3D Analytic Cone-Beam Reconstruction for Multiaxial CT Acquisitions

Abstract EN

A conventional 3rd generation Computed Tomography (CT) system with a single circular source trajectory is limited in terms of longitudinal scan coverage since extending the scan coverage beyond 40 mm results in significant cone-beam artifacts.

A multiaxial CT acquisition is achieved by combining multiple sequential 3rd generation axial scans or by performing a single axial multisource CT scan with multiple longitudinally offset sources.

Data from multiple axial scans or multiple sources provide complementary information.

For full-scan acquisitions, we present a window-based 3D analytic cone-beam reconstruction algorithm by tessellating data from neighboring axial datasets.

We also show that multi-axial CT acquisition can extend the axial scan coverage while minimizing cone-beam artifacts.

For half-scan acquisitions, one cannot take advantage of conjugate rays.

We propose a cone-angle dependent weighting approach to combine multi-axial half-scan data.

We compute the relative contribution from each axial dataset to each voxel based on the X-ray beam collimation, the respective cone-angles, and the spacing between the axial scans.

We present numerical experiments to demonstrate that the proposed techniques successfully reduce cone-beam artifacts at very large volumetric coverage.