳冠状动脉 CT 血管造影的辐射剂量。
Radiation dose from single-heartbeat coronary CT angiography performed with a 320-detector row volume scanner.
机构信息
Department of Medicine, Cardiology Division, Department of Radiology, and Center for Radiological Research, Columbia University Medical Center and New York-Presbyterian Hospital, 622 W 168th St, PH 10-203A, New York, NY 10032, USA.
出版信息
Radiology. 2010 Mar;254(3):698-706. doi: 10.1148/radiol.09090779.
PURPOSE
To determine radiation doses from coronary computed tomographic (CT) angiography performed by using a 320-detector row volume scanner and evaluate how the effective dose depends on scan mode and the calculation method used.
MATERIALS AND METHODS
Radiation doses from coronary CT angiography performed by using a volume scanner were determined by using metal-oxide-semiconductor field-effect transistor detectors positioned in an anthropomorphic phantom physically and radiographically simulating a male or female human. Organ and effective doses were determined for six scan modes, including both 64-row helical and 280-row volume scans. Effective doses were compared with estimates based on the method most commonly used in clinical literature: multiplying dose-length product (DLP) by a general conversion coefficient (0.017 or 0.014 mSv.mGy(-1).cm(-1)), determined from Monte Carlo simulations of chest CT by using single-section scanners and previous tissue-weighting factors.
RESULTS
Effective dose was reduced by up to 91% with volume scanning relative to helical scanning, with similar image noise. Effective dose, determined by using International Commission on Radiological Protection publication 103 tissue-weighting factors, was 8.2 mSv, using volume scanning with exposure permitting a wide reconstruction window, 5.8 mSv with optimized exposure and 4.4 mSv for optimized 100-kVp scanning. Estimating effective dose with a chest conversion coefficient resulted in a dose as low as 1.8 mSv, substantially underestimating effective dose for both volume and helical coronary CT angiography.
CONCLUSION
Volume scanning markedly decreases coronary CT angiography radiation doses compared with those at helical scanning. When conversion coefficients are used to estimate effective dose from DLP, they should be appropriate for the scanner and scan mode used and reflect current tissue-weighting factors. (c) RSNA, 2010.
目的
使用 320 排容积扫描仪确定冠状动脉 CT 血管造影术（CCTA）的辐射剂量，并评估有效剂量如何取决于扫描模式和使用的计算方法。
材料与方法
使用放置在物理和放射学上模拟男性或女性人体的金属氧化物半导体场效应晶体管探测器，在体模中确定使用容积扫描仪进行的 CCTA 的辐射剂量。为包括 64 排螺旋和 280 排容积扫描在内的 6 种扫描模式确定了器官和有效剂量。比较了基于临床文献中最常用的方法（将剂量长度乘积（DLP）乘以一般转换系数（0.017 或 0.014 mSv·mGy-1·cm-1））和基于单层面扫描仪和先前组织权重因子的胸部 CT 蒙特卡罗模拟确定的有效剂量的估计值。
结果
与螺旋扫描相比，容积扫描可使有效剂量降低 91%，同时保持相似的图像噪声。使用国际辐射防护委员会第 103 号出版物中的组织权重因子，在允许广泛重建窗的曝光条件下使用容积扫描时，有效剂量为 8.2 mSv，在优化曝光条件下为 5.8 mSv，在优化 100 kVp 扫描条件下为 4.4 mSv。使用胸部转换系数估计有效剂量时，剂量低至 1.8 mSv，但会大大低估容积和螺旋 CCTA 的有效剂量。
结论
与螺旋扫描相比，容积扫描可显著降低 CCTA 的辐射剂量。当使用 DLP 来估计有效剂量时，转换系数应适用于所使用的扫描仪和扫描模式，并反映当前的组织权重因子。（放射学学会，2010 年）
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