OCTREE-BASED MODELING OF COMPUTED-TOMOGRAPHY IMAGES

Manipulation of computed tomography image data at the scanner console to produce slices of the body at arbitrary positions in currently either fairly slow or else very expensive to achieve in real-time. The paper presents a modelling techniuqe based on octrees which builds a three-dimensional model from the scanned slices and then allows the production of arbitrarily sliced images and projections, volume calculations, etc. The Millar polyhedron is introduced as a new technique used to build the octree. It exploits the volume coherence in the image data in such a way that the octree nodes can be directly specified from its output. It is clearly demonstrated that the transputer approach can allow the production of a real-time system at lower cost. Experimental results indicate that the algorithms are inherently concurrent and are suited to implementation in a parallel processing environment such as that provided by the transputer. They also indicate the degree of data compression obtained by using the technique, compared with direct storage of the raw data.