Abstract

Background

In computed tomography (CT) quality assurance, alignment of image quality phantoms is crucial for quantitative and reproducible evaluation and may be improved by alignment correction. Our goal was to develop an alignment correction algorithm to facilitate geological sampling of sediment cores taken from a cold-water coral mount.

Methods

An alignment correction algorithm was developed and tested with a CT acquisition at 120 kVp and 150 mAs of an image quality phantom. Random translation (maximum 15 mm) and rotation (maximum 2.86°) were applied and ground-truth was compared to parameters determined by alignment correction. Furthermore, mean densities were evaluated in four regions of interest (ROIs) placed in the phantom low-contrast section, comparing values before and after correction to ground truth. This process was repeated 1000 times. After validation, alignment correction was applied to CT acquisitions (140 kVp, 570 mAs) of sediment core sections up to 1 m in length, and sagittal reconstructions were calculated for sampling planning.

Results

In the phantom, average absolute differences between applied and detected parameters after alignment correction were 0.01 ± 0.06 mm (mean ± standard deviation) along the x-axis, 0.11 ± 0.08 mm along the y-axis, 0.15 ± 0.07° around the x-axis, and 0.02 ± 0.02° around the y-axis, respectively. For ROI analysis, differences in densities were 63.12 ± 30.57, 31.38 ± 32.10, 18.27 ± 35.57, and 9.59 ± 26.37 HU before alignment correction and 1.22 ± 1.40, 0.76 ± 0.9, 0.45 ± 0.86, and 0.36 ± 0.48 HU after alignment correction, respectively. For sediment core segments, average absolute detected parameters were 3.93 ± 2.89 mm, 7.21 ± 2.37 mm, 0.37 ± 0.33°, and 0.21 ± 0.22°, respectively.

Conclusions

The alignment correction algorithm was successfully evaluated in the phantom and allowed a correct alignment of sediment core segments, thus aiding in sampling planning. Application to other tasks, like image quality analysis, seems possible.

中文翻译：

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自动对准校正算法在地质CT成像中的实验应用：体模研究并将其应用于冷水珊瑚丘的沉积物核中。

摘要

背景

在计算机断层扫描（CT）质量保证中，图像质量体模的对齐对于定量和可重现的评估至关重要，并可通过对齐校正进行改进。我们的目标是开发一种路线校正算法，以促进对从冷水珊瑚山中获取的沉积物芯进行地质采样。

方法

开发了对准校正算法，并通过在120 kVp和150 mAs的图像质量体模上进行CT采集进行了测试。进行随机平移（最大15 mm）和旋转（最大2.86°），并将地面真实性与通过对准校正确定的参数进行比较。此外，在幻影低对比度部分中的四个感兴趣区域（ROI）中评估了平均密度，比较了对地面真实性进行校正前后的值。重复该过程1000次。验证后，将对准校正应用于长度不超过1 m的沉积物岩心断面的CT采集（140 kVp，570 mAs），并计算矢状重建以进行采样计划。

结果

在体模，对准校正后施加和检测到的参数之间的平均绝对差分别为0.01±0.06毫米（平均值±标准偏差）沿X轴，沿着0.11±0.08毫米ý的周围-轴，0.15±0.07° X -轴和分别围绕y轴的0.02±0.02° 。对于ROI分析，对齐校正前的密度差异为63.12±30.57、31.38±32.10、18.27±35.57和9.59±26.37 HU，对齐校正后的密度差异为1.22±1.40、0.76±0.9、0.45±0.86和0.36±0.48 HU，分别。对于沉积物岩心段，平均绝对检测参数分别为3.93±2.89 mm，7.21±2.37 mm，0.37±0.33°和0.21±0.22°。

结论

对准校正算法已在模型中成功评估，并允许沉积物芯段正确对准，从而有助于采样计划。似乎可以应用到其他任务，例如图像质量分析。