Rebinned Filtered Back-Projection Reconstruction From Truncated Data for Half-Covered Helical Cone-Beam Computed Tomography

For applications of imaging large objects by small planar detectors in helical cone-beam computed tomography (CT), the field-of-view (FOV) half-covered scanning technique is a preferred choice as it can almost double the FOV with only about half the cross-section of an object irradiated with x-rays at all projection views. However, the projections are transversely truncated, resulting in truncation errors in reconstructed images if no compensatory measures are taken. In this paper, the half-covered single slice rebinning method is developed, in which images are reconstructed by performing two steps of rebinning followed by a three-dimensional (3D) filtered-backprojection (FBP) -based algorithm. The algorithm rebins the half-covered cone-beam projections into parallel-beam data which covers the whole cross-section of the object, thus resulting in nearly no truncation errors in the reconstructed images. Numerical simulations and experimental results are presented to demonstrate the algorithm and to compare it with existing algorithms. Preliminary results indicate the proposed half-covered single slice rebinning algorithm improves reconstruction quality.