Soil matrix study using a hybrid a-Se/CMOS pixel detector for CT scanning

Computed tomography (CT) is a non-invasive means of localizing a region of interest within an object, which enables the investigation of soil distributions and localized flow processes within soil pore systems. CT scanning allows for cross-sectional successions that provide visibility within the environment of plant samples. Knowledge of the characteristics of the soil pore system is essential for evaluating various processes that take place between root-soil interactions. In this study, we investigate the potential application of a high-resolution amorphous selenium (a-Se) direct conversion detector on complementary metal-oxide-semiconductor (CMOS) readouts for micro-CT scanning of a soil matrix to image the status of aggregation and networks of pore spaces within intact soil. The combination of the intrinsic high spatial resolution of a-Se and small pixel CMOS readouts provide detailed visualization in the soil aggregates of the plant samples. The x-ray energy and plant soil thickness were varied during the investigation for imaging the root-soil. A 10 μm spatial resolution and noise limited performance of eight photons/pixel at 20 keV were achieved. High attenuation of x-rays in thick soil poses challenges however fine details are observable in thinner samples and care should be taken when choosing soil thickness and container material.