Spectral K-edge subtraction (SKES) is an imaging technique that takes advantage of the sharp rise in the mass attenuation coefficient of specific elements within an object at their K-edge to produce separate and quantifiable distributions of each element. In this paper, a high-sensitivity and wide bandwidth SKES imaging system for computed tomography applications on biological samples is presented. X-ray images are acquired using a wide and continuous energy spectrum that encompasses the absorption edges of the target materials. System characterization shows that high energy resolution (approximately 3 × 10−3) and unprecedented large energy bandwidth (around 15%) are achieved over a field-of-view of several centimeters. Imaging results obtained on contrast elements relevant for biomedical applications, namely silver, iodine, xenon, and barium, demonstrate the system sensitivity to concentrations down to 0.5 mg ml−1. The achievement of a large energy bandwidth allowed the simultaneous imaging of the K-edges of iodine, xenon, and barium and provided an accurate concentration estimation and distinction of co-localized contrast elements, leading the way for future simultaneous cardiovascular (iodine), pulmonary (xenon), and gastrointestinal/inflammatory (barium) imaging applications.
