Digitized video subject positioning and surveillance system for PET

Head motion is a significant contribution to the degradation of image quality of positron emission tomography (PET) studies. Images from different studies must also be realigned digitally to be correlated when the subject position has changed. These constraints could be eliminated if the subject´s head position could be monitored accurately. The authors have developed a video camera-based surveillance system to monitor the head position and motion of subjects undergoing PET studies. The system consists of two CCD (charge-coupled device) cameras placed orthogonally such that both fact and profile views of the subject´s head are displayed side by side on an RGB video monitor. Digitized images overlay the live images in contrasting colours on the monitor. Such a system can be used to: (1) position the subject in the field of view (FOV) by displaying the position of the scanner´s slices on the monitor along with the current subject position; (2) monitor head motion and alert the operator of any motion during the study; and (3) reposition the subject accurately for subsequent studies by displaying the previous position along with the current position in a contrasting colour