High energy tomography using cadmium zinc telluride detectors

Cadmium zinc telluride (Cd0.8Zn0.2Te) is nowadays one of the most promising room temperature semiconductors for X- and γ-ray detection. Indeed, its physical characteristics make this detector very suitable for operating under high-intensity fluxes, such as those produced by linear accelerators. For this reason, CdZnTe has been chosen for the set-up of a tomographic facility based on 12-MeV linear accelerator. This system is a first generation tomograph; it has already been used for preliminary phantoms image acquisition, showing rather good imaging capabilities. The polychromaticity of the source may induce severe beam-hardening artifacts in the final tomographic images. Extensive experimental studies have been carried out to optimize correction algorithms able to reduce such artifacts. A set of images of relevant samples have been acquired in order to evaluate the relationship between the absorption coefficients and the resulting CT numbers.