Material Identification Methods in Spectral Radiography Using CdTe Semiconductor Detectors

Material identification in radiography is traditionally performed by dualenergy systems, using double exposure technique or two-layers detectors. Performance of such systems results from the closeness of the materials to be discriminated, from photonic noise, and energetic discriminating power of the detector. For difficult problems such as explosive detection in luggage, conventional dual-energy radiography provides only a crude material characterization. Recently emerged semiconductors based X-ray detectors offer new capabilities in energy discrimination. They provide multi-energy data, which require new methods to be processed. This paper is proposing a new material identification method based on an experimental calibration protocol. The identification process relies on a likelihood maximization among the samples of the calibration database. This study is aiming at evaluating the gain brought by spectroscopic detectors for material discrimination.