Improved Trajectories in C-Arm Computed Tomography for Non-Circular Fields of View

In C-arm computed tomography, the field of view (FOV) is often not sufficient to acquire certain anatomical structures, e.g. a full hip or thorax. Recently proposed methods to extend the FOV use a fixed detector displacement and a 360◦ scan range to double the radius of the FOV. These trajectories are designed for circular FOVs. However, there are cases in which the required FOV is not circular but rather an ellipsoid. In this work, we show that the use of a dynamically adjusting detector offset can reduce the required scan range when using a non-circular FOV. Furthermore, we present an algorithmic approach which determines the minimal required scan ranges for arbitrary FOVs given a certain detector size. Our results indicate a promising reduction of the necessary scan range especially for ellipsoidal objects. Additionally initial reconstruction results of our method yielded comparable results as when using a fixed detector offset with a full 360◦ rotation.