Abstract：
:Automatic identification of landmarks in cephalometry is very important and useful for orthognathic surgery. A computerised automatic cephalometric analysis system (CACAS), based on image processing, is presented. For an original X-ray image, median filtering and histogram equalisation are used to improve image quality. The edge of an X-ray image is detected by a wavelet transform and Canny filter. Seventeen landmarks in cephalometry are successfully identified by knowledge-based edge tracing and changeable templates. Seventy-three measurements based on distances, angles and ratios between landmarks are computed automatically. The reliability of the landmarks and the validity of the measurements are compared for automatic and manual operation. The values of measurements obtained by CACAS are more precise and reliable: the mean error for linear measurements is less than 0.9mm; the mean error for angular measurements is less than 1.2 degrees. The rate of validity is over 80%, even if the image quality is poor. For an image with a high signal-to-noise ratio, the rate of validity of landmarking and measurements using the CACAS system is over 90%.
journal_name
Med Biol Eng Computjournal_title
Medical & biological engineering & computingauthors
Yang J,Ling X,Lu Y,Wei M,Ding Gdoi
10.1007/BF02345280keywords:
subject
Has Abstractpub_date
2001-05-01 00:00:00pages
279-84issue
3eissn
0140-0118issn
1741-0444journal_volume
39pub_type
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