|
Dual-energy CBCT acquires projection images using two different x-ray spectra, enabling material quantification and synthesis of virtual monoenergetic images to reduce metal artifacts. Current methods for dual-energy CBCT imaging include using either a fast kVp switching x-ray source or a dual-layer detector. In this work, we demonstrate a novel approach to dual-energy CBCT by spectral filtration of an x-ray source that contains two focal spots. The method generates two distinct x-ray spectra and independently programmable dose and dose rate for the two energies, without a significant cost increase over a conventional CBCT. Two spectral filters were attached to the x-ray exit windows of a dual-focus carbon nanotube x-ray source operating at a constant tube voltage. As the source and detector rotate around the object, alternating high and low energy projections were acquired by alternatively activating electron emission from the two cathodes. A one-step material decomposition based on separable quadratic surrogate functions was implemented. A water equivalent plastic phantom with calcium and iodine contrast inserts was imaged to evaluate the accuracy of material decomposition. Results demonstrate a functional low-cost dual-energy CBCT system by spectral filtration, with the accuracy for material quantification comparable to those from the dual-layer detector and fast kVp switching based DE-CBCT.
|
