Introducing the THz time domain CT system for evaluating kernel weight and plumpness of sunflower seed

Abstract

The Terahertz (THz) time domain computed tomography (CT) system was used for evaluating kernel weight and plumpness of sunflower seed in present study. Specifically, a series of THz projections of the sunflower seed on a rotation stage were captured by a customized transmission mode THz time domain imaging system from different angles. These projections were preprocessed and then modelled by the inverse Radon transform to reconstruct the three-dimensional (3D) sunflower seed. The shapes and structures of sunflower seeds in reconstructed volumetric images were well presented. The volume ratio (obtained by THz CT imaging) and the area ratio (obtained by RGB imaging) of the whole seed to the kernel were calculated as 3D and 2D plumpness, respectively. The comparison between these two different plumpness indicating that our 3D plumpness can better describe the sunflower seed structure. Correlation coefficient (R) between sum intensity values of kernel voxels and kernel weights is 0.89 at 1.2 THz. This is the first application of applying THz CT systems to agri-food research, and the results indicate that THz time domain CT can be a useful nondestructive tool for evaluating weight and plumpness of intact sunflower seed. In addition, there is potential to extend the THz time domain CT system to the analysis of other agri-food sample types.