用AI自动找断层扫描旋转中心,精度超99%且抗噪能力强。
Tomo-center: an AI-based rotation-axis center finder for synchrotron micro- and nano-tomography

- 将中心定位转为二分类任务,结合预训练视觉模型与注意力机制。
- 平均误差低于1像素,投影数减少10倍仍保持稳定性能。
- 开源工具已集成到多个成像软件,适合科研人员日常使用。
在平行束同步辐射微/纳米断层扫描中,精确确定旋转轴位置是实现无伪影重建的前提。传统方法如Vo法依赖投影图特征,对低对比度或弱吸收样品易失效。本文提出一种基于学习的方法,将中心选择视为二分类问题,采用DINOv2预训练的视觉变压器,并结合基于注意力的多实例学习,端到端地在断层图像上进行微调。推理时,该算法对一组候选中心重建的断层图堆栈进行评估,以选出最优中心。我们在两个独立数据集上测试了该方法的估计精度,均实现平均绝对误差低于1像素。此外,在投影稀疏或噪声增强条件下也表现稳健:当投影数减少至1/10或背景扫描噪声系数(泊松噪声)增至10时,性能依然稳定。我们还通过可视化连续空间特征对分类任务的相对贡献,展示了方法的可解释性。该方法已作为开源命令行工具tomo-center发布,并集成至多个断层扫描软件包中,用于常规光束线实验支持。
原文摘要 · Abstract (English)
Accurate determination of the rotation-axis position is a prerequisite for artifact-free reconstruction in parallel-beam synchrotron micro-tomography. Traditional approaches such as Vo's method rely on sinogram features that can fail for low-contrast or weakly absorbing specimens. We present a learning-based method that treats center selection as a binary classification problem, using a DINOv2-pretrained vision transformer aggregated with attention-based multiple-instance learning, fine-tuned end-to-end on tomographic images. At inference time, the proposed algorithm was applied to a stack of tomograms reconstructed at a sweep of candidate centers to select the optimal center for reconstruction. We tested the estimation accuracy of the proposed method on two independent data sources and consistently achieved a mean absolute error of below 1 pixel. We also tested the method robustness to sparse or noisy acquisitions with the same datasets and demonstrated consistent performance when the number of projections was reduced by a factor of up to 10 or the blank scan factor of the underlying Poisson's noise was increased to 10. We also illustrated the interpretability of the proposed method by mapping out the relative contributions of continuous spatial features to the overall classification task. This method, delivered as tomo-center, an open-source command-line tool, has been integrated into several tomography software packages to assist experiments during the routine beamline operations.
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