Аннотация:This work describes the synthesis, analysis, and testing of the novel type of La/graphene composites as potential contrastingagents (CAs) for photon-counting computed tomography (PCCT). The impregnation of oxidized graphene nanoflakes (GNFs)with Lanthanum nitrate solution resulted in uniform distribution of La-containing particles on the flake surface with particle sizeof about 2–3 nm. La was confirmed to be a suitable contrasting element for PCCT that could be visualized in reference phantommedia and in the presence of other CAs. Minimum concentration of La in the composites determined by PCCT was in the rangeof 2.5–5 mg·ml−1.