Camera-Guided Coordinate System Alignment for Neuromagnetic Source Estimation

Coordinate system alignment is usually performed by localizing a set of coils attached to the subject’s head in both the coordinate systems of the head and a whole-head neuromagnetometer device. This conventional approach may cause instability of neuronal source localization when the estimated coil positions are not stable or when the coils are not tightly attached. This paper presents a new coordinate system alignment technique without using coils. Instead, the proposed method utilizes a calibrated camera to monitor feature points attached to the subject’s face. Coordinate system alignment is then achieved by determining the head pose in neuromagnetometer device coordinate system. According to the phantom experiments, we demonstrate the feasibility, stability, and accuracy of the proposed camera-guided alignment method.