Image quality and scan time optimisation for in situ phase contrast x-ray tomography of the intervertebral disc
Image quality and scan time optimisation for in situ phase contrast x-ray tomography of the intervertebral disc
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DOI：
10.1016/j.jmbbm.2022.105579
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发表时间：
2022-12-01
影响因子：
3.9
通讯作者：
Lee, P. D.
中科院分区：
文献类型：
--
作者：
Disney, C. M.;Vo, N. T.;Lee, P. D.
在线相衬同步加速器断层扫描结合原位机械载荷，可以通过整个器官内的数字体积相关（DVC）来表征软组织微观力学。优化扫描时间对于减少多次扫描的辐射剂量和限制采集过程中的样品移动非常重要。此外，尽管由软组织的在线相衬断层扫描提供的对比边缘对DVC是有用的，但相衬成像对其准确性的影响还有待研究。由于同步加速器设备的时间有限，扫描参数通常在成像过程中确定，其对DVC精度的影响尚未完全了解。在这里，我们使用先前发表的椎间盘相衬断层扫描数据来评估i)纤维图像纹理，ii)投影数量，iii)断层重建方法，iv)相衬传播距离对DVC结果的影响。通过可视化目标函数映射，可以更好地了解图像纹理如何影响最佳DVC跟踪，从而识别跟踪不准确性。当减少投影数时，DVC受图像高频噪声的影响最小，但精度有所降低。迭代重建方法提高了图像信噪比，从而显著降低了DVC位移的不确定性。传播距离影响了DVC的精度。在传播距离范围内获得一致的DVC结果，与最小尺度特征形成对比，其中；太短的距离不能提供足够的特征来跟踪，而太长则会导致边缘效应不一致，特别是在较大的变形时。尽管该研究仅限于单一样品类型和图像设置，但该研究为优化纤维结缔组织原位相衬x射线断层扫描的图像质量和扫描时间提供了一般指导。
In-line phase contrast synchrotron tomography combined with in situ mechanical loading enables the characterisation of soft tissue micromechanics via digital volume correlation (DVC) within whole organs. Optimising scan time is important for reducing radiation dose from multiple scans and to limit sample movement during acquisition. Also, although contrasted edges provided by in-line phase contrast tomography of soft tissues are useful for DVC, the effect of phase contrast imaging on its accuracy has yet to be investigated. Due to limited time at synchrotron facilities, scan parameters are often decided during imaging and their effect on DVC accuracy is not fully understood. Here, we used previously published data of intervertebral disc phase contrast tomography to evaluate the influence of i) fibrous image texture, ii) number of projections, iii) tomographic reconstruction method, and iv) phase contrast propagation distance on DVC results. A greater under-standing of how image texture influences optimal DVC tracking was obtained by visualising objective function mapping, enabling tracking inaccuracies to be identified. When reducing the number of projections, DVC was minimally affected by image high frequency noise but with a compromise in accuracy. Iterative reconstruction methods improved image signal-to-noise and consequently significantly lowered DVC displacement uncertainty. Propagation distance was shown to affect DVC accuracy. Consistent DVC results were achieved within a propagation distance range which provided contrast to the smallest scale features, where; too short a distance provided insufficient features to track, whereas too long led to edge effect inconsistencies, particularly at greater deformations. Although limited to a single sample type and image setup, this study provides general guidelines for future investigations when optimising image quality and scan times for in situ phase contrast x-ray tomography of fibrous connective tissues.