Feasibility Study of an Improved Single-Energy Material Decomposition Method for Computed Tomography

Computed tomography (CT) scan that uses two distinct X-ray spectra in measurement allows for a dual-energy material decomposition (DEMD). DEMD performs decomposition of the two basis materials used in various imaging applications to improve clinical diagnosis, but it requires specialized CT scanners. Recently, single-energy material decomposition (SEMD) based on X-ray path-length estimation yielded the same results as DEMD when the signal errors are nonexistent in the measurements from the objects composed of only two materials. In SEMD, the decomposition is performed using pregenerated look-up tables containing material-specific values as a function of the measurements and X-ray path lengths. The use of these tables, however, is time-consuming, and the results may not be accurate when measurements are degraded by electronic noise and photon starvation. In this study, we propose an improved SEMD method to provide more accurate material decomposition using conventional CT scanners. The proposed SEMD performs the decomposition based on the physical model of X-ray imaging with the use of measurements and estimated path lengths. Material-specific CT images are reconstructed using a filtered-back-projection algorithm. The performance of the proposed method is evaluated on both simulated data and experimental measurements. This method in practical CT scans yielded material decomposition results similar to that elicited by DEMD. Thus, it can be a viable option to provide material-specific information for clinical diagnosis using conventional CT scanners.