An automatic method of synthesizing panoramic radiograph by unwrapping dental CT image

Panoramic radiographs synthesized from dental CT images manifest high quality than conventional dental panoramic radiograph and have been used in clinical treatment, but some manual operations are needed in current synthesizing algorithms. This paper presents a new algorithm to synthesize panoramic radiographs from dental CT images automatically. Firstly, projection image of the horizontal CT image is generated by maximum intensity projection (MIP). Then, a modified Ostu´s threshold method is used to segment dental arch area in the projection images. After that, a reference curve is obtained by fitting the medial axis of dental arch area. Finally, the CT slices are unwrapped normal to the reference curve and the panoramic radiograph is generated by synthesizing the projection of unwrapped images in frontal axis. This algorithm is fully automatic and the panoramic radiograph synthesized from dental CT images with this algorithm shows less geometric distortion and blurring.