Effective atomic number and electron density determination using spectral x-ray CT

摘要

We present Spectral X-ray Computed Tomography (SCT) estimations of material properties directly from energydependentmeasurements of linear attenuation coefficients (LAC). X-ray Computed Tomography (CT) is commonlyutilized to characterize the internal properties of an object of interest. Dual-Energy X-ray CT allowsmaterial characterization into energy-independent physical properties such as Z_e and electron density ρ_e. However,it is not robust in presence of dense materials and metal artifacts. We report on the performance of amethod for system-independent characterization of materials that introduces a spectroscopic detector into X-rayCT, called spectral ρ_e/Ze estimation (SRZE). We benchmark the SRZE method against energy-integrated measurementsin material classification tests, finding superior accuracy in the predictions. The advantage of thistechnique, over other methods for material characterization using x-ray CT, is that it does not require a set ofreference materials for calibration. Moreover, the simultaneous detection of spectral features makes it robust tohighly attenuating materials, since the energy intervals for which the attenuation is photon limited can easily bedetected and excluded from the feature estimation.