Using Anti-Aliased Signed Distance Fields for Generating Surgical Guides and Plates from CT Images

We present a method for generating shell-like objects such as surgical guides and plates from segmented computed tomography (CT) images, using signed distance fields and constructive solid geometry (CSG). We develop a userfriendly modeling tool which allows a user to quickly design such models with the help of stereo graphics, six degrees-of-freedom input, and haptic feedback, in our existing software for virtual cranio-maxiollofacial surgery planning, HASP. To improve the accuracy and precision of the modeling, we use an anti-aliased distance transform to compute signed distance field values from fuzzy coverage representations of the bone. The models can be generated within a few minutes, with only a few interaction steps, and are 3D printable. The tool has potential to be used by the surgeons themselves, as an alternative to traditional surgery planning services.