X‐ray computed tomography (CT) is commonly used in soil science to quantify distributions of pores, water and solids within soil samples. Particularly promising for liquid visualization is dual‐energy scanning of samples with added dopant solutions. The approach uses solutions of heavy elements as a proxy for the soil water and utilizes the abrupt increase of the mass attenuation coefficient of heavy elements when crossing an X‐ray absorption edge, detectable by dual‐energy CT scanning. However, a key step in visualization of the added liquid is image segmentation. In partially saturated soils, the X‐ray CT images consist of voxels with the presence of solid, liquid and gaseous phases in different ratios. These ratios are generally ignored by the traditional image segmentation methods, which separate image voxels into groups with either zero or complete saturation by either prevailing phase. The objective of this study was to develop and test a new physically based segmentation approach that accounts for partial saturation of image voxels by liquids. We combined a theoretical equation for detected photon intensity with the mass conservation equation to compute saturation of image voxels by dopant solution applied to the soil. This approach was tested on soil micro‐columns with potassium iodide (KI) solutions. The proposed approach outperformed the traditional segmentation methods, particularly at low and intermediate water contents. Tests conducted for KI solutions in the concentration ranges from 2 to 20% revealed deterioration of the method accuracy with decreasing dopant concentration in the soil. Based on the results of this study we recommend 10 wt% KI solution for quantifying spatial distribution of liquids in soils using dual‐energy X‐ray microtomography.

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基于X射线计算机断层摄影图像的质量平衡方法可量化土壤中的水分分布

X射线计算机断层扫描（CT）在土壤科学中通常用于量化土壤样品中的孔隙，水和固体的分布。对于液体可视化而言，特别有希望的是添加了掺杂剂溶液的样品的双能扫描。该方法使用重元素的解决方案代替土壤水，并利用重能量的质量衰减系数在穿越X射线吸收边缘时的突然增加（可通过双能CT扫描检测到）。但是，可视化添加液体的关键步骤是图像分割。在部分饱和的土壤中，X射线CT图像由体素组成，存在不同比例的固相，液相和气相。传统的图像分割方法通常会忽略这些比率，可以将图像体素按主要相位将其归为零或完全饱和的组。这项研究的目的是开发和测试一种新的基于物理的分割方法，该方法可以解决液体对图像体素的部分饱和。我们将检测到的光子强度的理论方程与质量守恒方程相结合，以通过应用于土壤的掺杂剂溶液来计算图像体素的饱和度。该方法已在含碘化钾（我们将检测到的光子强度的理论方程与质量守恒方程相结合，以通过应用于土壤的掺杂剂溶液来计算图像体素的饱和度。该方法已在含碘化钾（我们将检测到的光子强度的理论方程式与质量守恒方程式相结合，以通过应用于土壤的掺杂剂溶液来计算图像体素的饱和度。该方法已在含碘化钾（KI）解决方案。所提出的方法优于传统的分割方法，尤其是在中低含水量的情况下。对浓度在2％到20％范围内的KI溶液进行的测试表明，随着土壤中掺杂剂浓度的降低，方法的准确性下降。根据这项研究的结果，我们建议使用10重量％KI溶液通过双能X射线显微断层摄影术定量分析土壤中液体的空间分布。