IBCN   20355
INSTITUTO DE BIOLOGIA CELULAR Y NEUROCIENCIA "PROFESOR EDUARDO DE ROBERTIS"
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
A low-cost and robust photogrammetry method for determining electrode positions
Autor/es:
VON ELLENRIEDER NICOLÁS; BELTRACHINI LEANDRO; BLENKMANN ALEJANDRO; FERNANDEZ CORAZZA MARIANO; KOCHEN SILVIA; MURAVCHIK CARLOS
Lugar:
Montreal
Reunión:
Congreso; Congreso; 30th International Epilepsy Congress; 2013; 2013
Institución organizadora:
ILAE/IBE
Resumen:
Purpose: The position of the electroencephalography electrodes should be taken into account to perform high quality EEG source localization. We describe a photogrammetry method for determining these positions with nothing but a camera. No special requirements are needed for the images, so the method does not take more than a minute of the patient′s time, and the pictures can be taken without moving the patient to a dedicated zone. Method: Based on images taken from different and arbitrary angles, we solve a nonlinear problem to reconstruct the 3D position of the electrodes. The algorithm inputs are the 2D positions of the electrodes on the pictures and it solves a large nonlinear problem iteratively to estimate the electrode and camera positions, taking into account the projective geometry of the images. Results: The method was tested with different subjects, cameras, and operators. The results were very repeatable in terms of the dispersion of the electrode positions among different reconstructions. The mean dispersion value was 0.7 mm, and in 95% of the cases the dispersion was below 1.6 mm. The same experiments with an electromagnetic positioning pencil, with an additional sensor devoted to head tracking, yielded a higher dispersion with a mean value of 1.7 mm and a 95% percentile of 3.3 mm. Conclusion: The proposed method is completely non-invasive, portable, fast for the patient, and low cost, since a simple cellphone camera is sufficient to achieve the reported results. Software to aid in the labeling of the electrodes in the pictures is under development.