Precise determination of soil structure parameters in a X-ray and γ-ray CT combination methodology

Abstract

Linear and mass attenuation coefficients from the X-ray and gamma ray in transmission Computed Tomography – CT are measured and evaluated by a dual energy ratio. By X-ray CT interaction the Hounsfield attenuation ratio is calculated for the main soil components in simulated samples. An experimental set up with different soil components to make up the soil phantom was prepared for scanning in both CT modalities. This procedure provides a simulation of soil sampling in particulate media whose density is close to the natural soil density. Discrete energy in a single beam gamma ray CT allows a precise comparison with mass attenuation coefficient from reference NIST XCOM database values. In an X-Ray CT model XT H 225 from Nikon Metrology, the soil phantom was evaluated in continuous spectrum for mass attenuation coefficient measurements. A detailed soil structure analysis was carried out by means of imaging processing following X-ray transmission interaction with the soil phantom. Measurements of the soil particulate media density and radiometric attenuation coefficients found a 1.5% maximal error when compared to NIST XCOM database values. The results suggest that combining gamma and X rays CT makes feasible a precise methodology for soil structure investigation, and therefore, it allows producing sharper, more informative images, a process that can be availed for new materials technology.