Helical and axial cone beam filtered backprojection (CB-FBP) reconstruction algorithms using a general window function

A window function is derived for cone beam reconstruction using filtered backprojection (CB-FBP) algorithms under both helical and circular source trajectories. The window function can be conceived as a generalization of the well-known Tam-window function that is originally derived for cone beam reconstruction under helical source trajectory. Rather than defining the window boundaries in a detector, the general window function deals with data redundancy by selecting the rays with the smallest cone angle. The primary benefit of the proposed general window function is the capability of appropriately dealing with data redundancy and removing cone beam artifacts under not only helical but also circular source trajectories. Based on the so-called cone-parallel geometry, a computer simulation study has been conducted to evaluate the general window function under both helical and circular source trajectories.