Digital tomosynthesis (DTS) technology has attracted much attention in the field of nondestructive testing of printed circuit boards (PCB) due to its high resolution and suitability to thin slab objects. However, the traditional DTS iterative algorithm is computationally demanding, and its real-time processing of high-resolution and large volume reconstruction is infeasible. To address this issue, we in this study propose a multiple multi-resolution algorithm, including two multi-resolution strategies: volume domain multi-resolution and projection domain multi-resolution. The first multi-resolution scheme employs a LeNet-based classification network to divide the roughly reconstructed low-resolution volume into two sub-volumes namely, (1) the region of interest (ROI) with welding layers that necessitates high-resolution reconstruction, and (2) the remaining volume with unimportant information which can be reconstructed in low-resolution. When X-rays in adjacent projection angles pass through many identical voxels, information redundancy is prevalent between the adjacent image projections. Therefore, the second multi-resolution scheme divides the projections into non-overlapping subsets, using only one subset for each iteration. The proposed algorithm is evaluated using both the simulated and real image data. The results demonstrate that the proposed algorithm is approximately 6.5 times faster than the full-resolution DTS iterative reconstruction algorithm without compromising image reconstruction quality.

中文翻译：

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基于多重多分辨率重建算法的印刷电路板快速断层合成方法

数字断层合成（DTS）技术因其高分辨率和适用于薄板物体而在印刷电路板（PCB）无损检测领域备受关注。然而，传统的DTS迭代算法计算量大，无法实时处理高分辨率、大体积的重建。为了解决这个问题，我们在本研究中提出了一种多重多分辨率算法，包括两种多分辨率策略：体积域多分辨率和投影域多分辨率。第一个多分辨率方案采用基于 LeNet 的分类网络将粗略重建的低分辨率体积分为两个子体积，即（1）具有需要高分辨率重建的焊接层的感兴趣区域（ROI），以及（2）剩余的不重要信息的体积，可以低分辨率重建。当相邻投影角度的 X 射线穿过许多相同的体素时，相邻图像投影之间普遍存在信息冗余。因此，第二种多分辨率方案将投影划分为不重叠的子集，每次迭代仅使用一个子集。使用模拟和真实图像数据评估所提出的算法。结果表明，该算法比全分辨率 DTS 迭代重建算法快约 6.5 倍，且不影响图像重建质量。