3D Surface Realignment Tracking for Medical Imaging: A Phantom Study with PET Motion Correction

We present a complete system for motion correction in high resolution brain positron emission tomography (PET) imaging. It is based on a compact structured light scanner mounted above the patient tunnel of the Siemens High Resolution Research Tomograph PET brain scanner. The structured light system is equipped with a near infrared diode and uses phase-shift interferometry to compute 3D representations of the forehead of the patient. These 3D point clouds are progressively aligned to a reference surface and thereby giving the head pose changes. The estimated pose changes are used to reposition a sequence of recon- structed PET frames. To align the structured light system with the PET coordinate system a novel registration algorithm based on the PET trans- mission scan and an initial surface has been developed. The performance of the complete setup has been evaluated using a custom made phantom based on a plastic mannequin head equipped with two positron emitting line sources. Two experiments were performed. The rst simulates rapid and short head movements, while the second simulates slow and contin- uous movements. In both cases, the system was able to produce PET scans with focus the PET reconstructions. The system is near ready for clinical testing.