An automatic recognition of the frontal sinus in x-ray images of skull.

In the present paper, a procedure is developed for fully automatic recognition of the frontal sinus in cranial radiographs. An X-ray image of a whole skull is required at the input of the procedure, which consists of three subsequent steps: the selection of a rectangular region of interest, containing the sinus; detection of the line of brow ridges; and fronto-nasal suture, detection of the borders of the frontal sinus. The recognition algorithm is based on a method of connectivity-preserving thresholding, introduced in the present study, and on watersheds from markers. Totally, 50 X-ray images have been analyzed. The frontal sinus borders were recognized correctly in 41 cases.