Completeness map evaluation demonstrated with candidate next-generation cardiac CT architectures
Completeness map evaluation demonstrated with candidate next-generation cardiac CT architectures
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DOI：
10.1118/1.3700172
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发表时间：
2012-05-01
期刊：
影响因子：
3.8
通讯作者：
Yu, Hengyong
中科院分区：
文献类型：
--
作者：
Liu, Baodong;Bennett, James;Yu, Hengyong
目的：在本报告中，作者介绍了完整性图的一般概念，作为评价给定CT系统设计（架构和扫描模式）采集数据完整性的一种手段。他们说明了效用的完整性地图应用的完整性地图的概念，一些候选人的CT系统设计，作为研究的一部分，以推进国家的最先进的心脏CT.Methods：为了以最佳的重建一个点内的一个体积的利益（VOI），所有可能的平面上的Radon变换通过该点应进行测量。作者量化了整个图像体积满足这种理想条件的程度。他们首先确定VOI中每个点的Radon完整性数，作为实际测量的可能平面的百分比。然后将完整性图定义为整个VOI的完整性数的3D矩阵。作者提出了算法来分析Radon空间中的投影数据集并计算固定点的完整性数，并将这些算法应用于他们正在评估的各种架构和扫描模式。在本报告中，作者考虑了四种选定的候选架构，采用不同的扫描模式，总共有五种系统设计方案。这些替代品中的每一个使用completeness map.Results进行评估：如果探测器的大小和锥角足够大，以覆盖整个心脏VOI，单源圆形扫描可以有>= 99%的完整性超过整个VOI。然而，只有中心z切片可以被精确地重建，这对应于100%的完整性。对于典型的单源架构，如果探测器被限制为40 mm的轴向尺寸，则螺旋扫描需要大约五次旋转以形成覆盖心脏VOI的精确重建区域，而三源螺旋扫描仅需要两次旋转，从而导致时间分辨率提高2.5倍。如果逆几何（IGCT）系统的源和探测器具有相同的轴向范围，并且轴向和跨轴方向上的源点间距足够小，则IGCT也可以形成心脏VOI的精确重建区域。如果VOI可以被X射线束在任何视图中覆盖，则复合循环扫描可以生成覆盖VOI.Conclusions的精确重建区域：完整性图评估为选择下一代心脏CT系统设计提供了有用的信息。所提出的完整性地图方法提供了一个实用的工具，用于分析复杂的扫描轨迹，其中一些复杂的系统设计的理论图像质量是不可能预测的，没有尚未开发的重建算法。(C)2012年美国医学物理学家协会。[http：//dx.doi.org/10.1118/1.3700172]
Purpose: In this report, the authors introduce the general concept of the completeness map, as a means to evaluate the completeness of data acquired by a given CT system design (architecture and scan mode). They illustrate the utility of completeness map by applying the completeness map concept to a number of candidate CT system designs, as part of a study to advance the state-of-the-art in cardiac CT.Methods: In order to optimally reconstruct a point within a volume of interest (VOI), the Radon transform on all possible planes through that point should be measured. The authors quantified the extent to which this ideal condition is satisfied for the entire image volume. They first determined a Radon completeness number for each point in the VOI, as the percentage of possible planes that is actually measured. A completeness map is then defined as a 3D matrix of the completeness numbers for the entire VOI. The authors proposed algorithms to analyze the projection datasets in Radon space and compute the completeness number for a fixed point and apply these algorithms to various architectures and scan modes that they are evaluating. In this report, the authors consider four selected candidate architectures, operating with different scan modes, for a total of five system design alternatives. Each of these alternatives is evaluated using completeness map.Results: If the detector size and cone angle are large enough to cover the entire cardiac VOI, a single-source circular scan can have >= 99% completeness over the entire VOI. However, only the central z-slice can be exactly reconstructed, which corresponds to 100% completeness. For a typical single-source architecture, if the detector is limited to an axial dimension of 40 mm, a helical scan needs about five rotations to form an exact reconstruction region covering the cardiac VOI, while a triple-source helical scan only requires two rotations, leading to a 2.5x improvement in temporal resolution. If the source and detector of an inverse-geometry (IGCT) system have the same axial extent, and the spacing of source points in the axial and transaxial directions is sufficiently small, the IGCT can also form an exact reconstruction region for the cardiac VOI. If the VOI can be covered by the x-ray beam in any view, a composite-circling scan can generate an exact reconstruction region covering the VOI.Conclusions: The completeness map evaluation provides useful information for selecting the next-generation cardiac CT system design. The proposed completeness map method provides a practical tool for analyzing complex scanning trajectories, where the theoretical image quality for some complex system designs is impossible to predict, without yet-undeveloped reconstruction algorithms. (C) 2012 American Association of Physicists in Medicine. [http://dx.doi.org/10.1118/1.3700172]