Effect of the number of projections in X-ray CT imaging on image quality and digital volume correlation measurement
Effect of the number of projections in X-ray CT imaging on image quality and digital volume correlation measurement
复制标题
X射线CT成像投影数量对图像质量和数字体积相关测量的影响
DOI：
10.1016/j.measurement.2022.111061
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发表时间：
2022
期刊：
影响因子：
5.6
通讯作者：
Pan Bing
中科院分区：
文献类型：
--
作者：
Zhang Xuanhao;Sun Lijuan;Wang Bo;Pan Bing
数字体积相关（DVC）通过将不同状态下采集的被测物体的体积图像进行相关，量化内部三维位移场和应变场。当使用基于X射线CT的DVC时，投影的数量是影响重建体积图像的采集时间和质量的关键参数，并且因此影响DVC测量的精度和时间分辨率。更多的投影导致用于DVC计算的高质量体积图像，但是较长的采集时间和X射线源的显著热漂移。很少的投影导致更快的采集和更少的热漂移，但可能会降低图像质量，从而引起更大的DVC测量误差。因此，在CT成像过程中选择合适的投影数对DVC测量具有实际意义。为了解决这一难题，在这项工作中，投影的数量对DVC测量与X射线CT的影响进行了实验研究。首先，利用FDK（Feldkamp）算法重建了不同投影数的散斑体图像，分析了投影数对DVC测量的影响。然后，对泡沫铜样品进行了真实的重扫描和压缩实验，以进一步研究投影数对DVC测量的影响。仿真和真实的实验表明，投影越多，成像时间越长，但体积图像和DVC测量质量越高。DVC测量误差随预测值的增加而减小，但下降速率不同。因此，可以根据DVC测量精度和时间分辨率的要求，基于结果指定适当的投影数量。对于本次真实的压缩实验中使用的特定X射线CT设备，建议使用36张60次投影，以平衡测量精度和时间分辨率，为追求更高的精度，需要使用720次以上的投影。
Digital volume correlation (DVC) quantifies internal 3D displacement and strain fields by correlating the volume images of a tested object acquired at different states. When using X-ray CT-based DVC, the number of projections is a key parameter that affects the acquisition time and quality of reconstructed volumetric images, and therefore the precision and temporal resolutions of DVC measurement. More projections result in high-quality volume images for DVC calculation but longer acquisition time and pronounced thermal drifts of the X-ray source. Few projections lead to quicker acquisition and fewer thermal drifts, but may degrade image quality and thus induce larger DVC measurement errors. Selecting an appropriate number of projections during CT imaging is therefore of practical significance for DVC measurement. To solve this dilemma, the effect of the number of projections on DVC measurements with X-ray CT is experimentally investigated in this work. First, numerically simulated speckle volume images with different numbers of projections were reconstructed by using FDK (Feldkamp) algorithm, and the influence of the number of projections on DVC measurement was analyzed. Then, real rescan and compression experiments performed on a copper foam sample were carried out to further study the effect of projection number on DVC measurements. Both simulation and real experiments show that more projections result in longer imaging time but higher quality volume image and DVC measurement. DVC measurement errors decrease with the increase of projections at different decline rates. Therefore, an appropriate number of projections can be specified based on the results according to the requirements of DVC measurement precision and temporal resolution. For the specific X-ray CT device used in this real compression experiment, 36 ∼ 60 projections are suggested to balance measurement precision and temporal resolution, and more than 720 projections are necessary for pursuing higher accuracy.