Quantifying skull shape

This paper describes a technique for automatically quantifying the shape of the skull cavity seen on an axial slice in a CT brain scan. The development of this algorithm derives from the need to normalise CT scan data according to skull size and shape for the purpose of comparing new patient data with that from past cases. This algorithm uses image processing techniques to find the inner edge of the bones of the skull on an axial slice, so that its shape can be represented by a radius function. A simple measure of shape asymmetry is defined. It is also shown that this can be quantified more precisely by harmonic analysis using the Fourier transform of the radius function. This paper describes the design of the algorithm and its performance on axial slices taken from a database of CT brain scans from 528 patients.