  This paper presents an innovative automatic fusion imaging system that
combines 3D CT/MR images with real-time ultrasound (US) acquisition. The system
eliminates the need for external physical markers and complex training, making
image fusion feasible for physicians with different experience levels. The
integrated system involves a portable 3D camera for patient-specific surface
acquisition, an electromagnetic tracking system, and US components. The fusion
algorithm comprises two main parts: skin segmentation and rigid
co-registration, both integrated into the US machine. The co-registration
software aligns the surface extracted from CT/MR images with patient-specific
coordinates, facilitating rapid and effective fusion. Experimental testing in
different settings validates the system's accuracy, computational efficiency,
noise robustness, and operator independence. The co-registration error remains
under the acceptable range of~$1$ cm.
