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

To design a dual-energy cone beam computed tomography (DE-CBCT) scanner with reduced scatter and cone beam artifacts.

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 was 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.

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%.

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.

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.