Reduction Of Metal Artefacts In Cbct Caused By Needles Crossing The Fov Border

Cone beam CT reconstructions are an accurate and efficient intra-procedural method for assessing the positioning of biopsy or ablation needles inside the human body. Commonly encountered issues are metal artefacts produced by the needle that is crossing the border of the field of view (FOV). We combine two approaches for metal artefact reduction (MAR) by exchanging information between the two methods. The first method performs a second pass reconstruction after segmenting the metal inside the FOV volume and subtracting the metal shadow from the sinogram. The second method focuses on the sinogram data to suppress objects outside the reconstruction FOV. Superior performance of this combined method is demonstrated on simulated and clinical data.