  Background: Dual-energy (DE) imaging techniques in cone-beam computed
tomography (CBCT) have potential clinical applications, including material
quantification and improved tissue visualization. However, the performance of
DE CBCT is limited by the effects of scattered radiation, which restricts its
use to small object imaging. Purpose: This study investigates the feasibility
of DE CBCT material decomposition by reducing scatter with a 2D anti-scatter
grid and a measurement-based scatter correction method. Methods: A 2D
anti-scatter grid prototype was utilized with a residual scatter correction
method in a linac-mounted CBCT system to investigate the effects of robust
scatter suppression in DE CBCT. Scans were acquired at 90 and 140 kVp using
phantoms that mimic head, thorax, and abdomen/pelvis anatomies. The effect of a
2D anti-scatter grid with and without residual scatter correction on iodine
concentration quantification and contrast visualization in VME images was
evaluated. Results: In CBCT images, a 2D grid with or without scatter
correction can differentiate iodine and water after DE processing in human
torso-sized phantom images. However, iodine quantification errors were up to 10
mg/ml in pelvis phantoms when only the 2D grid was used. Adding scatter
correction to 2D-grid CBCT reduced iodine quantification errors below 1.5 mg/ml
in pelvis phantoms, comparable to iodine quantification errors in multidetector
CT. Conclusions: This study indicates that accurate DE decomposition is
potentially feasible in DE CBCT of the human torso if robust scatter
suppression is achieved with 2D anti-scatter grids and residual scatter
correction. This approach can potentially enable better contrast visualization
and tissue and contrast agent quantification in various CBCT applications.
