Touching tooth segmentation from CT image sequences using coupled level set method

We focus on the technique to construct and visualize the individual tooth model from CT image sequences for dental diagnosis and treatment. One challenging problem for dental CT images is that tooth crown regions are touching with other teeth in some slices. The common boundary for two adjacent teeth is missing. We propose a coupled variational level set method with region competition of two adjacent teeth to generate the virtual common boundary for them. Moreover the tooth region presents un-uniform intensity level and leads to the suspicious inner edges. We use the normal direction of the evolving contour and the gradient direction of the image to determine true or false outer boundaries and remove the suspicious inner edges. Finally we use the similar tooth shape feature from the CT image sequences to segment out all the tooth contours in different slices starting from the specified initial slice and initial contours. Both segmentation result in 2D images and visualization of each individual tooth model in 3D space verify our method.