MAXILLARY ALVEOLAR BONE IMAGING - WIENER FILTER DESIGN

Optimal digital filter design is essential for noise suppression in th e detection of subtle radiographic bony changes. The purpose of this s tudy was to determine the signal (Ps) and noise (Pn) power spectra of sampled maxillary alveolar bone, to derive the optimal Wiener filter t ransfer function, H, from sets of Ps and Pn, and to quantify noise sup pression through application of this filter. Sixteen standardized radi ographs were made of five interproximal bony areas, each area from a s eparate dry human maxilla. The radiographs were digitized (0.02 mm/pix el resolution) and identical profiles (scan lines) generated between l ead markers for each set of films. Ps was calculated from the averaged scan line of each set, Pn was calculated from the difference between the noisy images and the averaged scan line for each set, and an avera ge maxillary H was calculated from the sets of Ps and Pn. Filtering of the 80 noisy sample radiographic profiles with H resulted in a 39% re duction in noise. Application of this digital filter should significan tly improve detection of radiographic bony changes in the maxilla.