A Dual-Energy CBCT With Reduced Scatter and Cone Beam Artifacts Using an X-Ray Source Array and Interlaced Spectral Filters

OBJECTIVE: To design a dual-energy cone beam computed tomography (DE-CBCT) scanner with reduced scatter and cone beam artifacts. METHODS: The scanner designed for maxillofacial imaging comprises a carbon nanotube (CNT) X-ray source array with multiple focal spots ("sources") and an energy integrating flat panel detector (FPD). The X-ray photons from each focal spot were narrowly collimated in the axial direction and were filtered by interlaced low- and high-energy spectral filters. Two sets of projection images were acquired by sequentially activating the X-ray beams from each source in one gantry rotation. The projections were processed using a one-step inversion algorithm. An anthropomorphic head phantom, a Defrise phantom and a water-equivalent phantom containing calcium and iodine inserts were used to compare the performance of the new dual-energy multisource CBCT (DE-MS-CBCT) with a conventional DE-CBCT using the same air-kerma. RESULTS: The DE-MS-CBCT eliminated the cone beam artifacts, reduced the degree of cupping artifacts from 14.53% to 2.94%, and lowered the mean relative error of water density from 15.3% to 1.7%, while the accuracies for iodine and calcium densities were comparable. The contrast-noise-ratios (CNR) of the calcium and iodine inserts against the solid water increased by 4.8% -53.4%. CONCLUSION: The DE-MS-CBCT reduces scatter and cone-beam artifacts, increases the image CNR, and enhances accuracy of materials quantification without increasing X-ray exposure compared to the conventional DE-CBCT. SIGNIFICANCE: The results demonstrate a new DE-CBCT method with improved image quality and accuracy of materials quantification without the need for an energy sensitive detector or kV switching.