How Well Does Dual-energy CT with Fast Kilovoltage Switching Quantify CT Number and Iodine and Calcium Concentrations?
How Well Does Dual-energy CT with Fast Kilovoltage Switching Quantify CT Number and Iodine and Calcium Concentrations?
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DOI：
10.1016/j.acra.2017.11.002
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发表时间：
2018-04-01
影响因子：
4.8
通讯作者：
Teshima, Teruki
中科院分区：
文献类型：
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作者：
Ohira, Shingo;Karino, Tsukasa;Teshima, Teruki
基本原理和目标：由于了解双能CT扫描仪的性能以确定临床诊断是必要的，因此我们旨在评估使用快速千伏切换的双能CT定量测量的准确性。材料和方法：对16种参考材料进行定量测量（物理密度，0.965-1.550 g/cm（3）;杆直径，2.0-28.5 mm;碘浓度，2-15 mg/mL;和钙浓度，50-300 mg/mL）与不同的扫描设置，并将测量值与其理论值进行比较。对于高密度材料，在50、70和100 keV的虚拟单色图像中Hounsfield单位值的最大差异分别为-176.2、61.0和-35.2 HU，并且在短期和长期期间的标准偏差分别为11.1、6.1、6.2和6.1 HU。最大3.5 HU。在50和70 keV下，Hounsfield单位测量的准确性显著较高（P < 0.05），辐射输出较高，体模尺寸较小。对于碘（5 mg/mL，直径2 mm）和钙（300 mg/mL）材料，大型体模中碘和钙测量值的差异高达-2.6和-60.4 mg/mL，小型体模的差异有所改善。金属伪影减少软件改善了主观图像质量;然而，定量值被显著低估（P < 0.05）。（对于50、70和100 keV，分别为-49.5、-26.9和-15.3 HU;对于碘和钙浓度，分别为-1.0和-17 mg/mL）。定量测量的准确性可能会受到材料密度和物体尺寸、辐射输出、体模尺寸和金属材料存在的影响。
Rationale and Objectives: Because it is imperative for understanding the performance of dual-energy computed tomography scanner to determine clinical diagnosis, we aimed to assess the accuracy of quantitative measurements using dual-energy computed tomography with fast kilovoltage switching.Materials and Methods: Quantitative measurements were performed for 16 reference materials (physical density, 0.965-1.550 g/cm(3); diameter of rod, 2.0-28.5 mm; iodine concentration, 2-15 mg/mL; and calcium concentration, 50-300 mg/mL) with varying scanning settings, and the measured values were compared to their theoretical values.Results: For high-density material, the maximum differences in Hounsfield unit values in the virtual monochromatic images at 50, 70, and 100 keV were -176.2, 61.0, and -35.2 HU, respectively, and the standard deviations over short- and long-term periods were 11.1, 6.1, and 3.5 HU at maximum. The accuracy of the Hounsfield unit measurement at 50 and 70 keV was significantly higher (P < 0.05) with higher radiation output and smaller phantom size. The difference in the iodine and calcium measurements in the large phantom were up to -2.6 and -60.4 mg/mL for iodine (5 mg/mL with 2-mm diameter) and calcium (300 mg/mL) materials, and the difference was improved with a small phantom. Metal artifact reduction software improved subjective image quality; however, the quantitative values were significantly underestimated (P < 0.05) (-49.5, -26.9, and -15.3 HU for 50, 70, and 100 keV, respectively; -1.0 and -17 mg/mL for iodine and calcium concentration, respectively) compared to that acquired without a metal material.Conclusions: The accuracy of quantitative measurements can be affected by material density and the size of the object, radiation output, phantom size, and the presence of metal materials.