Multielectrode cochlear implantation is the most effective treatment for pr
ofound sensorineural hearing loss. In vivo three-dimensional 3-D localizati
on of cochlear implant electrodes is important for modeling of the electric
al field in the cochlea, design of electrode arrays, and may improve speech
processor programming for better speech recognition. The prerequisite for
3-D localization of the electrodes is their 2-D localization in x-ray radio
graphs. In this paper, we develop a practical method to localize the electr
odes with high efficiency, accuracy, and reproducibility. In this method, a
priori knowledge of the electrodes and their approximate positions are uti
lized, an intelligent thresholding and segmentation mechanism is embedded,
and the electrode center is computed as the weighted geometric center of se
gmented electrode pixels. Experiments with physical phantoms and human data
demonstrate the feasibility and utility of this method. The PC-based progr
am developed for this project is disseminated on the Web, (C) 2000 American
Association of Physicists in Medicine.