Application of X-ray CT to liquid security inspection: System analysis and beam hardening correction

The motivation of X-ray CT application to liquid security inspection (LSI) is to identify and classify liquids filled in bottles without bottles being opened. In this paper, the system design of an LSI scanner is analyzed and a beam hardening (BH) correction method is presented. In our method, a Full-liquid linearization is used and the lookup table (LUT) technique is introduced to quickly implement this procedure. Lack of prior knowledge, we present a blind BH correction approach. We store some representative liquid models in advance. Raw polychromatic projection is first corrected (using the Full-liquid correction) by a default model (water). Basing on the reconstruction results, a new model will be carefully selected to do this again, unless the scanned liquid matches our correction model.