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J Med Imaging (Bellingham). 2015 Oct;2(4):044003. doi: 10.1117/1.JMI.2.4.044003. Epub 2015 Nov 18.

Automatic segmentation of mandible in panoramic x-ray.

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Sharif University of Technology , Department of Computer Engineering, Azadi Ave., Tehran 11155-9517, Iran.
Isfahan University of Medical Sciences , School of Dentistry, Department of Maxillofacial Radiology, Isfahan 81595-158, Iran.


As the panoramic x-ray is the most common extraoral radiography in dentistry, segmentation of its anatomical structures facilitates diagnosis and registration of dental records. This study presents a fast and accurate method for automatic segmentation of mandible in panoramic x-rays. In the proposed four-step algorithm, a superior border is extracted through horizontal integral projections. A modified Canny edge detector accompanied by morphological operators extracts the inferior border of the mandible body. The exterior borders of ramuses are extracted through a contour tracing method based on the average model of mandible. The best-matched template is fetched from the atlas of mandibles to complete the contour of left and right processes. The algorithm was tested on a set of 95 panoramic x-rays. Evaluating the results against manual segmentations of three expert dentists showed that the method is robust. It achieved an average performance of [Formula: see text] in Dice similarity, specificity, and sensitivity.


automatic segmentation; mandible; medical image; panoramic x-ray; statistical modeling

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