Hyperspectral X-ray CT datasets of an aluminium phantom containing three metal-based powders

<strong>General Data description:</strong> This is a set of two hyperspectral (energy-resolved) X-ray CT projection datasets of a multi-phase phantom. It was acquired in a custom-built, laboratory micro-CT scanner with an energy-sensitive HEXITEC detector in the Henry Moseley X-ray Imaging Facility at The University of Manchester. The following data contains all the files necessary for reconstruction, following two hyperspectral scans of a metal, multi-phase phantom. The phantom consists of an external aluminium cylinder, with three holes, each filled with a different metal-based powder (CeO₂, ZnO, Fe). Each powder provides a unique attenuation signal, with CeO₂ in particular producing a distinct spectral marker which can be measured by an energy-sensitive detector. Two identical scans were acquired, with only the exposure time per projection changed. <strong>File descriptions:</strong> Contained is an image (.jpg) of the sample, along with five MATLAB (.mat) data files, as well as a single text (.txt) file. Where necessary, the files have been named to match the dataset they belong to, based on the different exposure times used for each dataset. Phantom_design_measurements.jpg contains a photograph of the physical phantom, combined with a diagram showing full sample measurements. Powder_phantom_scan_geometry.txt gives a breakdown of the full sample and detector geometry used when acquiring the raw projections for both scans. powder_phantom_30s_sinogram.mat contains the 4D sinogram constructed following flatfield normalisation of the raw projection data, where an exposure time of 30 s was used for each projection. The 4D array contains the total number of energy channels acquired during scanning, followed by vertical and horizontal pixel number, and finally total projections angles acquired during scanning. The total number of channels in the file is 400, however relevant data is stored only up to channel 220, with the remaining channels containing noise and scatter, and therefore can be discarded. No corrections or filters have been applied to the data. powder_phantom_180s_sinogram.mat is the 4D sinogram for the dataset, when exposure times of 180 s were used for each projection, following flatfield normalisation. A discontinuity occurs at projection 137 due to an interruption in the scan procedure. The total number of channels in the file is 400, however relevant data is stored only up to channel 220, with the remaining channels containing noise and scatter, and therefore can be discarded. No corrections or filters have been applied to the data. Energy_axis.mat provides a direct conversion between the energy channels, and the energies (in keV) that they correspond to, following a calibration procedure prior to scanning. This is the same for both datasets. FF_30s.mat contains the 4D flatfield data acquired when no sample was present, in the case of 30 s exposure times. This data was used to normalise the projection datasets, as the sinogram was constructed. The full 400 channels are included. FF_180s.mat contains the 4D flatfield data for the dataset where 180 s exposure times were used. The full 400 channels are included.数据集总体描述：本数据集包含两套多相体模的高光谱（hyperspectral，能量分辨型energy-resolved）X射线CT投影数据。该数据采集自英国曼彻斯特大学亨利·莫斯利X射线成像实验室的定制化实验室微型CT扫描仪，搭载了能量敏感型HEXITEC探测器。以下为该金属多相体模两次高光谱扫描后得到的全部重建所需文件。该体模外部为铝制圆柱结构，内部开设三个孔洞，分别填充三种不同的金属基粉末：二氧化铈（CeO₂）、氧化锌（ZnO）以及铁（Fe）。每种粉末均具备独特的衰减信号特征，其中二氧化铈可产生独特的光谱标记，可通过能量敏感型探测器进行采集。本次共完成两次扫描流程完全一致的扫描，仅调整了单幅投影的曝光时长。 文件说明：本次提供的文件包含一张样品实拍图（.jpg格式）、五个MATLAB数据文件（.mat格式）以及一个文本文件（.txt格式）。所有文件均根据其所属数据集对应的曝光时长进行命名，以区分不同数据集。 Phantom_design_measurements.jpg：该文件为体模实物实拍图与完整样品测量示意图的整合文件。 Powder_phantom_scan_geometry.txt：该文本文件详细说明了两次扫描采集原始投影数据时所采用的样品与探测器几何布局参数。 powder_phantom_30s_sinogram.mat：该文件为采用30秒单投影曝光时长的数据集的4D正弦图数据，由原始投影数据经过平场校正后构建得到。该4D数组的维度依次为扫描采集的总能量通道数、垂直像素数、水平像素数以及总投影角度数。文件中总计包含400个能量通道，但有效数据仅存储至第220通道，剩余通道仅包含噪声与散射信号，可直接丢弃。该数据未经过任何校正或滤波处理。 powder_phantom_180s_sinogram.mat：该文件为采用180秒单投影曝光时长的数据集的4D正弦图数据，由原始投影数据经过平场校正后构建得到。由于扫描过程中出现中断，第137号投影位置存在数据不连续问题。文件中总计包含400个能量通道，但有效数据仅存储至第220通道，剩余通道仅包含噪声与散射信号，可直接丢弃。该数据未经过任何校正或滤波处理。 Energy_axis.mat：该文件提供了扫描前校准得到的能量通道与对应能量（单位：千电子伏特，keV）之间的直接转换关系，两套数据集采用完全相同的校准参数。 FF_30s.mat：该文件为无样品状态下、采用30秒曝光时长采集得到的4D平场数据，用于构建正弦图时对投影数据集进行平场校正，文件包含全部400个能量通道的数据。 FF_180s.mat：该文件为采用180秒曝光时长的数据集对应的4D平场数据，文件包含全部400个能量通道的数据。