Representative Gamma-ray Computed Tomography Calibration for Applications in Soil Physics

Abstract

Tomographic image quality in soil physics ap- plications is extremely dependent on calibration. Here, good calibrations of the system are necessary to avoid errors during soil evaluations by computed tomography (CT), which can hamper interpretations of physical pa- rameters of the soil. In order to analyze the relevance of a good calibration curve (CC) for measurements of soil physical properties, determinations of soil bulk density (ρb ) were obtained using four different CCs established for a homemade CT scanner dedicated especially to soil physics. The calibrations of the system were ob- tained through the relationship between tomographic units and corresponding linear attenuation coefficients (μ1) of different materials. Data show that different calibration curves produce distinct ρb values affecting the quality of results of this soil physical property when evaluated by CT. However, it was demonstrated that even using non-homogeneous materials for CT calibra- tion the results of ρb practically are of the same order of magnitude of the whole system error estimated in 0.05 g cm −3 (taking the water as reference).