University Institute of Diagnostic, Interventional and Pediatric Radiology, University Hospital Bern, University of Bern, Freiburgstrasse 10, CH-3010 Bern, Switzerland.
Radiology. 2011 Aug;260(2):454-62. doi: 10.1148/radiol.11102217. Epub 2011 Apr 14.
To assess the diagnostic accuracy, image quality, and radiation dose of an iterative reconstruction algorithm compared with a filtered back projection (FBP) algorithm for abdominal computed tomography (CT) at different tube voltages.
A custom liver phantom with 45 simulated hypovascular liver tumors (diameters of 5, 10, and 15 mm; tumor-to-liver contrast of 10, 25, and 50 HU) was placed in a cylindrical water container that mimicked an intermediate-sized patient. The phantom was scanned at 120, 100, and 80 kVp. The CT data sets were reconstructed with FBP and iterative reconstruction. The image noise was measured, and the contrast-to-noise ratio (CNR) of the tumors was calculated. The radiation dose was assessed with the volume CT dose index. Tumor detection was independently performed by three radiologists. Statistical analysis included analysis of variance.
Compared with the FBP data set at 120 kVp, the iterative reconstruction data set collected at 100 kVp demonstrated significantly lower mean image noise (20.9 and 16.7 HU, respectively; P < .001) and greater mean CNRs for the simulated tumors (P < .001). The iterative reconstruction data set collected at 120 kVp yielded the highest sensitivity for tumor detection, while the FBP data set at 80 kVp yielded the lowest. The sensitivity for the iterative reconstruction data set at 100 kVp was comparable with that for the FBP data set at 120 kVp (79.3% and 74.9%, respectively; P > .99). The volume CT dose index decreased by 39.8% between the 120-kVp protocol and the 100-kVp protocol and by 70.3% between the 120-kVp protocol and the 80-kVp protocol.
Results of this phantom study suggest that a 100-kVp abdominal CT protocol with an iterative reconstruction algorithm for simulated intermediate-sized patients increases the image quality and maintains the diagnostic accuracy at a reduced radiation dose when compared with a 120-kVp protocol with an FBP algorithm.
评估与滤波反投影（FBP）算法相比，迭代重建算法在不同管电压下进行腹部 CT 检查的诊断准确性、图像质量和辐射剂量。
在一个圆柱形水容器中放置一个具有 45 个模拟低血管性肝肿瘤的定制肝体模（直径为 5、10 和 15mm；肿瘤与肝脏对比度为 10、25 和 50HU），该体模模拟了一个中等体型的患者。对体模分别在 120、100 和 80kVp 下进行扫描。使用 FBP 和迭代重建对 CT 数据集进行重建。测量图像噪声，并计算肿瘤的对比噪声比（CNR）。使用容积 CT 剂量指数评估辐射剂量。三位放射科医生独立进行肿瘤检测。统计分析包括方差分析。
与 120kVp 的 FBP 数据集相比，100kVp 的迭代重建数据集的平均图像噪声显著降低（分别为 20.9 和 16.7HU；P＜0.001），模拟肿瘤的平均 CNR 也显著增加（P＜0.001）。120kVp 的迭代重建数据集的肿瘤检测敏感性最高，而 80kVp 的 FBP 数据集的肿瘤检测敏感性最低。100kVp 的迭代重建数据集的敏感性与 120kVp 的 FBP 数据集相当（分别为 79.3%和 74.9%；P＞0.99）。120kVp 方案与 100kVp 方案相比，容积 CT 剂量指数降低了 39.8%，与 120kVp 方案相比，容积 CT 剂量指数降低了 70.3%。
这项体模研究的结果表明，对于模拟的中等体型患者，100kVp 腹部 CT 协议联合迭代重建算法可提高图像质量，并在降低辐射剂量的情况下保持与 120kVp 协议联合 FBP 算法相当的诊断准确性。
