Variability in CT lung-nodule volumetry: Effects of dose reduction and reconstruction methods
Variability in CT lung-nodule volumetry: Effects of dose reduction and reconstruction methods
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DOI：
10.1118/1.4918919
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发表时间：
2015-05-01
期刊：
影响因子：
3.8
通讯作者：
McNitt-Gray, Michael F.
中科院分区：
文献类型：
--
作者：
Young, Stefano;Kim, Hyun J. Grace;McNitt-Gray, Michael F.
目的：测量胸部CT上结节的大小对肺癌分期和衡量治疗效果具有重要意义。3D容量法已被提出作为1D和2D尺寸测量方法的更稳健的替代方法。在降低CT辐射剂量的方法方面也取得了实质性进展。这项工作的目的是研究剂量减少和重建方法对3D肺结节volumetry.Methods的变异性的影响：减少剂量CT扫描模拟应用噪声添加工具的原始（正弦图）数据从临床上表明患者扫描上获得的multidetector-row CT扫描仪（定义闪存，西门子医疗）。在其临床方案剂量的25%、10%和3%（CTDIvol为20.9 mGy）下模拟扫描，对应CTDIvol值为5.2、2.1和0.6 mGy。采用传统的滤波反投影（B45核）和迭代重建方法（SAFIRE：I44强度3和I50强度3）重建模拟的降低剂量数据。在盲法研究设计中，三名实验室技术员阅片员在每种不同的采集/重建条件下对33名患者的“可测量”结节进行轮廓勾画。在33个可测量的结节中，17个用于估计其临床参考方案的重复性，以及剂量间和重建方法间的重现性。作者通过分析其平均值，标准差（SD），t-检验和F-检验result.Results：临床剂量重复性实验产生的平均比例差异为1.1%，SD为5.5%，跨剂量和重建方法的比例差异的分布进行了比较。剂量间重现性实验得出的平均差异范围为-5.6%至-1.7%，SD范围为6.3%至9.9%。重建方法间重现性实验得出的平均差异为2.0%（I44规格3）和-0.3%（I50规格3），SD相同，为7.3%。对于重复性病例子集，I44强度3和I50强度3的重建方法间平均值/SD对分别为（1.4%，6.3%）和（-0.7%，7.2%）。代表性结节的分析证实，读者的变异性出现不受剂量或重建method.Conclusions：肺结节体积测定是非常强大的辐射剂量水平，下降到最低扫描仪支持的剂量设置。此外，容量测定法对本研究中使用的重建方法具有稳健性，包括传统的滤波反投影和迭代方法。(C)2015年美国医学物理学家协会。
Purpose: Measuring the size of nodules on chest CT is important for lung cancer staging and measuring therapy response. 3D volumetry has been proposed as a more robust alternative to 1D and 2D sizing methods. There have also been substantial advances in methods to reduce radiation dose in CT. The purpose of this work was to investigate the effect of dose reduction and reconstruction methods on variability in 3D lung-nodule volumetry.Methods: Reduced-dose CT scans were simulated by applying a noise-addition tool to the raw (sinogram) data from clinically indicated patient scans acquired on a multidetector-row CT scanner (Definition Flash, Siemens Healthcare). Scans were simulated at 25%, 10%, and 3% of the dose of their clinical protocol (CTDIvol of 20.9 mGy), corresponding to CTDIvol values of 5.2, 2.1, and 0.6 mGy. Simulated reduced-dose data were reconstructed with both conventional filtered backprojection (B45 kernel) and iterative reconstruction methods (SAFIRE: I44 strength 3 and I50 strength 3). Three lab technologist readers contoured "measurable" nodules in 33 patients under each of the different acquisition/reconstruction conditions in a blinded study design. Of the 33 measurable nodules, 17 were used to estimate repeatability with their clinical reference protocol, as well as interdose and inter-reconstruction-method reproducibilities. The authors compared the resulting distributions of proportional differences across dose and reconstruction methods by analyzing their means, standard deviations (SDs), and t-test and F-test results.Results: The clinical-dose repeatability experiment yielded a mean proportional difference of 1.1% and SD of 5.5%. The interdose reproducibility experiments gave mean differences ranging from -5.6% to -1.7% and SDs ranging from 6.3% to 9.9%. The inter-reconstruction-method reproducibility experiments gave mean differences of 2.0% (I44 strength 3) and -0.3% (I50 strength 3), and SDs were identical at 7.3%. For the subset of repeatability cases, inter-reconstruction-method mean/SD pairs were (1.4%, 6.3%) and (-0.7%, 7.2%) for I44 strength 3 and I50 strength 3, respectively. Analysis of representative nodules confirmed that reader variability appeared unaffected by dose or reconstruction method.Conclusions: Lung-nodule volumetry was extremely robust to the radiation-dose level, down to the minimum scanner-supported dose settings. In addition, volumetry was robust to the reconstruction methods used in this study, which included both conventional filtered backprojection and iterative methods. (C) 2015 American Association of Physicists in Medicine.