Cone-Beam Computed Tomography Dataset of a Chicken Bone Imaged at 4 Different Dose Levels

Summary This dataset is a collection of X-ray projection images of a chicken leg bone imaged in a cone-beam computed tomography (CBCT) scanner, using four different dose levels. The dataset also includes a metadata file for each of the scans, specifying the scan geometry and other important scan parameters. Description Sample Information The sample is a chicken bone obtained from a cooked chicken. The bone was boiled to remove soft tissues, after which it was left to dry in room temperature for several months to remove extra moisture. For the scan the sample was placed directly into the rotation stage and secured with a screw. 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 The dataset consists of four different scans of the same sample. For each scan 721 X-ray projections were acquired using an angle increment of 0.5 degrees. The X-ray source was set at 40 kV with a 0.5 mm aluminum filter. For the different scans, the relative doses, tube currents, and exposure times were: 100 % relative dose: tube current 1 mA, exposure time 2000 ms, 50 % relative dose: tube current 1 mA, exposure time 1000 ms, 25 % relative dose: tube current 0.5 mA, exposure time 1000 ms, 10 % relative dose: tube current 0.2 mA, exposure time 1000 ms. The scans were made in sequence, proceeding from the lowest dose to the highest dose. Data Post-Processing Before the scans, two correction images were acquired for each scan setting. 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 are contained in .txt files 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 4 pixels, using circular boundary conditions, before performing any other operations on the projections. It was also observed that the scans are not entirely aligned, with a small angular discrepancy between each reconstruction. 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 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. Contact Details For more information or guidance in using these datasets, please contact alexander.meaney [at] helsinki.fi.数据集概述 本数据集为一组鸡腿骨的锥束计算机断层扫描（CBCT）投影图像，采用四种不同剂量等级采集。数据集还包含每份扫描的元数据文件，用于说明扫描几何结构及其他重要扫描参数。 数据集描述 样本信息 本次扫描的样本为取自熟食鸡腿的骨骼。先将骨骼煮沸以去除软组织，随后在室温下放置数月以去除多余水分。扫描时将样本直接放置于旋转载物台，并用螺丝固定。 扫描设备 数据采集使用芬兰赫尔辛基大学工业数学计算机断层扫描实验室自主研发搭建的锥束计算机断层扫描系统。该系统包含钼靶X射线管（Oxford Instruments XTF5011）、电动旋转载物台（Thorlabs CR1-Z7），以及一款12位分辨率、2240×2368像素的能量积分型平板探测器（Hamamatsu Photonics C7942CA-22）。 扫描设置 本数据集包含同一样本的四组不同扫描。每组扫描均以0.5°的角度增量采集721张X射线投影图像。X射线源管电压设置为40 kV，搭配0.5 mm厚的铝滤片。四组扫描的相对剂量、管电流及曝光时间参数如下： 100%相对剂量：管电流1 mA，曝光时间2000 ms； 50%相对剂量：管电流1 mA，曝光时间1000 ms； 25%相对剂量：管电流0.5 mA，曝光时间1000 ms； 10%相对剂量：管电流0.2 mA，曝光时间1000 ms。 扫描顺序为从低剂量到高剂量依次进行。 数据后处理 每组扫描前，均针对该扫描设置采集两张校正图像：暗场图像通过采集X射线源关闭状态下的100张图像取平均得到；平场图像通过采集无样本放置、X射线源开启状态下的100张图像取平均得到。扫描完成后，使用Hamamatsu HiPic 9.3版成像软件对每张投影图像进行暗场与平场校正。 数据格式 X射线投影图像以.tif格式存储。元数据存储于.txt文件中，其格式兼具人类可读性与机器可解析性。 注意事项 由于扫描系统的旋转中心存在轻微偏移，CT重建图像可能出现模糊现象。经实验验证，在对投影图像进行其他操作前，通过循环边界条件将每张投影图像左移4个像素，可较好地补偿该问题。此外还发现，各扫描间未完全对齐，不同重建结果间存在微小角度偏差。 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小组制作，相关页面地址：https://www2.helsinki.fi/en/researchgroups/inverse-problems。 补充资料 若要快速上手该数据集，推荐使用专为工业数学计算机断层扫描实验室采集的锥束CT数据开发的HelTomo工具箱，其开源仓库地址为https://github.com/Diagonalizable/HelTomo。 联系方式 如需获取更多信息或该数据集的使用指导，请联系[e-mail]。