Non-Invasive PET Head-Motion Correction via Optical 3D Pose Tracking

We have developed a method for motion correction in PET-CT brain scanning that relies on optical pose tracking of natural facial features and multi-interval image reconstruction. No fixtures or markers are affixed to the subject. A compact stereo camera is mounted within the bore of a Siemens Biograph mCT PET-CT scanner. Images are acquired at 6-30/sec. Scanner acquisition start and stop times are recorded to achieve synchronization between the scanner list file and image pose sequence. Face detection is used to locate head regions for 3D measurement. Pose tracking is performed to an initial reference image. The pose data, in the form of a 4-dimensional rotation-translation matrix, are analyzed to identify quiescent intervals in which the pose x, y, and z translations vary less than 0.5 mm rms and the pose Euler angles vary less than 0.01 rms. Reconstruction is accomplished by dividing the scan into a sequence of sinograms with acceptable motion and incorporating the pose information iteratively in the reconstruction. Manikin studies with attached point sources demonstrate that repositioning is achieved with rms uncertainty <; 0.5 mm. Human subject studies demonstrate repositioning to ~ 1.0 mm rms.