Cone-Beam Computed Tomography Dataset of a Walnut

Summary This dataset is a collection of X-ray projection images of a walnut imaged in a cone-beam computed tomography (CBCT) scanner. The dataset also includes a metadata file, specifying the scan geometry and other important scan parameters. Description Sample Information The sample is a walnut in its shell. For the scanning process double-sided tape was used to attach the sample to a plastic tube placed into the rotation stage. Scanner The measurements were acquired using a cone-beam computed tomography scanner designed and constructed in-house in the Industrial Mathematics Computed Tomography Laboratory at the University of Helsinki. The scanner consists of a molybdenum target X-ray tube (Oxford Instruments XTF5011), a motorized rotation stage (Thorlabs CR1-Z7), and a 12-bit, 2240x2368 pixel, energy-integrating flat panel detector (Hamatsu Photonics C7942CA-22). Scan Settings 721 X-ray projections were acquired using an angle increment of 0.5 degrees. The X-ray source voltage and tube current were set at 40 kV and 1 mA, respectively. The exposure time of the flat panel detector was set to 1000 ms. Data Post-Processing Two correction images were acquired before scanning the sample. A dark current image was created by averaging 100 images taken with the X-ray source off. A flat-field image was created by averaging 100 images taken with the X-ray source switched on with no sample placed in the scanner. After the scan, dark current and flat-field corrections were applied to each projection image using the Hamamatsu HiPic imaging software version 9.3. Data Format The X-ray projections are stored in .tif format. The metadata is contained in .txt file with formatting that is both human-readable and machine-readable. Notes Due to a slightly misaligned center of rotation in the scanner, the CT reconstructions can appear blurry. It was empirically observed that this problem can be compensated for quite well by shifting each projection left by 5 pixels, using circular boundary conditions, before performing any other operations on the projections. Research Group This dataset was produced by the Inverse Problems research group at the Department of Mathematics and Statistics at the University of Helsinki, Finland: https://www2.helsinki.fi/en/researchgroups/inverse-problems. Additional Links This dataset was originally created as part of a tutorial on working with measured X-ray data in computed tomography. A video tutorial on the measurement process can be found on the Inverse Problems Channel on YouTube at https://www.youtube.com/watch?v=CWUomAmUDys. To get started with the data, we recommend looking at the HelTomo toolbox, specifically created for working with CBCT data collected in the Industrial Mathematics Computed Tomography Laboratory, and available at https://github.com/Diagonalizable/HelTomo. Please note that this is a an entirely separate dataset from the Walnut dataset accessible at https://zenodo.org/record/1254206, although both datasets have been created by the same research group. Contact Details For more information or guidance in using these datasets, please contact alexander.meaney [at] helsinki.fi.

数据集概述
本数据集为一批经锥束计算机断层扫描（cone-beam computed tomography, CBCT）扫描仪成像的核桃X射线投影图像集。本数据集同时包含一份元数据文件，用于标注扫描几何结构及其他关键扫描参数。

数据集描述
样本信息
本次扫描的样本为带壳核桃。扫描过程中，使用双面胶将样本固定于安装在旋转台上的塑料管中。

扫描设备
本次测量使用由赫尔辛基大学工业数学计算机断层扫描实验室自主设计搭建的锥束计算机断层扫描系统完成。该系统由钼靶X射线管（Oxford Instruments XTF5011）、电动旋转台（Thorlabs CR1-Z7）以及一款12位、分辨率2240×2368像素的能量积分式平板探测器（Hamamatsu Photonics C7942CA-22）组成。

扫描参数
本次扫描共采集721幅X射线投影图像，角度步长为0.5度。X射线源管电压与管电流分别设置为40 kV与1 mA，平板探测器的曝光时长设为1000 ms。

数据后处理
扫描样本前，需采集两幅校正图像：通过采集100次X射线源关闭状态下的图像并取平均，得到暗电流图像；通过采集100次无样本放置、X射线源开启状态下的图像并取平均，得到平场图像。扫描完成后，使用滨松HiPic成像软件（版本9.3）对每幅投影图像执行暗电流校正与平场校正。

数据格式
X射线投影图像以.tif格式存储，元数据存储于.txt格式文件中，其格式兼具人类可读性与机器可读性。

注意事项
由于扫描仪的旋转中心存在轻微偏移，CT重建结果可能出现模糊现象。经实验验证，在对投影图像执行其他操作前，通过循环边界条件将每幅投影左移5像素，可较好地补偿该问题。

研究团队
本数据集由芬兰赫尔辛基大学数学与统计系逆问题研究团队制作：https://www2.helsinki.fi/en/researchgroups/inverse-problems。

附加链接
本数据集最初是作为计算机断层扫描实测X射线数据处理教程的一部分创建的。有关扫描过程的视频教程可在YouTube的逆问题频道（Inverse Problems Channel）中查看，链接为：https://www.youtube.com/watch?v=CWUomAmUDys。
如需上手处理该数据集，我们推荐使用专为工业数学计算机断层扫描实验室采集的CBCT数据开发的HelTomo工具箱，其开源地址为：https://github.com/Diagonalizable/HelTomo。
请注意，本数据集与Zenodo平台上编号为1254206的核桃数据集并非同一数据集，尽管二者均由同一研究团队制作。

联系方式
如需获取更多信息或使用该数据集的相关指导，请联系alexander.meaney [at] helsinki.fi。

搜集汇总

背景与挑战

背景概述

该数据集是一个核桃的锥束计算机断层扫描（CBCT）数据集，包含721张X射线投影图像（.tif格式）和描述扫描几何与参数的元数据文件。数据由赫尔辛基大学逆问题研究组使用自建扫描仪采集，扫描设置包括40 kV电压、1 mA管电流和0.5度角度增量，并经过暗电流和平场校正，适用于计算机断层扫描算法开发和教育教程。